Construction 3D-printing in reducing the incidence of long latency respiratory diseases among construction workers in the UK

Onsite construction workers are exposed to many hazards which affect their body. However, dust and silica dust inhalation are often overlooked, most likely because it takes years to identify the side effects. The damage inflicted to the lungs is often irreversible as it is often discovered when it is too late. The aim of this research is to address the problem of occupational respiratory diseases among construction workers and investigate the potential of construction 3D printing in reducing the incidence of some of these diseases. The research objectives were to: identify the causes of the most prevalent respiratory diseases in construction; investigate the strategies of minimising onsite dust/ silica dust exposure; investigate the benefits of 3D printing in the minimisation of onsite dust/ silica dust exposure; explore the barriers of 3D printing in the minimisation of onsite dust/ silica dust exposure and explore the strategies for wider adoption of construction 3D printing to minimise the incidence of long latency respiratory diseases among construction workers. To achieve these objectives, a literature review was conducted, an online survey was carried out and professionals and researchers in the 3D printing field were interviewed to obtain relevant information to understand the intricacies of the new technology and its impact from workers’ health perspectives.


Background
The construction industry is labour-intensive and is considered one of the most dangerous industries due to its high rate of injury, fatality and long latency health issues (Filho et al. 2021). In 2020, 1.7 million workers were reported to suffer from work-related ill health in the United Kingdom (UK) (HSE 2021a), with 17 000 estimated new cases of lung problems caused or made worse by work each year (HSE 2021a). A study carried out by the HSE (2021b) based on 2019/2020 data concluded that approximately 12 000 lung disease deaths in the UK were linked to past exposures at work and over 500 construction workers are believed to die from lung cancer caused by silica dust alone (Institution of Occupational Safety and Health 2014). Automatic systems and robotic machinery are believed to become necessary in improving health and safety in construction (Knights et al. 2015), by reducing the risks of falls, injuries from lifting heavy objects, providing a more controlled work environment and creating distance between workers and the hazards. Such an example can be construction three-dimensional (3D) printing, a relatively new technology, which is considered to have great potential in the industry (Shahrubudin et al. 2019). The literature contains a number of studies on 3D printing as a construction method, on materials and technologies used in the construction practice, but its impact on the health and safety field should be analysed further. Ning et al. (2021) stressed the importance to conduct studies on the health and safety implications of construction 3D printing, because of the impact it can have on promoting the wider use and because it is a vast unchartered territory. Although there are studies about the harmful effects of the particles resulting from using desk 3D printers and the materials they use for extrusion such as acrylonitrile butadiene styrene (ABS), or polylactic acid (PLA) (Dobrzyńska et al. 2022), the benefits of automatic construction systems including 3D printing far outweigh their harmful effects (Sinka et al. 2022).

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The aim of this research is to address the problem of occupational respiratory diseases among construction workers, investigate the implementations of 3D printing in the construction industry and its potential implications in decreasing the incidence of some of these diseases.
The specific research objectives are to investigate the: causes of the most prevalent respiratory diseases in construction, strategies of minimising onsite dust/ silica dust exposure, benefits of 3D printing in the minimisation of onsite dust/ silica dust exposure, barriers of 3D printing in the minimisation of onsite dust/silica dust exposure and strategies for wider adoption of construction 3D printing to minimise the incidence of long latency respiratory disease among construction workers.

Health and safety in construction practice
According to a study published in 2021, the construction industry played a crucial role in the economic recovery of the UK post Covid-19 pandemic (Balmforth et al. 2021). It contributes to the wellbeing of the members of society, both through their home and work environment. From the employment perspective, the industry is creating additional jobs every year, in construction and related-disciplines such as: architecture, engineering, quantity surveying, manufacturing and plant hiring (Chartered Institute of Building 2020a). Construction provides approximately 7% of the jobs in the UK and three quarters of the country's capital assets, worth over £3.6 billion (Chartered Institute of Building 2020a). However, the industry suffers from a number of health and safety related challenges. Professional health and safety is an important challenge not just for the construction industry but at a global level. In 2016, 1.9 million people died in the world because of work-related diseases and injuries (World Health Organization and International Labour Organization 2021). In construction, it represents a major concern because of the nature of the work itself, which by definition, is a dangerous activity. In 2020-2021 period, the average level for health and safety fine increased to £145,000 and almost £27 million in fines were issued in the UK construction industry (Health and Safety Executive 2021a). Keeping on top of health and safety procedures places a big burden on 30% of the SMEs who took part in a study carried out in 2018 (Health and Safety Executive 2018), although the costs with fines and the fees for intervention are estimated to be over £60 000 more of a burden than the costs of compliance (Mirkowski 2021). Another challenge faced when implementing health and safety procedures is the lack of industry culture to see health and safety as a benefit for the overall business activity. Seventy four percent of SMEs in the 2018 study agreed that a number of health and safety measures they take is to protect themselves from being held liable for any accident (HSE 2018).
The Health and Safety at Work Act 1974 was enacted in order to secure health, safety and welfare of employees at work, those who may be affected by their work, control the use of explosive and highly flammable substances and control the emission into the atmosphere of dangerous substances. The Construction (Design and Management) Regulations 2015, which aim to improve the health and safety in the industry, refer to the Health and Safety at Work Act but focuses more on following the health and safety procedures and ensuring the paperwork is copacetic. The purpose of health and safety, as described by Health & Safety Executive, is to prevent employees from getting hurt at work or ill through work. The Institution of Occupational Safety and Health defines health and safety in the workplace as a process to manage risks to protect the workers and the business (Institution of Occupational Safety and Health 2021). Occupational health and safety is defined as the science of anticipation, recognition, evaluation and control of hazards arising in or from the workplace that could impair the health and well-being of workers, taking into account the possible impact on the surrounding communities and the general environment (Alli 2008).
According to Kiersma (2014), occupational safety focuses mainly on preventing injuries to personnel resulted from activity in the workplace. Heath, on the other hand, is a different concept. The difference between the two concepts is emphasised by Struthers (Struthers 2016) and consists in the speed of outcome and speed of corrective action. An accident has an immediate effect, it is visible and the people who witness it can take immediate actions to try to correct it. On the other hand, occupational health hazards have a delayed or chronic effect on the workers, and give visible signs only years later (Struthers 2016) through diseases of disorders. The Occupational Safety and Health Administration differentiate between the two concepts, when they categorise the most common hazards in a workplace by separating them into safety related (tripping, unguarded machinery) and five other health related categories: biological (exposure to bacteria and viruses), physical (dust, radiation), ergonomic (vibration, repeating movements), chemical (fumes, pesticides) and work organisation hazards (workload, workplace violence).
In the recent years, the attention moved to the concept of occupational health, and it is now known and accepted that the workplace can make employees ill or have a negative impact on pre-existing health problems. The World Health Organisation defines health as a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity (WHO 1948). Following the same principle, Professor Stephen Holgate, at the University of Southampton gave a definition for health as being 'more than the absence of illness and more about living and engaging fully' (De Selincourt 2018). Health is one of the fundamental rights of every human being (WHO 1948).

