Integrating portable air purifiers in German daycare centers during the COVID-19 pandemic – A qualitative exploration of usage, maintenance and impact on prevention behaviors

During the COVID-19 pandemic portable air purifiers with high-efficiency particulate air (HEPA) filters were suggested as a supplement to other prevention measures. Our previous study in German daycare centers did, however, not show a reduction in COVID-19 prevalence. The current study investigates possible reasons for the absence of preventive effects and examines confounding factors and particularities of the daycare setting. Prevention measures employed in the daycare centers, changes in prevention behavior as well as operation and maintenance of the purifiers were qualitatively assessed. The study follows an interventional design with the intervention group utilizing air purifiers. It was conducted in 29 daycares in three districts of the German federal state of Rhineland-Palatinate. Semi-structured qualitative interviews with the daycare heads were conducted between November 2022 and April 2023. The results show no major differences in prevention behavior between the intervention and control groups, thus inadequate prevention measures cannot explain the absence of the preventive effect of the air purifiers. The effectiveness of the air purifiers is more likely to be influenced by the type and duration of their use. Exploration of the usage behavior revealed inconsistencies in the frequency of usage, cleaning and maintenance, which are likely confounding factors. Further, thermal and acoustic emissions of the purifiers induced inadequate use. The findings indicate that the use of air purifiers must be compatible with the particular environment, otherwise the preventive effect is not realized. The daycare setting has not shown to be ideal for the adequate use of portable air purifiers. • Air purifiers did not impact other preventive measures in daycare centers. • Thermal and acoustic emissions of air purifiers induced inadequate use. • Air purifier usage behavior, cleaning and maintenance were insufficient. • The daycare environment is not ideal for the adequate use of portable air purifiers.