Multistage Optimization of Occupational Safety for Cotton Fabric Screen Printing Press Operators

ABSTRACT The aim of this article is to conduct an analysis leading to the optimization of industrial safety related to the use of a cotton fabric automatic screen printing press. The author’s multistage algorithm, i.e., the analysis-synthesis-minimization procedure, brings effective solutions to the issue in question. There are several risk factors at the printing press workstation and its environment, which are identified by employee surveys, scorecards and airborne samples testing. The risks are visualized by the fishbone/Ishikawa diagram. In accordance with the Fine–Kinney method, a set of 70 scorecards assessing occupational risk is applied to support the identification of critical hazards, which is next re-analyzed using the Analytic Hierarchy Process (AHP). Hierarchically assessed risk factors related to the use of a printing press are easy to be minimized by organizational and technical solutions which are intended to be implemented at the workplace.

process. Various patterns and shapes can be printed using the screen printing technique. The set of parameters affects the outcomes of the process and the quality of the deposited layer. Paints used in fabric printing require heat fixing to become wash proof. Any type of heating device can be used for this purpose, i.e., heat tunnels or kilns. Cotton fabrics should be heated for 4-5 min at 140-180°C, according to Anonymous (2022b).
The automatic press for the screen printing process has many advantages. It makes printing fast and inexpensive on an industrial scale. It can be universally applied to many types of substrates, including surfaces of irregular shapes. Printing pastes for the automatic press are considerably cheaper than toners for digital printing; they are also characterized by stability and resistance to weather conditions. Furthermore, the automatic press operator can create own range of colors by mixing the pastes. Finally, the printing surface format is limited only by the machine parameters.
This way of printing, however, also has several disadvantages, mainly environmental. The printing pastes are aggressive chemical substances, and the automatic screen printing technological process generates large amounts of waste. Chemicals used in printing are substances that may be harmful to health when it comes to uncontrolled exposure. Contact with the chemicals can cause skin problems; they may also be absorbed through the skin or by inhalation and cause damage to other parts of the body (Health and Safety Executive, 2022).
The technological development of screen printing is slow and the printing procedure still takes significant time in terms of proper preparation of materials and chemicals. There are a few types of printing pastes used for screen printing. Each paste is characterized by different properties and therefore -different methods of fixation. Thus, the selection of a printing paste to a substrate requires knowledge of various technological parameters. Kiurski et al. (2016) examined occupational pollutants types as well as the adverse impacts of the printing process considering various printing techniques. Printing workers are exposed to occupational hazards. Unfortunately, the problem is rarely analyzed in scientific works. Various physical, chemical and psychosocial risks in the printing industry have been discussed in Collective work (2012).
Comprehensive analysis should be supplemented by an appropriate competency training. Mohamed Abd El-Maksoud and Abdel-Latif Ali (2020) investigated the perception of occupational hazards and safety measures among printing workers. The results revealed that the majority of workers were exposed to moderate levels of occupational health hazards and experienced insufficient safety measures. The most emphasized are health-related hazards, such as injuries or results of exposure to chemicals, along with psychological hazards.
To identify behavioral factors associated with the prevalence of acute symptoms, a cross-sectional study was conducted by Decharat (2014). There were associations found between personal protective equipment, personal hygiene and the prevalence of acute symptoms.
Work-related musculoskeletal disorder was analyzed by Fadillah and Muslim (2019) in the screen printing department, where the workers' working postures were evaluated. The results show that workers may be subjected to low-to middle-high injury risk.