Categories of hazards and occupational diseases
The Occupational Safety and Health Administration define six categories of occupational hazards (Occupational Safety and Health Administration n.d.) as follows: safety, biological, physical, ergonomic, chemical and work organisation hazards. Occupational safety deals with the first category of hazards and occupational health covers the remaining five. The International Labour Organization categorises the occupational diseases by target organ systems, listed as follows (International Labour Organization 2010): Respiratory system diseases -caused by exposure to dusts and harmful substances (Tavakol et al. 2017). Some examples are lung cancer (caused by asbestos), silicosis (caused by silica dust from concrete, mortar or sandstone), chronic obstructing pulmonary disease (COPD) (caused by inhalation of various types of dust) (Stocks et al. 2011). According to the Institution of Occupational Safety and Health, approximately half of million people are being exposed to silica dust at work in the UK and approximately five million in the European Union (AirBench 2023). A study conducted by Health & Safety Executive concluded that chronic obstructive pulmonary disease (COPD) resulting from past workplace exposures is the cause of approximately 4 000 deaths annually, with construction workers being a significant risk group (HSE 2021d).
Musculoskeletal disorders -this is a consequence of manual labour (Timofeevaa et al. 2017)-caused by vibration from the machinery used on construction sites, heavy items handling, repetitive movements, extreme posture of the wrist, prolonged pressure on elbows and knees. According to Health & Safety Executive, 470 000 workers in the UK suffer from work related musculoskeletal disorders, based on 2020/21 data (HSE 2021d).
Skin disease -allergic contact dermatitis or even cancer caused by repetitive exposure to cement products, paints and other chemicals. The Health & Safety Executive concluded that in 2019, there were almost 900 new cases of workrelated dermatitis (HSE 2021e).
Hear loss -caused by constant exposure to noisy works and equipment. Based on the Labour Force Survey data gathered from 2019 until 2022, HSE concluded that there were an estimated 11 000 prevalent cases of hearing problems each year caused or made worse by work (HSE 2022a).
Mental and behavioural disorders -caused by limitedterm contracts and job uncertainty, long hours, pressure to complete work on time and within budget, time away from family and the masculine culture within the industry (CIOB 2020b).
The Chartered Institute of Building conducted a survey which revealed that 87% of respondents experienced anxiety, 70% of them experienced depression, 97% experienced stress and 26% had suicidal thoughts (CIOB 2020b). The records show that in 2019, there were approximately 3 400 self-reported work-related illness per 100 000 workers in the UK (Statista 2019). Construction workers can be exposed to a significant number of health hazards throughout their career and can be considered a high-risk category of workers. Although they might have knowledge of the numerous health hazards being exposed to, they do not have a broad view of the situation, nor do they have an understanding of the ramifications and complexity of the matter. A study carried out by the Health & Safety Executive (HSE 2021c) concluded that approximately 12 000 lung disease deaths in the UK were estimated to be linked to past exposures at work. A study on construction dust carried out by Institution of Occupational Safety and Health demonstrated that awareness on this subject among construction workers is reduced (IOSH 2014). Forty two percent of the respondents do not understand the significance of the problem and how it can affect them and 14% are not aware it is a health problem at all (IOSH 2014). The impact of occupational ill-health is twofold: on the worker and on the business. On one hand it creates suffering for the workers and reduces the quality of their life and on the other hand, is responsible for tens of millions of disability adjusted life years globally (WHO and ILO 2021), and has a significant negative impact on the productivity of a business. The study carried out by Gibb, Drake and Jones in collaboration with the Institution of Civil Engineers (Gibb et al. 2018), shows that in 2018, occupational ill-health was estimated to cost the construction employers £848 million each year. This excludes the three times more than the employer's costs incurred by the employees and does not reflect the true costs the employees who suffer from long latency diseases have to cover, as these costs will be incurred towards the end of the work life or after retirement, as concluded in the same study.

Most prevalent respiratory system diseases in construction and their causes
Asbestos is considered the biggest occupational hazard for workers in the construction practice. It is a material used in the past for its insulation properties and it is responsible for over 5000 of deaths per year (HSE 2022c). Prolonged and heavy exposure to asbestos can cause mesothelioma (cancer of the lining of the lungs), lung cancer, asbestosis (scarring of the lung) (HSE 2021d). The danger and seriousness of asbestos impact on health is far more significant than that of dust exposure, be it silica dust or any other type of dust.
Silica dust, found in stone, sand, clay, concrete or mortar (Stocks et al. 2011) is considered the second most dangerous material after asbestos (HSE 2022b). It can cause silicosis, a type of pulmonary fibrosis, when the lung tissue becomes scarred and ultimately impairs the lung's function. The construction industry is well known for creating large amounts of dust generated by concrete or demolition works, cutting grooves, cutting bricks, etc. Given the dynamic nature of a construction site and the changing works every day, protecting workers from dust can be challenging (Mølgaard et al. 2013). Prolonged exposure to dust onsite can cause, among others, COPD and asthma (Stocks et al. 2011). Both diseases bring breathing difficulties, which become worse in time. Given the side effects of the exposure to the causal agent become noticeable only many years after the first exposure, these diseases are classified as long latency (Carder et al. 2017). Demolition operatives are the most affected by dust exposure (Mølgaard et al. 2013), followed by cement workers, concrete and batching workers, cleaning crew (Tavakol et al. 2017), brick masons, plasterers, construction workers cutting concrete or grooves or doing soft demolition (Institution of Occupational Safety and Health 2014).

