Regulation must focus on the regional impacts of air pollution

Current environmental regulations focus on the mass of pollutant particles, however, researchers from the University of Illinois are calling for regulation to focus more on the regional and health-relevant factors. 

The study found that measuring the mass concentrations of PM2.5 that are 2.5 micrometers in diameter or smaller – does not correspond well with current methods for classifying particle toxicity. 

Additionally, the researchers found that PM2.5 exposure may be just as hazardous in rural areas as in urban areas – this challenges a common misconception that air pollution is more toxic in urban areas than in rural areas.

To examine the influence of oxidative potential more closely, the researchers collected PM2.5 samples weekly in the summer and autumn of 2018 and in the winter and spring of 2019. They chose three urban localities: Chicago, Indianapolis, and St. Louis; a rural location in Bondville, Illinois; and a roadside location adjacent to an interstate highway in Champaign, Illinois.

Using an automated analytical technique developed in a previous study, the team analysed the sample composition, oxidative potential, and mass. They found that all locations shared similar levels of oxidative potential – but saw a poor correlation between oxidative potential and mass. That suggests that some of the lighter particles that make up PM2.5 contribute more to tissue damage than others.

The lead author of the study, Professor Vishal Verma said: ‘The EPA classification of PM2.5 accounts for particle diameter and mass, which are characteristics that are easy to measure. However, not all particles that make up PM2.5 contribute to health equally.

‘Most air pollution studies have shifted focus from particle mass to a property called cellular oxidative potential. Cellular oxidative potential describes the capability of the particles to generate reactive, oxygen-based chemicals that can lead to a variety of health problems in the cells of lung tissue.”

‘Our rural samples did have less mass than those in the urban settings, but the oxidative potential was equal to samples from urban settings. Additionally, the oxidative potential of the rural samples was higher in the summer than in the winter, suggesting that summertime agricultural activity can produce PM2.5 particles that are just as toxic as those from urban settings.’

The team hopes this study brings attention to these newly uncovered risks associated with PM2.5 in rural areas.