Stryker M&R automatic screen printing press
STRYKER M&R automatic screen printing press (cf. Anonymous 2022b) is used by a small company operating in Lodz, Poland. The firm specializes in a full clothing production process, from design, through sewing to final operations. The company also produces advertising materials such as stickers, flags and patches. It develops mainly screen printing on cotton fabrics. The company employs 40 people in various job positions. The analysis is focused on production workers operating the screen printing press. This is a stationary, single-shift job position. Working time includes one 30-min break per day.
The printing press is located in a work environment in which all materials and chemicals necessary for the technological process are present, Figure 1. It stays in the close vicinity of chemicals, without any additional protective measures (there is no warehouse for the chemicals, the ventilation in the facility is limited). Storage of chemicals is likely to be the main hazard as it comes to working on a screen printing press. The main goal is to optimize the work safety of screen printing press operators by applying a multistage procedure. At the analysis stage, the hazards are identified using (i) an employee survey, and (ii) airborne sampling and testing of hazardous substances at the workstation as well as its surroundings, next systematized by the Ishikawa diagram. The synthesis stage consists in determining the occupational risk with the use of scorecards, and then relating it to the acceptable risk result for the analyzed position, which is consistent with the Fine-Kinney method. The critical hazards are next reanalyzed by the Analytic Hierarchy Process in order to create their hierarchical assessment. At the last minimization stage, the unacceptable risks can be efficiently reduced using organizational and technical operations. The newly introduced components are the following: (i) the presented procedure is the author's algorithm. No publications describing critical risks identification by the Fine-Kinney method and its following re-analysis using the AHP assessment were found; (ii) the hierarchical arrangement of critical risks allows to introduce a set of diversified organizational and engineering solutions corresponding to the hazard rank and the possibility of implementation.

General algorithm of risk minimization procedure
In the research presented below, the risk minimization procedure can be divided into three basic steps, i.e., the analysis, the synthesis and the risk minimization ( Figure 2).

Analysis stage: Identification of occupational risk
The occupational risk should be assessed by all aspects of work to determine the hazards that could cause occupational injuries or deterioration of the health of employees. The hazards should be eliminated to the largest possible extent and the occupational risk minimized to the admissible level. We use an employee survey and measurements of hazardous substances to identify the hazards at the workplace and in its surroundings.

Survey among employees
The survey consists of six parts and was dedicated to the production workers on the automatic screen printing press. The first part is devoted to the general characteristics of the workplace and introduces the following elements: (i) short description of the workplace, technology and type of production, basic equipment, its elements, materials, division into zones and their safety ranges; (ii) number of employees at the workplace; (iii) working conditions and any existing restrictions on these conditions; (iv) global working time of the printing press; (v) detailed working hours per day of the production workers at the printing press. The second part provides information about the regulatory requirements at STRYKER M&R printing press, particularly: description of the OSH training, preventive medical examinations and the competence to work at the given position.
The third part includes a detailed assessment of the accidents and occupational diseases: (i) number of accidents at work, and the time of their occurrence; (ii) identification of the accidents causes and their categories; and (iii) number and types of occupational diseases.
Identification of physical hazards at the workplace (the fourth part) introduces 34 types of hazards and a short description of the protective equipment against the risks.
The fifth part is devoted to chemical substances and their mixtures. Table 10 -inserted in the further part of this study -corresponds to the fifth part.
The last stage refers to the biological hazards, i.e., (i) the type of hazard (bacteria, viruses, parasites, fungi, plants, animals); (ii) the name of a particular biological agent; and (iii) the group of biological agents and protective equipment used to reduce the risk.

Measurements of hazardous substances at workplace
Hazardous substances were recognized by using air samples from the workplace. The samples were taken during the entire work cycle of the screen printing press: loading and removing the substrate (cotton fabric) for printing, putting the substrate into the tunnel kiln, as well as during preprocessing.
The chemicals applied during screen printing were classified as aggressive, e.g., plastisol printing pastes, the solvents BIROL and TAKTER 2000 which are based on acetone and toluene ( Table 1).