Health and safety incidences
The International Labour Organisation (ILO) estimated that the construction sector in industrialised countries employs up to 10% of the workforce but accounts for up to 40% of work-related deaths (Lingard 2013). The most recent figures for the UK included in the Report prepared by HSE based on 2020/2021 data, show that 1.7 million working people suffered from a work-related illness, 142 workers were killed at work and over 2300 workers died of mesothelioma due to past asbestos exposures (HSE 2021e). While younger workers might be more exposed to accidents due to lack of experience, older workers prove to be more stubborn when it comes to complying with health and safety policies. Lack of knowledge was identified as a major challenge in minimizing the impact of hazards on site (Hilti and Travis Perkins 2019). Due to the lack of compliance with the regulations, control, procedures and discipline encountered in small businesses, a significant number of health and safety issues are registered in this category of businesses (Timofeevaa et al. 2017). In the UK fines and imprisonment sentences have been introduced in 2016 through the revised Sentencing Guidelines for Health & Safety and Corporate Manslaughter offence and vary based on the company's turnover, level of risk and culpability (AIG Construction Industry Group n.d.). Although the number of prosecution cases brought in the UK by Health & Safety Executive and -in Scotland by the Crown Office and Procurator Fiscal Service (COPFS) and the total amount of fines decreased significantly since 2019, the average level of fine has risen 35% from £107,000 to £145,000 (Health and Safety Executive 2021a). Since the introduction of the revised Sentencing Guidelines in 2016, the construction industry in the UK was hit by heavy financial penalties for health and safety failings. The literature has less examples for fines given to companies for failing the health of employees. An explanation might be the fact that unless the factor has an immediate effect, the ill health is not perceived soon enough. Another explanation is the inability of the ill workers and doctors to track the disease back to a specific employer. For the situation when the factor is a wellknown cause for ill health, a relevant example is the case of Ensure Asbestos Management who failed to protect their employees from asbestos exposure on a project in Plymouth. The director and the contracts manager were sentenced to 10 and 15 years in prison, respectively (HSE 2022c). Despite legislation and regulations in place the number of people involved in various occupational incidents and ill health is still high and most of the causes are preventable.

3D-Printing for minimising health and safety on constructions sites
A survey carried out by the Institution of Occupational Safety and Health (2014) revealed that the most common strategies for controlling dust/silica dust onsite are respiratory protective equipment, local exhaust ventilation (LEV), water suppression and on-tool extraction. Water spray systems are being widely used by demolition contractors on the UK market (Taylor 2016).
A recent poll conducted by Hilti UK (the British branch of a Liechtensteiner multinational company which develops and manufactures products for construction) in collaboration with Travis Perkins (British supplier in construction) showed that the professionals in the construction industry expect that the biggest impact on health and safety will be brought by technology and product innovation (Hilti 2019). This includes the use of drones, network of smart sensors, data monitoring through wearable devices, health and safety training using apps and virtual reality, and the increased use of automation and robotics to reduce the risk workers are exposed to on site (Agarwal et al. 2016). Robots, large scale 3D printers and drones are expected to replace some construction activities such as handling materials, cutting, bricklaying or quality control in areas with limited access (Cousins 2019).
According to Schuldt et al. (2021) construction 3D printing is a construction method, also known as additive manufacturing, which consists in joining material layerupon-layer. Resembling the Fused Deposition Modelling 3D printers, it works based on extrusion technology, it follows a 3D model created with specific software, which is then translated into a programming language understandable to the printer called G-code (Dávila et al. 2022). Once the printer is calibrated, the G-code gives instructions to the printer which pumps concrete through a nozzle and deposits material in layers with specified thickness according to the 3D model (Pacewicz et al. 2018). Figure 1 illustrates the construction 3D printing process.
3D printing technology is called stereolithography and was patented in 1986 by Chuck Hull (Pacewicz et al. 2018). The materials used can be cementitious such as concrete, which is most used, or cement-based mortar, gypsum-based mortar together with aggregates, cement and additives such as ground granulated blast-furnace slag, fly ash, silica fume, and rock powders (limestone and quartz powders), which modify the properties of the material (Pacewicz et al. 2018) and metals (Sati et al. 2021). New materials such as wood based and eco-friendly materials (Kidwell 2017) are being developed. Investment in research for improved materials could have the potential to revolutionise the construction industry. There are a number of technologies used in 3D printing (Pessoa et al. 2021) such as Binder jetting (the materials used are powdered), Directed energy deposition (used with metal powder and wire feedstock); Material extrusion (used with thermoplastic filaments and flowable slurries; Material jetting (used with materials such as waxes); Powder bed fusion (powdered materials are used); Sheet lamination (paper, polymer, metal sheets); Vat photopolymerization (used with materials such as polymer resins). For cementitious materials, five different methods are commonly used: Contour Crafting, Concrete printing, D-Shape, Fused Deposition Modelling (FDM), and Fused material powder (Sati et al. 2021). According to Pessoa et al. (2021) Contour Crafting is the most frequently used method for 3D printing in the Architecture, Engineering and Construction industry (Ghaffar et al. 2018).
Existing literature on 3D printing in construction focuses on technologies used, materials and impact on the labour market if it were to be adopted on a larger scale, but the information on the impact on health and safety of the workers is scarce. The number of projects completed with this technology is small and further studies are required to have an understanding of the implications. From a safety perspective, although workers can be exposed to electrical energy hazards, irradiation hazards, entrapment, thermal hazards (Nozar et al. 2019), this method of construction is done in a controlled environment, safer and more regulated than a construction site which is dynamic, with people working in close proximity and unaware of the risks other colleagues might bring. A 3D printing factory can be set up next to the site (Castenson 2021). From a health perspective, workers can be exposed to powder inhalation and contact in the preparation stage, i.e., pre-manufacturing (Nozar et al. 2019) and even gas inhalation in metal 3D printing. Again, having a 3D printing factory close to site, special equipment can be installed to mitigate the hazards such as: personal protective equipment with respirator, efficient sealing from other areas, monitoring systems for dust and oxygen levels, air filtration and dust extraction unit, wet vacuum cleaner (Nozar et al. 2019) ensuring contaminants can be extracted at source. The manufacturing stage brings a reduced number of hazards to workers, as the work is done by the printer following the coded programme. 3D printing components for construction implies they are measured with utmost accuracy and therefore little or no cutting will be required. Cutting materials such as concrete is a major source of dust, fumes and vapours, all significant hazards for workers' health. Another application which might have a positive impact on worker's health is 3D printing components for modular construction, on a similar principle as CyBe Construction (a technology company for the construction industry) 3D printed house in Milan. If a building can be dismantled and reused, then the process will involve little demolition works, which reduces significantly the dust workers are exposed to. It can then be moved and reassembled in a different location which involves again little hazardous work for the workers.

