Mention air pollution and most people get visual images of industrial smokestacks spewing poison into the air.
But state environmental regulators say people should think smaller. Much smaller, as in the tailpipes of their own cars. Cars, not industry, are the biggest source of all major forms of Wasatch Front air pollution.During the hot summer days, cars along the Wasatch Front collectively produce 75.7 tons of organic chemicals, 74.1 tons of nitrogen oxide and 637 tons of carbon monoxide - a total of roughly 787 tons of air pollutants. And that amount is produced every single day, according to statistics provided by the Utah Division of Air Quality.
"You look at the numbers, and there is no way around the fact that cars are the biggest source of brown gunk you see in the air and the biggest source of what you can smell," said Dave McNeill, a division manager.
To make matters worse, especially during the dog days of summer, the chemicals produced by cars and trucks also combine in sunlight and heat to create dangerous ozone. On several occasions this summer, the state exceeded federal ozone standards, prompting state regulators to plead with the public not to drive their cars.
The experts warned folks not to exercise during hours when ozone is high, to refill their gasoline tanks only in the evening hours and to curtail use of lawn mowers and leaf blowers.
Believe it or not, this summer's air pollution problem is not the yucky brown haze hanging over the valley, although that certainly has the attention of those who monitor air quality.
Ozone is colorless and odorless, but it poses a huge health hazard. Remember what happens to rubber bands left in direct sunlight? Ozone does that same thing to human lungs.
"It destroys the lining in the lungs," McNeill said. "It breaks down the lung tissues and makes it crack just like elastic. It destroys tissues that are hard for the body to repair."
It is especially hard on the elderly, on children whose lungs are still developing and those who exercise (they breath deeper while exercising, damaging the lungs to a greater extent).
The ozone villain is cars, which produce three types of air pollution - hydrocarbons, nitrogen oxide and carbon monoxide - that combine to make ozone. In fact, cars produce several times the amount of all three pollutants as do industry or other sources.
There is no evidence that "no-drive" days actually impact the ozone level much. But that's not the point. Rather, the division is trying to raise public awareness of the problem and reduce ozone through the cumulative effects of an environmentally friendly ethic.
It may sound like a cliche, "but every little bit helps," said Ursula Trueman, director of the Division of Air Quality. "One car that stays home doesn't mean all that much. But when you have many small, individual steps, it can contribute significantly to better air quality."
Of all of the things people can do to alleviate the ozone problem, air quality officials say using mass transit is still the most effective.
According to McNeill's calculations, on a 100-degree summer day, a single car traveling at 35 mph will produce 1.91 grams of hydrocarbons (the brown haze you can see), 1.62 grams of nitrogen oxide and 12.95 grams of carbon monoxide for every mile it travels.
A diesel bus traveling the same speed on that same summer day will produce 3.13 grams of hydrocarbons, 9.03 grams of nitrogen oxide and 10.37 grams of carbon monoxide.
In other words, a Utah Transit Authority bus carrying 45 people - the equivalent of about 37 cars, according to Utah Department of Transportation estimates - produces less carbon monoxide than the one car idling next to it. It produces a little more than twice the amount of hydrocarbon and about five times the nitrogen oxide.
It's a case of simple math: One loaded UTA express bus from Ogden to Salt Lake City can take 50 cars off the road, maybe even more.
"People may be tired of hearing it, but mass transit does make a lot of sense from an air quality standpoint," McNeill said. "The fewer cars on the road, the less air pollution. It's easy to look out and see the air pollution and point the finger at industry or someone else when we should be looking at what we need to be doing ourselves."
Then again, the air pollution you don't see out your window in the morning could eventually kill you. Bus pass, anyone?
Pollution along the Wasatch Front per day
Car vs. bus comparision
Comparision is modeled on the vehicles traveling at 35 mph on a day with a temperature of 100 degrees F.
Pollution in grams: Car bus
Hydrocarbons 1.91 3.13
Nitrogen oxide 1.62 9.03
Carbon monoxide 12.95 10.37
NOTE: Bus becomes pollution effective when it carries at least 6 passengers.
Sources Organic chemicals Carbon monoxide nitrogen oxide
Pollution measured in tons
dry cleaning, misc.
(small sources) 40.8 4.9 *7.2
Cars and trucks 75.7 637.04 74.1
Industry 12.25 3.7 27.7
heavy equipment 33 292.7 50.4
Biogenics (natural decay) 38.9 0 0
*Includes forest fires and incinerators