The Fishbone/Ishikawa diagram
The fishbone/Ishikawa diagram is a graphic technique to visualize, systematize and analyze several causes of a specific event or phenomenon (cf. Coccia, 2018). The diagram is commonly used as Relative expanded uncertainty for the coverage factor k = 2, which corresponds to the confidence level of about 95%, includes the sampling stage and the laboratory analysis stage. The concentrations in mg/m 3 apply to the temperature 20°C and pressure 1013 hPa. The values are converted from temperature 30.35°C and pressure 987.1 hPa. The symbol "p" indicates that the concentration inside the sample is below the value following this symbol (method limitation). a cause-and-effects analysis to identify a complex interplay of causes and events. The hazardous situation was identified using the four main stages: (i) problem identification, (ii) determination of the main cause of an emergency event, (iii) identification of other possible causes of an emergency event, and (iv) creation of the diagram and its analysis.
The causes of hazardous situations are usually divided into several main categories: human factor, workplace operation methods, machines applied, materials, measurements taken during work and environmental conditions. Current systematization helps to identify the causes of an emergency event, accidents at work and the correspondence between causes and effects.
The Ishikawa diagram presents a graphical relationship between particular factors/fragmentary events and the final/hazardous event. The main cause of an analyzed situation is pictured as the "fish head" and the remaining, potential causes are arranged in the form of "fish bones." The diagram shows the connections between the identified problem and the considered causes of the emergency event, see, for example, Liliana (2016). Thus, the diagram is a graph illustrating sequence of events and their gradation ( Figure 3).

Synthesis stage: Hierarchical description of critical risks
The identified risks were next introduced into the synthesis stage to determine the hierarchy of hazards. The Fine-Kinney method was applied to define global risks at the workplace and identify the critical ones, i.e., risks that are above the acceptable level. The set of scorecards helped to systematize the obtained results and define the most critical risk as the input data to the AHP. The efficiency of AHP is closely correlated with the number of analyzed risks.

Application of the Fine-Kinney method
Muhammet Fatih (2020) compared the risk assessment methods used in the hazards analysis to create a proactive approach to accidents prevention. According to analysis, the Fine-Kinney method and AHP are the most efficient procedures. Gul, Guneri, and Baskan (2018) applied the risk assessment in the construction and operation of wind turbines. The analytical hierarchy process was applied to assign weights to the parameters of the Fine-Kinney method. Some authors proposed new weights in the Fine-Kinney procedure, cf. Oturakçi, Dağsuyu, and Kokangül (2015). Netro, Romero, and Flores (2018) assessed the risk factors using the adapted Fine-Kinney method. The adaptation included adjustment on the occurrence scale to consider the general degree of incidence, and on the severity scale to consider the number of impacts.
The Fine-Kinney method is a procedure of risk estimation based on three parameters: the probability P, exposure time E, and possible severity of injury S. The analysis is focused on the occupational risks caused by STRYKER M&R screen printing press, the preparatory and final operations, and the compatibility between the presence of the production worker in the company and an appropriate level of occupational safety provided by the employer. The global risk value at the workplace was determined by multiplying these parameters. (1) The factors were determined according to the Tables 2-4. The tables were developed on the basis of previous references as well as own analyses. Occupational risk at the workplace was calculated as an arithmetic mean of all risk values for individual hazards and rounded to the nearest whole number, as presented in Table 5.

Scorecards assessment of the occupational risk
The analysis is based on a set of 70 scorecards which determined the current (for then) safety status. The set is developed on the basis of the previous risk identification and supplemented by additional Highly probable accident, chance of more than 50% 6 Relatively probable accident, chance of around 10-15% 3 Accident may occur, chance of about 1-2% 1 Low accident probability, chance of 10 −1 % 0.5 Occasional accident probability, chance of 10 −2 % 0.1-0.2 Imaginable probability of an accident, chance of 10 −4 −10 −3 % information obtained from employees, company owners as well as individual observations and conclusions. The observations concern the most noticeable errors while working on the screen printing press in the areas of the machine/worker's workstation as well as while working with hazardous substances. An example is shown in Table 6. The scorecards mainly describe operating of the following devices: STRYKER M&R screen printing press, Sprint 2000 kiln, Polar N78 PLUS cutter, HOT-HEAD device for smoothing the pattern, a print pastes stirring tank, a compressor, SV 6595 sieve dryer, a mesh tensioning table, a scoop coater, a UV coating machine, a drilling machine, a hand eyelet machine. The other cards concern auxiliary information, e.g., loading and warehouse activities. The last category was focused on pedestrian safety, transport, self-preparation of food and the general presence in the facility. The above described risk identification at the workplace as well as the application of the occupational risk assessment cards allowed to incorporate the AHP. High risk at the workplace, immediate improvement of working conditions is necessary 70 < R ≤ 200 Significant risk at the workplace, immediate control of working conditions is necessary 20 < R ≤ 70 Low risk at the workplace, control of working conditions is required R ≤ 20 Acceptable risk at the workplace, control of working conditions is recommended