Positive and negative impacts of 3D printing in construction on health and safety
The literature identified a number of positive impacts of construction 3D printing on health and safety, including the perspective of dust exposure. Firstly, because of its automated nature, it reduces worker's contact with the dust sources (Ryu et al. 2020). From a Covid-19 perspective the use of 3D printing reduces the number of operatives on site and enables social distancing. The use of construction 3D printing can create the conditions for a controlled environment which can be located either on site or in close proximity. It can help create safer work conditions for workers (Hossain et al. 2020). 3D printing can reduce danger for human workers in harsh environments. The automation of the construction process can reduce workloads and prevent fatigue and accidents (Olsson et al. 2021). Another advantage was emphasised by Schuldt et al. (2021) and it is about the fact that the construction method can avoid cutting concrete -a major source of dust onsite-since 3D printed components for construction are measured accurately. Additionally, it can avoid cutting grooves -another important source of dust onsite-because 3D printed walls allow for spaces for pipes and electrical wiring by creating openings or interruptions in deposition when printing walls (Garcia-Alvarado et al. 2021). Cousins (2019) emphasised another positive impact in the form of modular construction using 3D printed components. A modular building, that reached the end of use period in one location, can be dismantled and reused in a different location, instead of going through a demolition process, which is considered the main source of dust onsite (Mølgaard et al. 2013). The use of 3D printing reduces waste which needs to be removed from a construction site (Tay et al. 2020) because of the precision of the design and the code it follows to build structures. This method uses only the quantity of material needed for each specific structure. In order to counteract the risks 3D printing technology poses, a hybrid system that consists of a 3D printing factory and a safety equipment should be set up. This strategy can help workers benefit from the advantages of 3D printing as it can mitigates risks associated with the technology (Salet and Wolfs 2016).
The literature identified several negative impacts of construction 3D printing on health and safety, including the perspective of dust exposure. Firstly, some methods such as D-shape printers use a powder deposition process, cured using a binder (Sati et al. 2021), which can expose the workers to powder inhalation. For other methods involving paste mixtures, the material is based on mixing various types of powder form ingredients and will have to be prepared in a controlled environment. The 3D printing technology is mostly being used on new projects and not on existing projects. Therefore, it can be considered a construction method that can benefit mostly new projects, overlooking the demolition or renovation operatives who are among the categories of workers most affected by dust exposure (Mølgaard et al. 2013). In corelation with the preceding point and based on the present technological progress, 3D printing in construction cannot benefit operatives involved in large projects, unless the method is used for small components of a large-scale structure. The current technology is limited to smaller scale projects (Olsson et al. 2021). Another weak point of 3D printing from a health perspective is the fact that the applications are limited. They do not include surface finishes-the construction stage which is responsible for generating large quantities of dust (Garcia-Alvarado et al. 2021). Additionally, the technology is too expensive and might be considered financially unfeasible for some clients (Austin-Morgan 2022). Another challenge of the new technology is the unknown effects on health of the new materials being used in printing artefacts, what harmful substances can be emitted and how they affect human health (Nagvenker 2021). There is an imperative need for a comprehensive risk assessment to understand the hazards and establish the strategies to mitigate the risks. Finally, the technology might evolve faster than the safety regulations (Olsson et al. 2021) resulting in dangerous circumstances where construction failures lead to injury and loss of life. Time and extensive research are required to understand the weak points of all new technologies and regulations need to take into consideration the results of the research and adapt permanently to new findings.

Strategies of promoting the uptake of 3D printing in construction to reduce exposure to dust
A number of potential factors which can promote the uptake of 3D printing were identified in the literature. One of them can be the work of architects. They can be direct enablers of 3D printing in construction through their design (Olsson et al. 2021). A lifecycle analysis of the impact of 3D printing from all perspectives -cost, health and safety, environment, will have to be carried out once a significant number of projects have been completed using the technology. The information on benefits and also negative impact will have to be disseminated. This will enable construction professionals to make bold, but educated or informed decisions about their applications in architecture, engineering and construction practice. Better developed legislation for this new technology (Olsson et al. 2021) can provide the safer environment it needs to mature and can aid in its adoption. The need to improve sustainability can also promote the adoption of 3D printing in construction. It is argued that additive construction minimises waste resulted from the construction process (Achillas et al. 2015), and some materials use recycled materials, such as glass, instead of aggregate in the concrete mix (Ghaffar et al. 2022).

Research methods
A mixed method consisting of quantitative and qualitative techniques have been adopted for this study with the aim to collect information and gain insight about the domain of interest. Also, using both methods overcomes weaknesses inherent in each method (Hafsa 2019). In order to properly and effectively design and implement the mixed method, a literature review (secondary data) was undertaken. For secondary data collection, literature on health and safety in the construction practice and on construction 3D printing was reviewed. The literature review provides the context for the second part of the study which consists of collecting primary data. For primary data collection, two approaches were used: the questionnaire survey approach and the interviews approach. The survey questionnaire was formed of closed-ended questions. To allow triangulation, the interview questions reflected the ones included in the questionnaire but were left open-ended for participants to elaborate on their views. Both methods complement each other, because one approach gives multiple choice options, and the other encourages participants to contribute freely, following a structured set of questions.
The questionnaire was posted on fifteen relevant health and safety, 3D printing, and construction related groups on the LinkedIn platform. It was also distributed via email to professionals working in the construction industry -contacted directly on the LinkedIn platform. The questionnaire survey generated 67 responses in total. Five survey responses were disregarded as the participants had no knowledge of either respiratory disease in construction or construction 3D printing, leaving 62 relevant responses in total.
Selection of interview participants was determined by their appropriateness and ability to provide substantive answers to the inquiries. The LinkedIn platform facilitated the contact with 110 professionals with experience either in health and safety in construction practice or construction 3D printing. Out of the 110, 33 agreed and participated in the study via email interview. Out of the 33 participants, 18 completed the interview and provided responses to all the questions. The analysis discussed in Sect. "Analysis of results" is based on the 62 responses from the quantitative questionnaire respondents and 18 interview respondents.

