Air pollution causes human disease and death. Regulators create air pollution policies to address this, even if they are expensive because they can quantify the monetary benefits of saving people from diseases. Still, as incredible as it may seem, we don’t know much about how cleaning up the air benefits wildlife. 

A new study takes a step towards understanding more about how air pollution affects birds. They used bird observations across the United States between 2002 and 2016 (from a community-based bird observation network), combined with independent estimates on bird population sizes and the US EPA’s pollution monitor readings. 

They used a statistical model to estimate changes in bird abundance over time. The results show that there is a strong negative association between bird abundance and ambient ozone concentrations in the United States. Additionally, the results show that the regulation aimed at reducing ozone precursors has significantly boosted populations in the eastern United States. 

This finding is not entirely surprising: high levels of ground-level ozone can damage the respiratory system of birds and also influence them into changing habitat conditions. What is surprising is that the results show no evidence for an association with particulate matter, a very harmful form of air pollution for humans. 

The natural next step should be quantifying the ultimate benefits that originate from the increase in the bird population. Ecosystem services provided by birds include pollination, seed dispersal, insect control, among others. Accounting these benefits in the cost-benefit analyses for air pollution regulation can help us design better policies and better allocate our limited resources.