Application of the Analytical Hierarchy Process
AHP is an efficient method when a limited number of hazards are involved. Hereby, we introduce the risks at an unacceptable level assigned by the Fine-Kinney method to R > 70 categories (i.e., substantial risk; high risk; very high risk). The AHP method was developed by Saaty (1980) and is applied as a hierarchical decision-reaching procedure, cf., for example, Kokangül, Polat, and Dagsuyu (2016) who proposed the risk management modeling for the bus manufacturing supply chain. AHP was adopted to create hierarchy among suppliers. Oturakci (2019) introduced fuzzy-based approaches for environmental risk assessment connected with AHP. According to the application in the chemical branch of a textile company, the new approach minimized the subjectivity of assessment. AHP is defined as the following sequence: the problem -main goal of implementation -main criteria -other criteria -alternatives. The analysis can be visualized as a hierarchical tree of hazards. Interactions between the criteria and alternatives are determined using the intensities, as in Table 7, and comparison matrices.
Based on the Fine-Kinney method, occupational health and safety experts could estimate which risks need more emergent precautions. Two experts involved in this research worked in occupational safety engineering; Expert 1 for more than 30 years as a coordinator of occupational safety works, Expert 2 for 5 years, mostly dealing with equipment observation.
Let us normalize and classify the AHP scores based on the Fine-Kinney risk classification. The hazards according to AHP range between 0 and 1; according to Fine-Kinney -between 0.5 and 10,000. The minimum score is assumed to be equal to 0. To normalize the maximum scores, the value 1 in AHP was taken as 10,000 in Fine-Kinney, cf. also Kokangül, Polat, and Dagsuyu (2016). The normalized class limits in AHP are shown in Table 7.
The risk categories are classified into 3 levels as shown in Figure 4. The risks at the 1st level are classified using the general definitions in the 3 categories: chemical, ergonomic and thermal. The 2nd level is represented by two hazard categories identified using the Fine-Kinney method. At the 3rd level, 8 types of risks are approximated as the corresponding elementary hazards. The AHP score at the third level is determined by the scores from the 1st and 2nd levels. Thus, the risk estimation at this stage includes all previous levels and is representative as a global risk assessment.
The problem becomes significantly simplified due to the analysis of work at the screen printing press limited to the most unfavorable cases, with the highest level of risk determined by the Fine-Kinney method. The results are demonstrated in Table 8.
Both experts have estimated the AHP score with a 3 decimal places accuracy, the average value is the arithmetic mean. The AHP evaluates the selected risks that may have additional context. Therefore, the assessment of any risk in special cases could be additionally related to the Fine-Kinney method as a basic one. Most of the AHP scores were assessed by experts at the same level. Larger differences can be found at level 1 (cases 1, 2) and level 3 (cases 1, 3, 4). The deviations can be explained in case 3.3: the essential part of the ventilation system is installed outside, which affects the operation; and 3.7: regardless of the disorder, all packages contain appropriate labels. Therefore, both cases were assessed differently.
The consistency and aggregation of the experts' judgments are confirmed by the maximal principal eigenvalue λ max and the consistency index CI. The reciprocal matrices from paired comparisons are defined for each expert at levels 1, 2, 3; and next transformed to the normalized relative matrices. The calculations show that all normalized matrices have the same row elements. Thus, the normalized principal eigenvector has the simple form and the maximal eigenvalue λ max is always equal to the matrix size n (at level 1: n = 3; level 2: n = 2; level 3: n = 8). Saaty (1980) has proved that for the consistent reciprocal matrix, the largest eigenvalue is equal to the size of comparison matrix λ max = n. The measure of consistency is the consistency index CI defined as deviation or degree of consistency according to the formula.
The values of CI are equal to zero in all cases, i.e., there are no consistency deviations. It is difficult to determine the statistical tests because the AHP procedure contains a relatively small number of components.
The obtained results show that the most significant risks of AHP score are at the 3rd level: 3.4 Inadequate technical conditions in storage areas (0.3210); 3.1 Exposure without protective equipment (0.3045); and 3.7 Disorder at the workplace (0.1530). Consecutive: 3.5 Unsatisfactory concentration at work (0.0800); 3.2 Exposure above the recommended limit (0.0640); and 3.8 Contact with a hot kiln (0.0570) are assessed at the medium risk level. Two last cases: 3.6 Ignorance when handling hazardous substances (0.0170); 3.3 Failure in the ventilation system (0.0035) are relatively insignificant in relation to other risks. The results of hierarchical systematization allow to significantly reduce the identified risk and optimize the working conditions using certain organizational and technical means of action.  The corresponding risk at the 1st level: C -chemical; E -ergonomic; T -thermal.

