A couple weeks ago there was an editorial in the Sunday newspaper that included a mention of "our deteriorating environment." It got my attention, but it's not the first time I have heard that. Sometimes when I give talks to schoolkids I ask them if they think the air has gotten cleaner, dirtier or stayed the same over the last 30 years. Most of them say "dirtier."

Before moving to the mid-valley in 1989, I lived in Southern California. I worked mostly in air quality studies, so I know a thing or two about air pollution. Most of my work involved working on environmental impact studies, required by the state and the federal government. Whenever a new factory, power plant, highway or other facility is planned, it must undergo an impact study to estimate how it will affect the air, the water, the biosphere and so on.

In the 1950s, '60s and '70s, Southern California's air quality was really bad. I lived about 100 miles from Los Angeles, and when I'd go there my eyes would burn and I'd have trouble breathing. I always felt kind of sick when I was there.

In 1970, Congress passed the Clean Air Act Extension. This mandated "ambient air quality standards" for various pollutants known to affect human health or damage property. Among the pollutants for which standards were established were ozone, sulfur dioxide and carbon monoxide.

Emission controls on vehicles and stationary sources followed soon after. As time has passed, the standards have become much tighter, so today's vehicles emit far less than they did before 1970. One prominent manufacturer claims that the exhaust from its car is cleaner than the ambient air in L.A.

And that's saying something, because L.A.'s air is getting much cleaner, despite increasing numbers of people and vehicles. In 1975, for instance, Los Angeles' one-hour ozone exceeded the standard in

192 days out of the year - more than half the time. But that number began to fall and continued to do so. By 2005 it was down to only 27 days.

And this trend actually understates the magnitude of improvement. Under EPA rules, a violation at just one (out of dozens) of ozone monitors in the large Los Angeles air basin is enough to qualify as a violation for the whole basin. Actually, there are large areas of the Los Angeles air basin where there have been no violations of the ozone standard for the last several years, which suggests that many residents have had no exposure to high levels of ozone.

Other pollutants have seen similar improvements: Carbon monoxide, particulates, nitrogen oxides, sulfur dioxide and lead have seen big declines in emissions. The air in L.A. is way better than it used to be! And as older, dirtier cars are taken out of circulation and replaced by newer, cleaner ones, this trend will continue.

But that's L.A. What about Oregon?

Same story. According to the Oregon Department of Environmental Quality, "In 1980, only 30 percent of Oregonians lived in clean air areas that met national health standards for air pollution. Today, all areas in Oregon meet these standards."

At the same time, the DEQ is addressing another group of pollutants, air toxics, that has emerged as a serious concern. Not much is known about these, so ambient air standards don't exist yet, but now that Oregon is fully in attainment of national air quality standards, the DEQ can concentrate on the other compounds. Doubtless it will.

George Taylor directs the Oregon Climate Service at Oregon State University. Send your weather questions to him at taylor@coas.oregonstate.edu.