A study that might have you paying more attention to the quality of the air you breathe appears in The New England Journal of Medicine. It covers ozone danger in terms of over exposure.
The work showed that long-term exposure to ground level ozone significantly increases the risk of death from breathing problems. In fact, the risk is more than 30% greater in metro areas with the highest ozone concentrations as opposed to places where concentrations were lowest.
Ozone is a naturally occurring gas typically at the higher levels of our atmosphere where it offers protection from the ultraviolet rays of the sun.
But this gas can also be found at lower levels of the atmosphere; only down here it does us little good.
Produced by the exhaust from cars and power plants, at ground level ozone reacts chemically with sunlight. We know that the Environmental Protection Agency (EPA) says that ground level ozone can make lung conditions worse and contribute to other breathing problems as well.
The other, more well studied part of smog - particulate matter (super small particles of dust and soot) - has been shown in earlier research to be dangerous. Breathing in these particles has been identified as a major risk factor of death from both heart and lung diseases.
Only now do we know that ozone also brings a higher risk of death from these conditions.
The work followed 450,000 subjects in 96 metropolitan regions over an 18-year period. Despite what we might expect, ozone actually forms in higher concentrations in places that are downwind of the cities, so suburbs and rural areas aren't free of the danger, though they might be less congested and seem safer.
"This is the first study to show that ozone, long considered a secondary pollutant, is a key cause of death," says study lead author Michael Jerrett, Ph.D., an associate professor of environmental health at the University of California. "This is the first time we've been able to connect chronic exposure to ozone with the risk of death."
The risk of dying from a respiratory condition goes up 4% for every 10 parts per billion increase in ozone exposure according to the study.
During the 18-year period, Riverside California had the highest daily average concentrations, while the lowest were recorded in San Francisco.
Most often, cities in the northeast part of the country had less ozone than western states like California - Los Angeles had a 43% greater risk, while New York came in at 25%; Washington, D.C. at 27%.
What the experts recommend you do to manage your risk is to exercise or do physically demanding work in the early morning hours, or later on in the day to avoid the sunniest, hottest hours, especially if you live in a warmer climate.
Keeping your windows closed when ozone levels are highest is also a good idea, and you might want to limit your time spent outside when ozone levels are reported to be high.
On a larger scale, the researchers recommend steps be taken to reduce traffic congestion - maybe give financial incentives to carpoolers, set up more high occupancy lanes and encourage hybrid cars.
Higher gas taxes are a punishment often used to discourage excess driving, so there will be fewer vehicles on the road. Of course, power plants must also be dealt with, and regulations put in place to keep them from sending toxic chemicals into the air.
If you or someone you love has breathing problems, you might consider keeping an eye on the ozone levels with some of the easy to use online resources out there.
This will help you make wise choices and perhaps limit your ozone danger to a gas that researchers are finding increasingly dangerous.
