A new long-term study evaluated how sources of fine particulate matter (PM2.5) have changed over the past two decades across 12 monitoring sites in five western U.S. states, including Utah, California, Nevada, Idaho, and Colorado. By combining advanced methods, Positive Matrix Factorization and Chemical Mass Balance, the study assessed contributions from multiple sources such as vehicle emissions, dust, biomass burning, and industrial pollutants.
The results show a clear impact of national and local air-quality regulations: concentrations of pollutants like secondary ammonium nitrate, sulfate, and vehicle-related elemental carbon significantly declined, even as vehicle miles traveled increased. Seasonal reductions in biomass-burning emissions were also observed, highlighting the effectiveness of residential wood-burning restrictions.
However, dust levels generally rose, likely due to increasing regional aridity and traffic. Overall, this study reinforces that consistent air-quality policies and targeted emission reductions have played a key role in improving air quality across the western U.S. over the last 20 years.
This research was supported in part by Kerry Kelly, co-founder of TELLUS.
Read the full article here: https://www.sciencedirect.com/science/article/pii/S1309104225003812?dgcid=coauthor
