ABSTRACT
Due to the global response to the COVID-19 pandemic, there have been a variety of policy responses that have produced a range of expected and unexpected effects on society and our surrounding environment. One widely reported result of the pandemic response is that travel restrictions have resulted in improvements in regional air quality. This study aims to determine the effect of COVID-19 related Stay at Home precautions on air quality in a metropolitan area. We specifically focus on CO, NO2, and PM10 in Maricopa County (Phoenix), Arizona, as these all contribute to local air quality concerns. The role of meteorological parameters on ambient concentrations for these pollutants was investigated by using the local planetary boundary layer height (PBH) to account for vertical mixing. Across all three sites studied, there was no uniform decrease in either CO or NO2, even when freeway traffic volume was down by ~35%. For PM10, there was a significant decrease of ~45% seen at all the sites for the period most directly impacted by local Stay at Home restrictions compared to the past two years. This indicates that different pollutants have fundamentally different behavior in the local environment and suggests that these pollutants originate from different sources.
ABSTRACT
The COVID-19 pandemic is increasing the need for personal protective equipment (PPE) worldwide, including the demand for facial mask used by healthcare workers. Disinfecting and reusing these masks may off benefits in the short term to meet urgent demand. Germicidal ultraviolet light provides a nonchemical, easily deployable technology capable of achieving inactivation of H1N1 virus on masks. Working with N95-rated masks and nonrated surgical masks, we demonstrated that neither 254 nor 265 nm UV-C irradiation at 1 and 10 J/cm(2) had adverse effects on the masks' ability to remove aerosolized virus-sized particles. Additional testing showed no change in polymer structure, morphology, or surface hydrophobicity for multiple layers in the masks and no change in pressure drop or tensile strength of the mask materials. Results were similar when applying 254 nm low-pressure UV lamps and 265 nm light-emitting diodes. On the basis of the input from healthcare workers and our findings, a treatment system and operational manual were prepared to enable treatment and reuse of N95 facial masks. Knowledge gained during this study can inform techno-economic analyses for treating and reusing masks or lifecycle assessments of options to reduce the enormous waste production of single-use PPE used in the healthcare system, especially during pandemics.