Emissions from Hydrogen Peroxide Disinfection and Their Interaction with Mask Surfaces.

A rise in the disinfection of spaces occurred as a result of the COVID-19 pandemic as well as an increase in people wearing facial coverings. Hydrogen peroxide was among the recommended disinfectants for use against the virus. Previous studies have investigated the emissions of hydrogen peroxide associated with the disinfection of spaces and masks; however, those studies did not focus on the emitted byproducts from these processes. Here, we simulate the disinfection of an indoor space with H2O2 while a person wearing a face mask is present in the space by using an environmental chamber with a thermal manikin wearing a face mask over its breathing zone. We injected hydrogen peroxide to disinfect the space and utilized a chemical ionization mass spectrometer (CIMS) to measure the primary disinfectant (H2O2) and a Vocus proton transfer reaction time-of-flight mass spectrometer (Vocus PTR-ToF-MS) to measure the byproducts from disinfection, comparing concentrations inside the chamber and behind the mask. Concentrations of the primary disinfectant and the byproducts inside the chamber and behind the mask remained elevated above background levels for 2-4 h after disinfection, indicating the possibility of extended exposure, especially when continuing to wear the mask. Overall, our results point toward the time-dependent impact of masks on concentrations of disinfectants and their byproducts and a need for regular mask change following exposure to high concentrations of chemical compounds.

Quantifying the impact of urban road traffic on air quality: activity pre-pandemic and during partial and full lockdowns.

The impact of partial and full COVID lockdowns in 2020 on vehicle miles traveled (VMT) in Kuwait was estimated using data extracted from the Directions API of Google Maps and a Python script running as a cronjob. This approach was validated by comparing the predictions based on the app to measuring traffic flows for 1 week across four road segments considered in this study. VMT during lockdown periods were compared to VMT for the same calendar weeks before the pandemic. NOx emissions were estimated based on VMT and were used to simulate the spatial patterns of NOx concentrations using an air quality model (AERMOD). Compared to pre-pandemic periods, VMT was reduced by up to 25.5% and 42.6% during the 2-week partial and full lockdown episodes, respectively. The largest reduction in the traffic flow rate occurred during the middle of these 2-week periods, when the traffic flow rate decreased by 35% and 49% during the partial and full lockdown periods, respectively. The AERMOD simulation results predicted a reduction in the average maximum concentration of emissions directly related to VMT across the region by up to 38%, with the maximum concentration shifting to less populous residential areas as a result of the lockdown.