With Air Quality Alert for Chicago area, remember that ozone is good up high, bad nearby
While you may think of ozone as a welcome element in our Earth's atmosphere that protects us from the sun's harmful radiation, ground-level ozone that we breathe is a harmful pollutant.
That's why ozone is good up high, but bad nearby.
The stratospheric ozone layer acts like a sunscreen for the planet, absorbing much of the sun's UV-B radiation. This radiation would otherwise damage our skin cells, increase skin cancer risk, harm our eyes, and affect plants and ecosystems.
But down at ground level, the ozone that we breathe is a lung-irritating pollutant. Breathing ozone pollution can trigger asthma symptoms and make it harder to breathe, especially for young children, older adults, and people with heart or lung disease.
Ground-level ozone (O₃) is an invisible, odorless molecule that forms through a chemical reaction. Pollution from cars, trucks, factories, gas-powered lawn equipment and other sources releases some of the necessary ingredients into the air. Add in direct sunshine, hot temperatures and light winds, and the sun "cooks" that pollution into ozone.
This is why Air Quality Alerts for high ozone levels often show up during hot, stagnant weather patterns like the one Chicagoland is in for Tuesday and Wednesday. The pollution generated by cars and industry sits overpopulated areas instead of blowing downwind and mixing out.
Ozone levels typically peak during the hottest part of the afternoon.
During an Air Quality Alert, the best action is to take it easy during the hottest part of the day. Limit strenuous outdoor activity so you are breathing fewer pollutants, shift exercise or yard work to the morning or later in the evening, and take extra care if you are in a sensitive respiratory group.
We can all also do our part to help cut down on the pollution that creates ozone. Carpooling, using public transit, avoiding unnecessary idling, and delaying refueling your vehicle until later in the day can all help reduce ozone buildup.
So remember: Good up high, bad nearby. Ozone protects us up high in the atmosphere, but on hot, sunny, stagnant days, it can become a problem right here at ground level.
