A new study confirms that reducing ozone pollution could have prevented 1.5 billion bird deaths over the past 40 years. Today it is nearly 20% of the birds in the United States.

Our research shows that the benefits of environmental regulation have been underestimated. Reducing pollution has a positive effect on unexpected areas of life.

Ivan Rudik, Lead Author and Associate Professor, Cornell School of Applied Economics and Management
To study the relationship between bird numbers and air pollution, the researchers used data from the eBird birdwatching program and combined it with air pollution information at lower levels. They tracked monthly changes in bird numbers and air quality in 3,214 US counties over 15 years.

The team also drew attention to the US EPA’s NOx program, which aimed to protect human health by limiting ozone precursors’ emissions from major industrial sources.

The study results showed that ozone pollution is dangerous for humans and destructive for small migratory birds, for example, for sparrows and glints. They make up 86% of all land bird species in North America. Ozone pollution directly harms birds by damaging their respiratory system and indirectly by polluting their food sources.

Without regulatory requirements and measures to reduce the ozone layer, 1.5 billion more birds could die from pollution, the authors emphasize.