Analysis of results
The data resulted from the questionnaire survey was exported into an Excel spreadsheet. The responses were chronologically ordered and the frequency for key factors was determined. The data was presented using charts and analysed.
Content analysis method was used to examine the data collected from the interviews because it comes with both qualitative and quantitative methodology (Krippendorff 2019). From a qualitative content analysis perspective, data is presented in code words and themes, allowing the researcher to go deep with the interpretation of the results (Bengtsson 2016). The data resulted from the interview was checked and structured in order to identify recurring ideas, followed by the identification of codes for representing key themes. For each interview question, the transcripts were read and the main ideas were highlighted. The highlighted excerpts were transferred into an Excel spreadsheet, code were generated and included in separate columns. The codes were then structured into categories and themes. Each theme addressed one of the research objectives as suggested by Bengtsson (2016) and was used to describe what the participants said, by staying close to the text and using excerpts of their responses. Figure 2 presents the framework showing the process for coding and structuring the data and how each research objective is being addressed.
In quantitative content analysis, the frequency of words/ themes associated with each code and facts were expressed as a number or percentage in alignment with Bengtsson (2016). This method was used to analyse the interview data.

Causes of the most prevalent respiratory diseases in construction
In order to identify the causes, the literature was reviewed. This revealed the main causes to be asbestos, silica dust and dust resulted from demolition and construction works. Asbestos is a material present in old buildings and banned in the UK construction industry. For the scope of this study, only the last two, i.e., silica dust and dust will be considered.
Asbestos, a material used in the past for its insulation properties, is considered the biggest occupational hazard for workers in the construction practice which can cause mesothelioma, lung cancer, asbestosis (HSE 2021d). The second most dangerous material after asbestos in the construction industry, is silica dust (HSE 2022a), found in stone, sand, clay, concrete or mortar (Stocks et al. 2011) which can cause silicosis, a type of pulmonary fibrosis. Finally, works such as demolition, cutting grooves, cutting bricks or plastering are well known for creating large amounts of dust. Prolonged exposure to dust onsite can cause, among others, chronic obstructing pulmonary disease and asthma (Stocks et al. 2011). Because the side effects of the exposure to the causal agent become obvious only many years after the first exposure these diseases are classified as long latency (Carder et al. 2017).

Strategies of minimising onsite dust/ silica dust exposure
Findings from literature review The literature review revealed the most common strategies to be spraying water (Shi et al. 2023), respiratory protective equipment (RPE) such as masks and filters, dust removal system (such as dry vacuums and local exhaust ventilation) (Hilti 2019). Dustfree fixing through fastening rather than drilling and wearable detection technology which monitors dust exposure are relatively new strategies (Hilti 2019). Using water and RPE can be considered traditional and affordable measures set in place to control dust exposure. The problem arises when the workers do not use the protective measures provide by the employer due to various reasons such as lack of comfort, training or supervision.
Findings from questionnaire In order to identify the strategies for minimising dust and silica dust exposure, a question about the different strategies was included in the questionnaire. Based on the responses for the questionnaire, it revealed that 95% of the participants and 87% respectively, place their trust into respiratory protective equipment and dust removal systems, such as vacuums, which they consider either quite important or very important. The percentage decreases when asked about spraying water (71% of the respondents) and dust-free fixing through fastening rather than drilling (68% of the respondents). The findings from the online questionnaire survey regarding the strategies to minimise onsite dust/silica dust exposure by the number of respondents who considered them very important and quite important are summarised in Fig. 3.

Categories Codes
Exhaust

Onsite workers
Who are those most likely to be affected by exposure to onsite dust/ silica dust?

Categories Codes
Legislation Legislation Architects and other consultants Government coercion Sustainability pressure 3D printing process Fully automated process Improved materials Affordability Awareness raising Incentives Benefits assessment Assess undergoing projects 3D printing machine People External pressure What strategy will promote a wider adoption of 3D printing in construction to reduce exposure to dust/silica dust?

Fig. 2 Codewords, categories and themes generated
The findings from the online questionnaire survey regarding 3D printing as a measure to minimise onsite dust/silica dust exposure are summarised in Fig. 4.
In line with the limited information found in the literature review, a high number of respondents representing almost 30% were unsure about the potential of construction 3D printing, which can be understandable given the novelty of the technology and the scarce information on the subject. On a positive note, 62% of the respondents considered this new technology very important or quite important in minimising onsite dust/silica dust exposure. This might be explained by the fact that the participants were made aware of this option through the survey, and it created a reflective thought process.

Findings from interviews
The feedback from the interviews revealed the following as main strategies: spraying water, RPE, exhaust ventilation, wet grinding, closed mixer, 3D printing, prefabrication, administrative controls and periodic medical testing. This is summarised in Fig. 5.
With regards to the interview, a question was formulated to capture the measures in managing onsite dust and silica dust. In line with the literature review and the questionnaire survey findings, the interview findings showed that the most important measure in managing the problem of dust onsite is represented by RPE mentioned by 12 of the 18 interviewees, followed by dust removal systems indicated by 8 of the 18 interview participants. 3D printing is appeared in the third position being mentioned by 7 interviewees.
Although the traditional water spraying seems to be an important practice still, with over 70% of the questionnaire survey participants considering it either quite important or very important, the structured interview revealed that only 3 interviewees considered it an important measure in controlling onsite dust exposure. One of the reasons could be Importance of using 3D printing in managing onsite dust/silica dust exposure because it might not be a common practice on 3D printing construction sites. On the other hand, literature shows that water spraying systems are widely used by demolition contractors in the UK (Taylor 2016). 3D printing construction technology is situated in the top three measures indicated by the interview participants, being referenced by almost 40% (7) of the interview participants.

