TORONTO -- Air pollution regulations imposed to protect humans have had a positive effect on another species.

A recent study shows that around 1.5 billion birds were saved in the U.S. over the last 40 years as a result of ozone pollution laws issued to help safeguard humans from dirty air.

To figure this out, scientists analyzed data from an online database called eBird. The database allows users to log birds they see as well as the location, date and time of the sighting.

Researchers were able to track monthly changes in bird abundance, air quality, and regulation status in more than 3,000 U.S. counties over a span of 15 years using this data. The team then compared their findings to pollution rates in other places.

In the video at the top of this article, CTV News Science and Technology Specialist Dan Riskin explains why there is a correlation between air pollution and bird populations.