Particulate matter (shown as PM 2.5 or PM10) and ground-level ozone (O3) — common pollutants —have been shown to rise when it’s hotter. Ed Avol is a professor emeritus of USC’s Keck School ...

But its accumulation at ground level can be very dangerous, Mongabay contributor Sean Mowbray explains in an article published in April. Ground-level, or tropospheric, ozone forms when methane ...

The windy weather whipping across Colorado on Monday morning brought unwelcome ozone from the upper atmosphere down to ground level, leading state air quality officials to issue a health advisory ...