Effect of cigarette smoke on the lifetime of electret air filters

The role of air filters is becoming increasingly important due to the threat of air pollution to public health. Understanding the lifetime of air filters is essential for assessing air pollution exposure. However, the effects of common environmental chemicals on filter performance have not been explored. Air filters in ventilation systems and air purifiers are commonly exposed to cigarette smoke aerosols. Moreover, due to the coronavirus pandemic, people are more likely to be in close proximity with smokers while wearing face masks, such that their masks will be exposed to cigarette aerosols. In this study, we applied a stepwise approach to analyze the effects of cigarette smoke on the filtration performance of electret melt-blown filter media that are commonly used to create face masks. We found that cigarette aerosols dramatically reduced filtration efficiency, while standard test particles of a similar loading weight did not affect filtration efficiency. After loading up to 204 μg/cm² of cigarette smoke on 100 cm² of electret filter medium, the filtration efficiency of some filters decreased from 92.5% to 33.3% (-Δ59.2%). Interestingly, we founded no changes in pressure drop following cigarette smoke exposure despite the reduction in filtration efficiency, suggesting that cigarette smoke aerosols significantly impact the electrostatic charge properties of the filters. Our results indicate that the lifetime of commonly-used air filters may be much shorter than expected and that people may unknowingly be directly exposed to airborne pollutants.