Ozone and Your Health... Why You Should Spare the Air

By now, you’ve heard about the Spare the Air program. You’ve heard about those “Spare the Air” days on the news, or at your company. Maybe you’ve thought to yourself, “I know I’m supposed to Spare the Air, but can one person REALLY make a difference?” The answer is “YES!”

Ozone is bad for your health. We’re not talking about the “ozone layer,” which is more than ten miles above the earth’s surface in the stratosphere and protects us from ultraviolet rays. We’re talking about ground-level ozone, which is unhealthy to breathe. Ozone is created when oxides of nitrogen (NOx) and volatile organic compounds (VOCs) “cook” in the sun’s heat and light. This photochemical reaction, or “cooking” process, produces the most ozone during the long daylight hours of the summer months.

Where do NOx and VOCs come from? Mostly from motor vehicles. But they are also released from spray products (like hairsprays and oven cleaners), gasoline-powered lawn equipment, refueling your automobile, oil-based paints and varnishes, recreational boats, off-road vehicles, and charcoal lighter fluid.

Who is affected by Ozone?

You can’t really see or smell ozone, but you can feel it. Many people have experienced trouble breathing or chest pain when taking deep breaths on smoggy days. Those most affected with health problems when ozone concentrations are high are children, seniors and people with pre-existing respiratory illnesses like asthma or bronchitis.

The Bay Area’s “Hot Spots”

The Santa Clara, Livermore and San Ramon valleys can experience higher levels of smog than other parts of the Bay Area. This is due partly to geography. The coastal winds blow VOCs and NOx from the Bay Area’s morning commute into these valleys, where the afternoon sun “cooks” the pollutants. Ozone concentrations peak between 3 and 6 PM.

Preventive “Medicine”

The good news about ozone is that it can be prevented. The most effective thing you can do on a Spare the Air day, when we expect high pollution levels, is to leave your car at home. This can reduce up to a pound of emissions! This summer go to work without driving, by taking transit, carpooling, walking, biking or telecommuting. If you have to drive, minimize polluting “cold engine starts” by trip-linking — doing all your errands one after the other. And, refuel your car in the evening, when the VOCs are less likely to contribute to the smog problem.

Looking Back a Decade

This table summarizes the Bay Area's ozone experience going back to 1990.

*The 8-hour average national standard for ozone went into effect last year.  In 1999 there were nine days of new 8-hour standard excesses and three days of 1-hour standard excesses.