Those with high potential of being affected by onsite dust
Findings from the literature Literature emphasised that everyone on and around a construction site can be affected by dust, no matter their role in the project. As resulted from the literature review, the main categories affected by dust are demolition operatives (Mølgaard et al. 2013), construction workers, brick masons (Tavakol et al. 2017) and plasterers (Institution of Occupational Safety and Health 2014). Painters, site managers and project managers are the least at risk in terms of dust exposure, mainly because they are not present on site all the time and are not close to the dust sources. Inhaling a large quantity of dust every day over many years causes injuries to the lungs, despite their very complex built-in defence mechanisms. The problem does not arise from the fact that the lungs are not equipped to deal with dust, but from their inability to filter and eliminate so many particles over an extended period of time. The problem is created by the work conditions.

Findings from questionnaire
The questionnaire survey findings revealed similar results matching the literature, emphasising that demolition operatives and construction workers are the two categories with the highest risk of exposure to dust. As shown in Fig. 6, according to the online questionnaire survey, 71% of the participants consider that demolition operatives are most likely to be affected by dust/ silica dust exposure, and 61% for the construction workers respectively.

Findings from interviews
In line with the literature review and the survey findings, the interview findings show that the category with a high risk is represented by construction workers which were mentioned by 72% of the respondents. Six interviewees raised a very good point when emphasising that neighbours, both onsite (other operatives not directly involved in the construction works) and offsite can be affected by the large quantities of dust spread in the environment.
"On-site, of course, the workers, because they're on site all day, and other than that, the community around the project site is also the most affected party in term of dust exposures" (Interviewee 14).
The demolition workers have not been referenced by the interview participants, most likely because they were more focused on construction 3D printing and its impact. Nevertheless, it is widely known demolition works produce immense quantities of dust . This attention on the printing process revealed another important category represented by the technicians who prepare and load the 3D printing materials. They were mentioned by 7 of the 18 interview participants. As shown in Fig. 7 printer cleaning operatives and the printer operators can also be exposed to dust, but the risk is considered much lower, as highlighted by Interviewee 11. Technicians prepare the materials needed to produce the concrete for the 3D printer and load them into the mixers. In order to avoid moving the problem of dust exposure form onsite to offsite, attention needs to be paid to protecting the technicians. Some of the solutions highlighted during the interviews were using pre-bagged concrete mix (Interviewee 10) together with RPE for the technicians who mix and load the materials, closed mixers (Interviewee 5) and ultimately a fully automated technology.

Benefits of 3D printing in the minimisation of onsite dust/ silica dust exposure
Findings from the literature In order to identify the benefits, the literature was reviewed. Benefits were identified from various perspectives with focus on how construction 3D printing can help from a health point of view. The literature suggests that a mature 3D printing technology, once it becomes a fully automated process, will reduce the number of operatives needed onsite and it will reduce their contact with the construction process (Hossain et al. 2020). This implies that the contact with the material mixing process will be reduced as well and ultimately can reduce the exposure to dust or silica dust. The project executed by CyBe Construction (first 3D-printed house in the European Union which can be dismantled and reused) prompted the researcher to consider the potential of 3D printed modular buildings in addressing the problem of dust generated from the demolition works. Therefore, the attention is drawn to the controlled environment that this new construction Fig. 6 Categories of onsite operatives with the highest risk of exposure to dust/silica dust -survey results Fig. 7 Categories of onsite operatives exposed to dust/silica dust obtained from structured interviews method can provide, and the fact that it can avoid cutting concrete and grooves since 3D printed walls allow for spaces for pipes and electrical wiring by creating openings or interruptions in deposition when printing walls (Garcia-Alvarado et al. 2021).
Findings from the questionnaire In order to identify the benefits of 3D printing in the minimisation of onsite dust/ silica dust exposure, a question was included in the questionnaire to capture this. The responses for the survey showed that 42% of the participants consider reducing worker's contact with the dust sources and providing a more controlled environment to carry out the works as very important. Similar percentages came back for 5 out of the 6 benefits included in the questionnaire, including the avoidance of cutting concrete and cutting grooves. These align with the findings identified in the literature by Garcia-Alvarado et al. (2021) and Schuldt et al. (2021), but more certainty will be gained once an in-depth exploratory analysis of data from a significant number of completed 3D printed construction projects is carried out.
The idea of using 3D printed components for modular construction and having the option to dismantle the building was received with high scepticism and might have been classified as farfetched, which is completely understandable given the current level of technology. The survey showed that 23% of the survey participants were unsure if the concept of modular buildings with 3D printed components could be included as a benefit of 3D printing in addressing the problem of dust exposure. The findings from the online survey are summarised in Figs. 8 and 9.

Findings from interviews
The feedback from the interviews, summarised in Fig. 10, emphasized reduced contact and reduced number of operatives as main benefits of 3D printing technology in dealing with the problem of dust exposure. These align with the findings from the literature mentioned by 9 and 5 participants respectively, out of 18, an excerpt from one of the interviewees is as follows: Fig. 8 Benefits of construction 3D printing in solving the problem of dust/silica dust exposure -Reduced contact/ Controlled environment -survey results

Fig. 9
Benefits of construction 3D printing in solving the problem of dust/silica dust exposure "I believe 3D printing is a way to minimise the exposure on site, as there is less crew, and direct contact with the material" (Interviewee 12).
Providing a controlled environment, highlighted by Interviewee 4, and the advantage of avoiding cutting and drilling, highlighted by Interviewee 7, were also specified by the participants.
"Some 'printers' can be used in a factory setting to produce prefabricated panels, meaning that where hazardous dust is being generated it can also be extracted and filtered at source to prevent it from spreading and affecting others." (Interviewee 4). "3DCP can definitely minimize the dust exposure of the onsite workers to a minimum. Using a closed system of prefabricated dry material (silos) or custom ready-mix from the local concrete batching plant can minimize the dust levels on site. Also, what can help is that with 3DCP we can prepare many details (mainly openings for cables, tubes, sewage etc.)" (Interviewee 7).
These benefits are strongly connected to the printing process becoming fully automated, as also highlighted by Interviewee 11. "Only automatic loading is safer" (Interviewee 11).
Although the idea of automatic loading was not covered in depth in the benefits section of the interview, it was highlighted in the responses for question 7 when strategies were discussed. The 3D printing process and how it will be carried out will determine the success in addressing the problem of respiratory diseases developed because of dust/ silica dust exposure on construction sites. There is also a significant number of challenges to be overcome before this construction method will be widely used.

