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BLOG: April 2008

Smog, health, and politics

Just about a century ago, in 1905, a new word - smog - was coined from "smoky fog", describing the phenomenon characteristic of big cities in Britain, particularly London. Back then, little was known about the relation between smog and health. Despite plenty of research on the subject, what has been learned so far had very hard time to reach the public and - more importantly - to be used in establishing federal and state air-pollution standards.

Wouldn't you think that inhaling smog is not good for your health? Doesn't look like there is much to think about. Not only that it contains ozone (O3), potent irritant damaging lung tissue, but also particulate matter carrying unknown number of toxins, carbon monoxide, nitrogen dioxide and other toxic gases, smoke and dust. Quite a cocktail, but neither pleasing nor healthful. Amid mounting evidence of harmful effects of ozone on human health, Environmental Protection Agency (EPA) requested National Research Council (NRC) report on the subject.

The result of this brand new NRC report, made public this month, isn't much of a news: it confirms that there is a solid evidence - or, in their own words, "robust statistical evidence of an association" - of short-term ozone exposure - which was the focus of the report - and premature deaths. The conclusion is based on recent studies and research papers.

What is scary, is that the report only considers short term - less than 24 hours - ozone exposure, and deaths immediately following the exposure. Consequences of longer exposures, and long-term effect on health, are yet to be officially established. Also, while deadly effect of ozone cannot be efficiently separated from those of other toxic agents contained in smog, they have not been specifically addressed in the analysis.

In all, things are likely much worse than what the report indicates. While, according to the report, majority of the victims are those most vulnerable, with increased susceptibility to ozone, the susceptibility may not be obvious, or previously known. Even healthy individuals may suffer consequences.

For instance, those exercising are taking in up to 20 times the volume of air of a sedentary person, and by so much increase their effective exposure. Also, the effects of longer exposure on long-term health and life expectancy of the next most vulnerable group - children, who inhale up to several times more air than adults, in proportion to their body mass - have not been evaluated.

Evidently, the NRC report is very limited in its scope, but its results are insomuch more alarming.

Not everyone agrees with it, though, and among those is the White House Office of Management and Budget. Bush administration is downplaying the air pollution threat, trying to spare industry from expenses that would be triggered by more strict air quality standards.

Granted, it would be very difficult to actually enforce better air quality standards, considering that the majority of air pollution is created by mobile sources: trucks, trains, buses, automobiles, planes and ships. They produce precursors of ground-level ozone, organic compounds and nitrogen oxide (NO), with power-plants being major contributor to the NO emission. Ground-level ozone is produced through multitude of chemical reactions initiated by these precursors and magnified in particular by intense sunlight.

But the fact is - there is

no alternative to protecting health of the population.

The cost of illness, sick days, shortened lifespan and lower overall productivity are to be taken into consideration when considering the cost of reducing ozone precursor emission. Ground ozone concentration has increased from 10 ppb (parts-per-billion) in pre-industrial era to nearly 150-200 ppb in today's large urban areas, like Houston and Los Angeles. But this is still better than concentrations in excess of 400 ppb recorded back in the 1970s - it proves that significant improvement in air quality is possible when the determination exists.

For comparison, current categorization of air quality with respect to ozone concentration is "good" below 64 ppb, "moderate" 65-84 ppb, "unhealthy for sensitive" 85-104 ppb, "unhealthy" 105-124 ppb and "very unhealthy" over 125 ppb.

Interestingly, while the NRC report specifically attempted to establish threshold to ozone concentration below which the exposure would pose no risk of death, it was unable to come up with such.