Ozone regulations benefit birds

An environmental regulation aimed at reducing human exposure to ozone pollution may also protect birds in the US, according to a new study led by environmental economist Catherine Kling at Cornell University. Her team analyzed 15 years of ozone-monitoring data from the US Environmental Protection Agency alongside citizen scientist bird observations in the continental US from the same time period. The researchers found that counties with higher levels of ambient ozone have less abundant bird populations (Proc. Natl. Acad. Sci. U.S.A. 2020, DOI: 10.1073/pnas.2013568117). That’s probably because ozone causes respiratory problems in birds and damages the plants they rely on for food and habitat, study author Ivan Rudik says. The team also found that counties in the eastern US that are part of the EPA’s NO_x Budget Trading Program, which was instituted to reduce summertime emissions of the ozone precursor nitrous oxides, have more robust populations of small land-based birds, such as those that frequent backyard feeders. These results suggest that current policy evaluations most likely underestimate the cobenefits of air quality regulations for wildlife, which could have “direct and immediate consequences for how we think about doing regulatory analysis through the EPA and elsewhere,” Kling says.