Barriers of 3D printing in the minimisation of onsite dust/ silica dust exposure
Findings from the literature In order to identify the barriers of 3D printing in the minimisation of onsite dust/ silica dust exposure, the literature was reviewed.The barriers were discussed from various perspectives with focus on the challenges construction 3D printing can face from a health point of view. The literature suggests that the current state of technology limits the application of 3D printing in construction and does not include certain works such as surface finishes (Garcia-Alvarado et al. 2021) or demolition which generate significant quantities of dust (Mølgaard et al. 2013) in the everyday site activities. An important aspect is that the raw material used comes in powder form and handling and mixing it for the printing stage will generate dust (Sati et al. 2021). This technology comes with another two significant drawbacks which are incipient legislation Sati et al. 2021) and high prices for the equipment. Historically, all new technologies went through these steps which are part of the normal maturing process. This new technology cannot be seen as the absolute solution for the dust exposure problem, as the study suggests it will have to be complemented by additional protective equipment, until it becomes fully automated.
Findings from the questionnaire In order to identify the barriers of 3D printing in the minimisation of onsite dust/ silica dust exposure, a question was included in the questionnaire to capture this. Some of the findings from the questionnaire are indicated in Figs. 11 and 12. The responses for the questionnaire survey showed that 72% of the participants Fig. 10 Benefits of construction 3D printing in solving the problem of dust/silica dust exposure as resulted from the structured interviews consider the fact that construction 3D printing focuses more on new buildings as quite important or very important barrier in addressing the problem of dust exposure. As discussed in the literature review, the most important cause for long latency respiratory diseases is exposure to asbestos.
The survey highlighted that 69% of the participants consider lack of awareness about the negative impact of dust on health to be quite important or very important, matching the findings in the literature which indicates reduced awareness on this subject among construction workers (Institution of Occupational Safety and Health 2014). Additionally, 61% of the participants consider the technology to be too expensive which can explain the level of maturity and the limited projects completed with this technology.

Findings from interviews
The feedback from the interviews, as summarised in Fig. 13, identified the mixing process and the lack of regulations as top two main barriers for 3D printing technology in dealing with the problem of dust exposure.
This information is highlighted in the excerpts from Interviewees 3, 11 and 12, respectively. The results are in line with the findings from the literature and were highlighted by 12 respondents out of 18 and 5 out of 18 respectively. "People still work a lot with dry mixtures especially when the loading of equipment is manual." (Interviewee 11).
"There is lack of legislation on occupational health on 3d construction printing." (Interviewee 3).
"3D printing is facing a wide array of regulatory issues that needs to be resolved before 3D printing is ready for mass adoption." (Interviewee 12).
In line with the literature review, Interviewee 10 highlighted that there are other major sources of dust which cannot be addressed by the use of 3D printing, such as plastering. This might be considered an unnecessary addition, as it is more a client requirement and a habit in the construction practice, Fig. 11 Barriers of construction 3D printing in solving the problem of dust/silica dust exposure -Limited project size/ Limited applicationssurvey results

Fig. 12
Barriers of construction 3D printing in solving the problem of dust/silica dust exposure -Price/ Lack of awareness -survey results rather than a necessity as 3D printed walls come with a specific finish created as a result of the printing process. This might not be acceptable to some clients.
"After-print activities like plastering or ornamental installations could have more exposure risk than the print itself." (Interviewee 10).
Contrary to the literature and survey findings price and lack of awareness were included as barriers for construction 3D printing by 1 interview participant and 2 respectively. Also, from the interview survey, innovation resistance was considered quite important or very important by 60% or respondents but was mentioned by only 1 interview participant. This can probably be explained by the fact that the interview participants are already working or have connexions in the 3D printing industry, dealing with eager clients and co-workers, and therefore it did not naturally come to mind as a barrier. Contrary to the literature and the researcher's expectation, the new health risks posed by this was mentioned by only 2 participants and almost 40% of the interview survey participants were either unsure or considered it not important. The most important barriers for construction 3D printing in solving the problem of dust/silica dust exposure are presented in Fig. 13.

Strategies for wider adoption of construction 3D printing to minimise the incidence of long latency respiratory disease among construction workers
Findings from the literature In order to identify the strategies to promote the use of 3D printing in the context of health, the literature was reviewed. The main strategies indicated in the literature focus on the support of architects having this method in mind when designing (Olsson et al. 2021), the contribution of a lifecycle analysis for 3D printed buildings, better developed regulations (Olsson et al. 2021) and the pressure of sustainability and waste reduction (Achillas et al. 2015). The novelty of the 3D printing technology brings numerous challenges when it comes to a wider adoption and will most probably require a certain level of shock or coercion. This can take the form of a governmental mandatory requirement or an exhaustive analysis of how it can help the construction workers, which otherwise are prone to occupational ill health.
Findings from questionnaire In order to identify the strategies for a wider adoption of construction 3D printing in the minimisation of onsite dust/ silica dust exposure, a question The responses for the survey showed that 86% of the participants consider the need for sustainability as quite important or very important strategy to promote construction 3D printing, followed by lifecycle analysis with 79%. Improved regulations were considered quite important or very important by 72% of the participants and architects are believed to play quite an important or a very important role in promoting the use of this technology. These align with the findings identified in the literature. Improved regulation makes this construction method safer, being safer it can be used more, being used more there are more projects, and more lifecycle analyses can be carried out to emphasize the benefits not just for waste reduction and sustainability, but for health as well.