Safe storage of substances and application of personal protective equipment (PPE)
Investments described below could significantly reduce the risks defined in ranks 1-3. The preparation cost of a small room for the safe storage of chemicals with dedicated racks, ventilation and protection system costs roughly (3000-4000) USD. The costs of the health and safety training are about 1000 USD, the PPEs -about (300-400) USD/year. The current (for then) situation concerning safe storage of chemicals and application of PPE at the company was highly unsatisfactory and should be radically changed. Production workers were exposed to many chemical substances, including aggressive printing pastes, solvents on the basis of toluene and other chemical mixtures exhibiting harmful properties. According to the survey among employees-, the production workers were in contact with flammable and caustic substances as well as irritants. The harmful effects of toluene were particularly troublesome. Unfortunately, the chemicals were found around the workstation and over the factory in incidental places. The chemicals were stored in commercial racks located directly next to the press. The employees were not fully aware of the applied chemicals, and -what follows -had no knowledge of the dangers caused by their incorrect storage. Additionally, the workers had no knowledge on the location and content of Safety Data Sheets (SDS).
According to the analysis, the problem requires radical changes. The proposed solution is to organize a specialized health and safety training with particular emphasis on working with dangerous substances and chemicals as well as the introduction of SDS. Additionally, it is absolutely necessary to organize a small room for the safe storage of chemicals, taking the storage conditions requirements (corresponding to properties) into account. Chemical substances should be stored on special racks dedicated only for this purpose and properly marked. The pictograms concerning physical, chemical and environmental hazards are listed in Table 9, whereas storage rules for hazardous substances gradated according to the effect on humans are presented in Table 10 (inspired by Liliana 2016).
Regardless of the seriousness of the situation and health hazards, the production workers at the screen printing press worked mostly without the PPEs. The employees were unaware that the application of the personal protection was advisable and necessary, particularly as far as the eye, face, skin and respiratory protective equipment is concerned. The issue should have been solved immediately by organizing a special training for employees, see above.

Service manual for the safe and hygienic operation of the screen printing press
Correctly prepared service manual can significantly reduce the risks defined at ranks 2-6 and 8. The cost of preparing a manual is low -around 100-200 USD. The current (for then) documentation on servicing and operating the screen printing press did not meet the requirements for this type of manuals. Thus, it is imperative to re-write the existing service manual in order to make documentation correct. The automatic STRYKER M&R screen printing press includes an internal safety system with the blocking system which is active in some predefined cases. The workplace hazards are reduced by improving the safety of the area around the working machine. The press should be used according to the intended purpose, with particular emphasis on the principles of work safety.
The improved service manual should familiarize an employee with the basic information on the safe operation of STRYKER M&R printing press. It was established that the document should contain the following information: (i) duties of the person responsible for managing employees; (ii) information on the safe and hygienic machine operation and work execution; (iii) activities performed before starting and after finishing work on the press; (iv) operations prohibited during work at the wokrstation and in its surroundings; (v) proceeding methods in dangerous and emergency situations as well as at the fire hazards; (vi) other general or final comments providing essential and procedural data on the work at the screen printing press.

