Analysis of indoor and outdoor PM2.5, NOx, black carbon (BC), SO2, O3, CO and BTEX in a street canyon in the colder months

Abstract

This study focused on collection of pollution data in an urban street canyon in Gżira, Malta and in an indoor office environment. Data was collected during February and March 2023. Data was collected regarding PM2.5, SO2, O3, NOx (NO and NO2), BC and CO. During the indoor sampling campaign, the air exchange rate (AER ) was altered once, by keeping the only window in the room slightly open for part of the sampling campaign and closed for the other part. Analysing indoor air quality (IAQ) has become of increased interest, due to the time humans spent indoors and the many health risks with poor air quality, included increased morbidity and mortality. From this it was shown that as the AER increased, the boundary between indoor and outdoor was breached and the indoor environment with an unsealed window is more like the outdoor environment. The levels of regulated pollutants were also compared with concurrent data provided by the Environmental Resource Agency (ERA) from different sites in the Maltese Islands. The levels in the street canyon were noticeably higher than other locations. This indicates that the canyon effects may have played a role in increasing the concentration of pollutants.