Air purifiers, comparison between real and declared surface for use: fake it or make it?

Abstract Introduction Air pollution has been recognized as one of the major risk factors for the global burden of disease. In modern society, most exposure occurs indoors, and air quality may be improved with air purifiers utilizing various cleaning techniques. This analysis aims to evaluate whether recommended room surface in which to use these devices as declared by producers is actually in line with their real effective area of activity. Methods A review of devices for the purification of the air was carried out between January-April 2022. Four different types of air purifiers were considered based on the adopted technologies: I) HEPA filters and UV lamps; II) only with HEPA filters; III) only UV lamps and IV) those using other technologies. For each group, based on the CADR (Clean Air Delivery Rate) provided by the producers, the optimal real surface area of the room to use the device was calculated, referring to the standard EN779:2012. This value was compared with the recommended area of the room declared by the producers. Descriptive statistics and Wilcoxon matched pair test used for comparisons. The significance level was set at p < 0.05. Results The analysis was carried out on 252 devices; I) 52 had HEPA filters + UV lamps, with a recommended mean room area of 40 m2 (IQR 49.75), II) 142 devices had only HEPA filters with 52.5 m2 (IQR 46.75), III) 27 devices only UV lamps, 40 m2 (IQR 105), IV) 31 devices with other technologies, 54 m2 (IQR 84.2). As required by EN779:2012, the effective area of activity was calculated using CADR x 0.075: the medians of the 4 groups were I) 12 m2 (IQR 16.5), II) 15.83 m2 (IQR 26.4), III) 4.5 m2 (IQR 22.5), IV) 7.5 m2 (IQR 21.53), respectively. Comparing declared and calculated CADR values, all the groups showed significant differences (p < 0.05). Conclusions Results show that recommended surfaces derived from CADR declared by producers largely overestimate the real volume of the room that devices can purify, whatever the technology used. Key messages • There’s no correspondence between recommended area of room to be sanitized indicated by producers of air purifiers and area that they are actually able to sanitize, which is significantly lower. • It is necessary to be aware of the difference between data indicated by producers and real data, in order to purchase a device that actually corresponds to dimensional needs of the environment itself.


Background:
Each year, numerous initiatives are carried out to improve the outcomes for youth living in vulnerable areas. However, the impact of these initiatives is rarely measured, partly because there is no reliable, valid, relevant and easy-to-use tool available to measure the impact of social investments from the youth perspective. Mina Svar is an app co-created with youth that aims to address this gap. Methods and results: Save the Children led the collaboration in defining a measurement framework. Experts from Save the Children, researchers from Linköping University, and representatives from Accenture, Skandia and Apoteket as well as youth themselves were involved in an iterative process. Five interconnected areas were identified as central: democracy and influence, education, work, housing and neighbourhood, and health. The first version of Mina Svar included 34 items. Researchers from Uppsala University were involved to help with testing the psychometric properties of Mina Svar in a sample of 237 youths. We examined the tool's internal consistency, content validity and structure validity. Analyses showed that all the subscales except democracy and influence had good internal consistency (0.70 and higher). However, inspection of individual items revealed that several items lacked clarity and many items did not comprehensively reflect the related constructs as intended. Confirmatory factor analysis suggested a poor fit for the proposed model (CFI = 0.52 TLI = 0.56, and RMSEA = 0.103). Currently, we are going through a second iterative process to increase the reliability and validity of Mina Svar. The work involves refining the framework, rewriting ambiguous items, generating new items, and re-examining the psychometric properties of the revised version.

Conclusions:
Mina Svar is a promising short multidimensional survey tool which offers a potential solution to tackle the problem with measuring the impact of social investments from the youth perspective.
statistics and Wilcoxon matched pair test used for comparisons. The significance level was set at p < 0.05.

Conclusions:
Results show that recommended surfaces derived from CADR declared by producers largely overestimate the real volume of the room that devices can purify, whatever the technology used.

Key messages:
There's no correspondence between recommended area of room to be sanitized indicated by producers of air purifiers and area that they are actually able to sanitize, which is significantly lower. It is necessary to be aware of the difference between data indicated by producers and real data, in order to purchase a device that actually corresponds to dimensional needs of the environment itself.

Conclusions:
Comparison between technologies analyzed by mean price normalized to CADR showed significant differences between those that used only UV lamps compared to all the others. This is reasonably due to the fact that the use of only UV lamps requires radiant powers considerably greater than all the others, therefore also higher costs (about 5-6 times). In all cases, the level of disinfection reached, as declared, was always > 95%. Key messages: With the same mean price normalized to CADR, the selling price is significanly different only for devices equipped with UV lamps compared to all the others. Choice of devices with a certain level of declared air purifications can be directed towards those with HEPA+UV/ HEPA/other without the mean price normalized to CADR undergoing significant differences.