Implementation of the 5S System
The 5S System should be implemented at the workplace to minimize disorder and improve selforganization. The system helps to determine proper organization at the workplace and its environment, and increase the global industrial safety and productivity. The 5S strategy helps to reduce all hazards at the workplace as a global management system. The system is iterative, globally oriented, requires specific procedures and gradual implementation throughout the plant. Therefore, the costs apply to the entire company and cannot be estimated for a single screen printing press. The first stage of the 5S System is Sort. In the case of the screen printing press located in the analyzed factory, the following principles are intended for implementation. (i) Each employee should keep order at the workplace; it applies to the right selection of tools, raw materials, chemicals, etc., as well as relocation of unnecessary materials on, e.g., racks intended for this purpose. Chemicals and aggressive substances should be stored inside a special room, meeting storage conditions. (ii) Each production worker should be subjected to periodic job rotation and controlled until returning to the original position.
implemented working conditions can be performed. It is necessary to maintain order during the work and after completion of all the activities at the workplace. This stage should be permanently improved and open to employee suggestions. Shine is the third stage of the system in question. The main idea is to be devoted to maintaining order at the workstation and its surrounding during the last minutes/last hour of work.
The 4th stage Standardize is focused on accepting all previous steps and working according to the introduced arrangements, standards and procedures. Information within a workplace should be delivered in an easy and transparent manner. Access to information is particularly important during the operation of screen printing press as well as during the arrangement of raw materials and chemicals.
The 5th and the last stage is Sustain. This action is aimed at developing new habits of employees and procedures necessary to comply with new solutions and standards. Thus, sustainability to a significant extent is determined as a part of the permanent self-improvement process within the facility.

Limited contact with hot surfaces
Limited contact with hot surfaces prevents the risk of rank 7. Kiln thermal insulation is effective and the external temperature of casing is safe for the operator. Contact with the heated internal surfaces constitutes a hazard, when the device is open and no protective gloves are used by the operator. Estimated costs of safety-improving solutions implementation in this field are insignificant, at around 300-400 USD.
Due to relatively scarce and short-term hazard, solving the problem may be optionally taken into consideration. It is possible to install a temperature sensor. It is mandatory for the operator to use PPE which protects against heat exposure -thermal gloves. The kiln can only be opened when the temperature received by the sensor is lower than that of the human body, i.e., when the operator uses protective gloves. Temperature comparable or higher than 34-36°C (i.e., the average skin temperature) causes the device to remain locked.

Summarizing survey among employees
The summarizing survey consisted of two parts and was intended for production employees on the position of screen printing press operator. The first question concerned the acceptance of organizational and technical amendments with the exception of the 5S System. A vast majority of respondents were in favor of introducing the proposed changes. There are many irritants present during the technological process and the application of the basic PPEs (mainly hand and face protection) would significantly increase the comfort of work and protect employees from possible side effects of the chemicals used. The second part of the survey concerned the implementation of 5S System. The majority of survey participants clearly expressed their support for incorporation of this procedure. The motivations were defined as follows: the 5S system involves all employees to maintain order at the workplace and its surroundings, introduces new habits at work and contributes to creating a safer workplace.

