PHOENIX -- The Arizona Department of Environmental Quality has issued an ozone health watch for Wednesday.
A health watch for ozone means pollution might approach the federal health standard. People who are extremely sensitive might be affected and should consider limiting outdoor activities or exertion.
A health watch is one step below a high pollution advisory or HPA, during which pollution might exceed the federal health standard.
"Active children, adults and people with lung disease such as asthma should reduce prolonged or heavy outdoor exertion," according to ADEQ.
"Ozone season" started in the Valley of the Sun on April 1, which is when temperatures start heating up, cooking an invisible gas emitted by vehicles, gas- and diesel-powered equipment and industrial activity. The season generally runs through the end of September, which is longer than most average cities.
Because ozone is colorless, there is no telltale layer of smog like we see with an inversion layer. That "brown cloud" is what most people associate with pollution advisories, but in the case of ozone, skies can appear perfectly clear.
While you can't see ozone, many people, particularly adults who have breathing issues and children, can feel it.
Ozone in the stratosphere is good. It protects the surface of the Earth by absorbing ultraviolet radiation from the sun. Ground-level ozone, however, is another story. High levels can be toxic to humans, animals and plants.
"Ozone is different than other pollution in that it is odorless and colorless but is just as dangerous to your health," Maricopa County Air Quality Director Bill Wiley said earlier this month.
“Recurrent exposure to high levels of ozone or particular matter can actually increase the chance of you developing lung injury, in other words you can have a decline in your lung function,” Dr. Rajeev Saggar with the St. Joseph’s Heart and Lung Institute said last summer.
Effects of prolonged exposure to high levels of ozone include throat and lung irritation. It also can exacerbate symptoms of asthma or emphysema.
With that in mind, many doctors suggest downgrading strenuous activity -- walking instead of jogging, for example -- and limiting time outdoors during the heat of the day whenever possible.
According to MCAQD, there are several easy things we all can do to reduce ozone.
- Refuel after dark
- Drive less; carpool when possible
- Avoid idling (i.e. in drive-thru lines)
- Use low-VOC paints (Volatile Organic Compounds); delay big projects when possible
- Conserve electricity