Ozone across northern hemisphere increased over past 20 years

In a first-ever study using ozone data from commercial aircraft, researchers found that levels of the pollutant in the lowest part of Earth’s atmosphere have increased across the Northern Hemisphere over the past 20 years. That’s even as tighter controls on emissions of ozone precursors have lowered ground-level ozone in some places, including North America and Europe.

Source: sciencedaily.com