Conclusions
Workplace hazards are usually analyzed using a single risk assessment method, predominantly the Fine-Kinney method or AHP. According to the literature, both are the most efficient procedures. In the paper presented, the work safety -at STRYKER M&R screen printing press was optimized by the author's multistage algorithm. The main idea was to determine the most critical risks using the Fine-Kinney method and then re-analyze them using the AHP. The hierarchical assessment of critical risks according to AHP allows to apply a set of diversified organizational and technical operations corresponding to the rank of hazard and the possibility of application.
The advantages of the developed procedure are as follows: the global analysis of a fundamental occupational safety problem, its significant simplification and a shortened analysis time. The Fine-Kinney method alone can be inefficient in the case of many risks of unclear interactions. The hierarchical assessment involved in AHP is time-and labor-consuming, as a global analysis of a workplace and its environment is complex due to a network of interconnections between hazards. Thus, the risks were estimated according to the Fine-Kinney method which is considerably simpler and effective enough. The hazards are analyzed without network of connections between particular types of risk at different levels. The AHP is efficient in the case of hazards limited to the critical level and the network can be simply created for the reduced number of relationships.
The disadvantage can be the limitation of the hierarchical risk specified by AHP to the cases predefined by Fine-Kinney analysis. However, precise and complex analysis using the Fine-Kinney method significantly reduces these limitations. Shortened analysis time and simple logical procedure are much more effective than the risks assessed by a single method used so far.
The procedure is supplemented by a set of diversified organizational and engineering operations during the risk optimization stage. These activities are defined for the specific workplace, i.e., STRYKER M&R screen printing press in the specific company. According to the summarizing survey, a large majority of employees supported the introduction of these changes, including the stepwise application of the 5S System.
The global cost of such amendments constitutes a problem. The analysis according to the multistage analysis-synthesis-minimization algorithm does not generate any costs. The investment outlays are generated by some organizational and engineering activities and can be estimated globally at 4700-6000 USD. An additional cost is associated with the 5S System. Its introduction applies to the entire facility and it is not possible to limit the cost to only one workstation such as the screen printing press. The costs are very high, the time to implement the 5S system is relatively long, but the benefits on a global scale are very significant. The procedure allows to redefine the system of work and arrangement of materials, tools, etc. at the workplace. The system was intended for implementation in the above analyzed company. The benefits of the proposed changes were listed in Table 11. Optimization procedure Benefits Assessment of the occupational risk at the workplace Employees are familiarized with the hazards at the workplace and are much more aware of the occupational risk.
The global safety at the workplace and in surrounding grows significantly. Improved service manuals on the safe and hygienic work at the screen printing press Production workers are familiarized with the work regime, the list of activities and duties using an understandable method. Improved method for safe storage of chemical and aggressive substances Employees are much more aware of the occupational risk concerning the inappropriate storage of substances. The order is kept and secured at the workplace and in company. The load capacity of the racks is correctly marked. Undesirable effects at the workplace are reduced. Implementation of personal protective equipment Employees are protected against the hazards at the workplace and in environment.

Implementation of 5S System
The order is kept and secured at the workplace and in company. The number of accidents caused by employee inattention is reduced. Productivity and work efficiency is increased. Raw materials, materials and tools are identified faster. The company is organized and operates in standardized and systematic manner. Limited contact with hot surfaces Preventive treatment against skin burns caused by a contact with the hot surface of the furnace.
The optimization of industrial safety at the automatic screen printing press can be developed using the mathematical tools and computer analysis as a permanently self-learning system. Some optimization methods can be also implemented, cf. the particular objective functional connected with the variational approach of optimization procedure which can be solved using any computer procedure (see, e.g., Szafranska 2016, 2017;Maślanka and Korycki 2022) or the elements of statistical analysis (cf. Szafranska and Korycki 2020).

Disclosure statement
No potential conflict of interest was reported by the authors.

Highlights
• The work safety at the screen printing press was optimized using a multistage procedure. The presented procedure is author's algorithm. No publications describing the determination of the critical risks by the Fine-Kinney method and following its re-analysis using the AHP hierarchical assessment were found. At the analysis stage, the main hazards are identified using (i) the survey among employees; (ii) the airborne sampling and testing of hazardous substances at the workplace and its surrounding, and next systematized by means of the fishbone/Ishikawa diagram. The synthesis stage consists in defining occupational risk by scorecards and then related to the acceptable risk score at the analyzed position what is consistent with the Fine-Kinney method. The critical hazards are next re-analyzed by the Analytic Hierarchical Process in order to create their hierarchical assessment. • The hierarchical arrangement of critical risks allows to introduce a set of diversified organizational and engineering solutions corresponding to the rank of hazard and possibility of application. • The global analysis of a fundamental occupational safety problem is significantly simplified, the analysis time is shortened. The single Fine-Kinney method can be inefficient in case of many risks of unclear interactions. The hieratic assessment according to AHP is time-and labor-consuming, the global analysis at the workplace and its environment is complex because of a network of interconnections between hazards. Thus, the risks were estimated according to the Fine-Kinney method which is considerably simpler and effective enough. The hazards are analyzed without network of connections between particular types of risk at different levels. The AHP is efficient in case of hazards limited to the critical level, and the network can be simply created for the reduced number of relationships.