From the Classroom: Ozone, Air Pollution, and the EPA

I've had this blog for nearly five years, and like many would-be bloggers, I've found my contributions become ever less frequent. This is largely a function of personal time, energy, and interest, but it also reflects the blog's lack of a clear identity. At first, I thought I'd write regularly about my travels and adventurers as a bicyclist. But while my enthusiasm for cycling hasn't waned, it has become much more narrowly channeled into my daily bike commute. While I've occasionally had reason to post about that commute here, there really is only so much one can say about the same stretch of road ridden day after day after day. If my bicycling adventures ever get more, umm, adventurous, then I'll be sure to post my tales here.

I have also posted here in the past some short pieces I've written originally for the students in one of my Geography classes at Santa Monica College. I've done this whenever I've written something that I thought might be of broader interest. Such is the case today, and I've decided to present it as the first of a new, occasional series on this blog I'm calling "From the Classroom".

Yesterday in my Introduction to Physical Geography class, I briefly covered the topic of air pollution. Following the lead of the really superb textbook I use in that class--Robert Chistopherson's Geosystems--I made a point to emphasize the profound progress made in the United States since the passage of the first Clean Air Act in 1970. As if on cue, today's New York Times included an article discussing proposed new air-pollution standards by the U.S. government. I shared a link to the article with my students, along with the following thoughts

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Note how today's debate continues to center around economic estimates: the billions of dollars it will cost government and industry to comply with the new standards and the billions of dollars--perhaps fewer, perhaps more--that society promises to save through improved public health. As a map accompanying the article shows, this is particularly significant for California (not just metro LA), where most of the counties already fail to meet current standards, making new stricter standards even more challenging and expensive to satisfy.

The new standards being proposed concern ozone. While this is the same three-oxygen-atom compound we discussed yesterday in class with respect to CFCs and the stratosphere, the ozone issue here is a different one. Up in the stratosphere, ozone is our "friend" as it protects us from UV radiation, and the concern is that human activity is causing a decrease in ozone, way up there. This air-pollution article, however, discusses ozone near the ground, at the bottom of the troposphere, where just the opposite situation is at play. Ozone down here is our "enemy", a harmful, unhealthful pollutant that human activity is causing to increase, hence the desire for government regulations to place an upper limit on its allowable concentration.

Ground-level ozone is one of the most significant components of "smog". It is formed in the atmosphere, especially on warm, sunny, calm days, which allow photochemical (i.e., sunlight-driven) reactions to create ozone out of various industrial emissions such as hydrocarbons and nitrogen oxides. Ozone is a major concern because it's a very powerful oxidant which works an awful lot like household bleach, killing living cells (including skin cells and those that line our lungs) on contact. As a former high-school cross-country runner who grew up in the "smog belt" of the Pomona Valley during the early 1980s, I can personally testify to just how painfully searing within one's chest outdoor exercise often could be back then. Sometimes I'm amazed that I can still breathe at all today, given the torture through which my coaches and I put my young body. The resilience of youth, I suppose.

Ozone similarly harms other living things in our environment, and can damage rubber and plastics as well. Through a chain of connections, this amplifies the full impact and cost of air pollution. For example, several decades of 20th-century air pollution have significantly contributed to the severe wildfire hazard in the mountains around Southern California. Always prone to fire, our forests today are even more so because they include large stands of dry, dying trees suffering from a major bark-beetle infestation. This may seem like an unfortunate "natural" event, but one of the reasons why the bark beetles have been able to thrive is that otherwise healthy trees were weakened by all the ozone pollution. (Drought and artificial fire suppression are additional significant factors.)

While continuing to sound the alarm about air pollution, we do also need to appreciate the phenomenal progress that we have already made. Yes, much of California continues to fall short of the current federal standard (ozone concentrations of no more than 0.075 parts per million), let alone the newly proposed stricter standards. But it's also worth mentioning how far we've come in the last few decades, despite the region's continuing economic and demographic growth. Within the Los Angeles basin, for example, there were 121 days in 1977 during which a "Stage 1 Smog Alert" was declared, which means local ozone levels on those days were greater than 0.20 PPM--nearly three times the current federal standard. Thanks largely to cleaner-burning automobiles, the number of Stage 1 alerts dropped to 66 in 1987, and to only 1 in all of 1997. There have been none since. We also haven't had a "Stage 2" alert (> 0.35 PPM) since 1988; that's a remarkable accomplishment. While getting a "smog check" done on your car can certainly be annoying, and it also adds to the expense of ownership and operation, keep in mind the benefits we enjoy every day through our radically improved air quality. One final set of numbers to share: an average 1965 Chevy Malibu emitted 8.8 grams of hydrocarbons and 3.6 grams of nitrogen oxides every mile; by 2003, a Chevy Malibu emitted only 0.6 and 0.1 grams of each. No wonder our air has gotten so much cleaner.

We still have some days in Southern California when the ozone levels are high enough to detect its distinctive "electrical" or "lightning-y" odor. It's an aroma that doesn't exactly bring back fond memories for me or many other Southern Californians who can remember the bad old days of the previous century.

FYI, in addition to the article in the New York Times, most of the numbers stated above I found through either the FDA's official website on ozone or another helpful one from the State of California.