Findings from interviews
The feedback from the interviews, as summarised in Fig. 16, identified the top three most effective strategies in promoting a wider adoption of 3D printing as solid legislation, pressure from the need of sustainable construction methods and affordability. These results were highlighted by 6, 5 and 4 interviewees respectively out of 18. Although only one interviewee mentioned the high price for 3D printers for construction as a barrier, the issue of affordability was mentioned by 4 interviewees as necessary to be resolved in order to promote the adoption of this construction method.
Making the 3D printing process fully automated was brought up in the interviews. To Interviewee 13's point, this would tackle the problem the mixing technicians are facing at the moment, meaning, having to handle powdered materials in preparation for the printing process and which does not help in preventing respiratory diseases. The technology has to prove itself as a fully automated, cost-effective, rapid and sustainable way of construction." (Interviewee 2). "An enclosed system/machine to mix the raw materials." (Interviewee 13).
Based on the literature, it was expected to see the role of architects to be considered quite important, but the results of the interview do not support this idea to the anticipated level.
Interviewee 4 highlighted a very important aspect regarding the adoption of 3D printing from a health point of view, by stating that it will be driven by commercial gain or governmental coercion. History teaches that the principle of doing the right thing was very rarely enough to determine a drastic change or shift in mentality.
"Being realistic and perhaps slightly cynical, nobody will adopt the technology in order to protect workers from dust exposure. Like everything else in this industry, adoption will be driven by commercial advantages and legislative pressures." (Interviewee 4).
A similar view is shared by Interviewee 7, expressed in the following excerpt: "It needs to bring economic and ecological benefits at first to be widely adopted in the industry." (Interviewee 7).
A realistic approach will have to take all these facets into consideration to ensure a successful result can be attained.
As highlighted by Interviewee 4, raised awareness can have a high impact on the demand for this construction method. It can educate the potential clients, the architects, contractors and other parties on the benefits from both a health and sustainability perspective.
"Raise awareness of the benefits, processes and procedures for implementing 3DCP technology to demystify it and increase familiarity within the marketplace." (Interviewee 4).
Furthermore, as the demand increases so will the need for the legislation to adapt to the new market conditions, as highlighted by Interviewee 10. This aligns with the findings from the literature, and it can be stated that as the rules become clearer, more players will play. The more it will be used, the more research can be done based on lifecycle analysis to investigate the impact on workers' health, labour market, sustainability, time and costs to build using this technology.
"Research & development generating in-off data to get the technology approved by the construction codes of each country, as well as keep upgrading the technology to become a more affordable & environmentally friendly." (Interviewee 10).

Fig. 16
Strategies to promote a wider adoption of 3D printing in construction to reduce exposure dust/silica dust exposure as resulted from the structured interviews

Summary of findings and discussions
The study succeeded in engaging a sufficient number of participants for the questionnair survey and interview. The survey and interview participants had a significant contribution in understanding to what degree 3D printing can help reduce the incidence of long latency respiratory diseases caused by dust/silica dust among construction workers in the construction practice.
Both survey and interview participants considered the most important existing measures in managing the problem of dust onsite to be the respiratory protective equipment and dust removal systems, corroborating literature findings emphasised in a study carried out by Institution of Occupational Safety and Health (2014). The interview participants include 3D printing on the third place, but a high number of respondents representing almost 30% were unsure about the potential of construction 3D printing. Therefore, it can be concluded that 3D printing cannot be seen as an absolute solution to solve the problem of onsite dust exposure, but with a fully automated process, it can have a significant contribution in resolving this aspect.
The questionnaire survey revealed the demolition operatives and construction workers are the categories with the highest risk of exposure to dust which aligns with the literature findings (Mølgaard et al. 2013). The interviews brought other two categories into discussion: the neighbours and the mixing technicians who prepare the powder-based materials to go into the concrete 3D printing machine.
In terms of the benefits of this new technology from a health perspective, if was identified that the printing process needs to become fully automated to have a significant chance in addressing the problem of reducing respiratory diseases among the workers. This will reduce the number of operatives needed onsite, their contact with the material mixing process and a more controlled environment to carry out the works. The interview responses include the avoidance of cutting concrete and cutting grooves as benefits worth considering.The survey identified a number of limitations of construction 3D printing applications, together with lack of awareness about the negative impact of dust on health and high price to be the main barriers in addressing the problem of onsite dust exposure. The feedback from the interviews identified the mixing process and the lack of regulations as top two most important barriers.
In terms of the strategies to promote the use of this technology, the survey participants consider the need for sustainability, carrying out a lifecycle analysis and improved legislation as the most important, in line with the literature findings emphasised in Olsson et al. (2021) to which the interview responses added the printing process becoming fully automated and the price for the equipment to become more economical.

Conclusions
The aim of this research is to address the problem of occupational respiratory diseases caused by dust/silica dust among construction workers, investigate the implementations of 3D printing in the construction industry and its potential implications in decreasing the incidence of some of these diseases.
In order to address the research objectives, secondary and primary data was collected, and a mixed research approach was used. The existing literature was reviewed to gain a deep understanding of the intricacies of the new technology. Additionally, an online questionnaire survey was carried out, together with a set of interviews which provided valuable contributions, based on the interviewees' experience. Through the implementation of the research methods, the established research objectives were attained. These include the identification of the: most prevalent respiratory diseases in construction, strategies of minimising onsite dust/ silica dust exposure, benefits of 3D printing in the minimisation of onsite dust/ silica dust exposure, barriers of 3D printing in the minimisation of onsite dust/ silica dust exposure, strategies for the wider adoption of construction 3D printing to minimise the incidence of long latency respiratory disease among construction workers.
The study engaged participants to think about the potential of this new technology and the benefits not only from a sustainability perspective but also health. The novelty of the technology might not allow this study to present absolute results, but it brings to mind an aspect which can be explored further as the technology develops. This study highlighted the potential of this new technology from a different perspective, considering ways to overcome the challenges that come with it.
This study is useful for companies who are preoccupied with the matter of health and safety and aim to reduce the impact of their economic activity on their employees. It can be considered equally important for improving the policies in the health and safety sector and funding allocation for helping companies incorporate innovative technologies in their activity.
A number of potential future research directions were identified. Additional work is required in order to understand the costs implied by changing the construction methods in a UK based construction project, how 3D printing will impact the delivery time for the project and what design methods can be developed to facilitate the wider adoption of this technology.
Further research could be conducted to identify the impact of dust exposure on the neighbours around the construction site. Once the industry reached a higher level of maturity, a continuation to the current study would be to carry out medical research to measure the lung function and concentration of dust/silica dust in the lungs for a group of construction operatives who worked on projects using construction 3D printing. This will provide more accurate information in terms of the impact of 3D printing on reducing the incidence of long latency respiratory diseases caused by dust/silica dust among construction workers.