The U.S. Environmental Protection Agency today released a new standard for ground-level ozone. The standard, 70 parts per billion, replaces the previous standard of 75 parts per billion.
So what does this mean?
Isn’t ozone supposed to protect us from the sun’s harmful radiation? If so why are they making the standard lower?
Ozone is a compound formed when chemicals emitted from vehicles, businesses, and industries react with sunlight. Therefore, summer tends to be “ozone season.” Ozone can have good or bad effects, depending on where it's located in the atmosphere. In the upper atmosphere, it provides a protective layer around the earth, absorbing ultraviolet radiation and preventing too much of it from reaching the ground.
But down where we live and breathe, ozone is a different matter — “good up high, bad nearby.” Down here, we also know it as smog. Ground-level ozone can cause chest pain, coughing, and throat irritation. It can worsen bronchitis, emphysema, and asthma. It can inflame the linings of the lungs, an effect that’s been likened to getting a sunburn in the lungs. Even small amounts in the air can have harmful effects.
So do we meet the new standard?
Yes. All areas of Minnesota currently meet the new standard. Some areas of the state are close to it, so we will be continuing to work to reduce ozone levels in Minnesota.
Who should care about all this?
Well, since we know that ground-level ozone can cause harm even at low levels, having less ozone in the air will be good for everyone. But like most air pollutants, ozone has more impact on sensitive populations — the very young, the elderly, people who exercise or work outdoors. These are the groups that will benefit most. On days when ozone levels reach unhealthy levels, the MPCA calls air quality alerts to let these populations know they might want to take precautions. You can find out more, and sign up for alerts, on MPCA's Current air quality index webpage.