Seasonal Variability of Airborne Particulate Matter and Bacterial Concentrations in Colorado Homes

摘要

Aerosol measurements were collected at fifteen homes over the course of one year in Colorado (USA) to understand the temporal variability of indoor air particulate matter and bacterial concentrations and their relationship with home characteristics, inhabitant activities, and outdoor air particulate matter (PM). Indoor and outdoor PM 2.5 concentrations averaged (±st. dev.) 8.1 ± 8.1 μg/m 3 and 6.8 ± 4.5 μg/m 3 , respectively. Indoor PM 2.5 was statistically significantly higher during summer compared to spring and winter; outdoor PM 2.5 was significantly higher for summer compared to spring and fall. The PM 2.5 I/O ratio was 1.6 ± 2.4 averaged across all homes and seasons and was not statistically significantly different across the seasons. Average indoor PM 10 was 15.4 ± 18.3 μg/m 3 and was significantly higher during summer compared to all other seasons. Total suspended particulate bacterial biomass, as determined by qPCR, revealed very little seasonal differences across and within the homes. The qPCR I/O ratio was statistically different across seasons, with the highest I/O ratio in the spring and lowest in the summer. Using one-minute indoor PM 10 data and activity logs, it was observed that elevated particulate concentrations commonly occurred when inhabitants were cooking and during periods with elevated outdoor concentrations.