Particles in the Air: The Deadliest Pollutant is One You Breathe Every Day by Doug Brugge

Author:Doug Brugge
Language: eng
Format: epub, pdf
ISBN: 9783319895871
Publisher: Springer International Publishing

In fact, in drawing conclusions from epidemiology, replication across large numbers of studies with different designs and limitations as well as studying different populations are all important. There have been many studies of second hand smoke exposure and lung cancer as well as other disease outcomes. Sticking with lung cancer, a paper published in 2000 in the journal Lung Cancer [13], found 40 studies and pooled the findings to calculate a combined risk in what is known in the field as a meta-analysis [14].

Because there were two study designs that had been used, the meta-analysis calculated two combined risk estimates. One indicated an increased risk for lung cancer of about 20% and the other about 30%. The fact that a majority of the studies showed associations and that the combined estimate of effect from all the studies was positive and statistically significant supports the conclusion that the risk is real. I would add that this is also eminently plausible since tobacco smoke had already been shown to cause lung cancer in smokers and the chemicals in tobacco smoke are well established to be carcinogenic in animals. More recently a meta analysis of studies with low cigarette use found about a 50% increased risk from smoking just one cigarette per day, similar to what one might inhale from second hand smoke.

In the 1990s when I was testifying at local boards of health about the hazards of second hand smoke, I used calculations from a third Repace and Lowrey article as prime evidence of the futility of using ventilation and filtration to reduce second hand smoke levels in buildings [15]. In this article, they undertook calculations to assess how much ventilation would be needed to reduce cancer risk from cigarette smoking in a “typical” office. This was critical to me because the argument of the restaurant industry representatives was that smoking hazards could be controlled by better ventilation, which obviated the need to ban smoking.

In their paper the chemistry and physics duo used the risk that they calculated from the Seventh Day Adventist study (above) to calculate a level of PM that would result in an “acceptable” risk which, according to the US EPA, would be a risk of 1 lung cancer death in 100,000 people. They then ask how much ventilation would be needed to reduce the second hand PM in an office if one third of the workers in the office smoked. Obviously, there are a lot of assumptions that go into a calculation of this sort, but it is valuable for giving one a sense of order of magnitude.

Their answer was that you would need 226 air changes per hour to reduce the risk below the EPA guideline. In other words, the air in the office would have to be completely changed over 200 times every hour. That level of ventilation, or even anything close to it, is unimaginable from a design standpoint. It is completely impractable because of the need to heat or cool so much air and even just in terms of the sheer amount of airflow the office would experience.

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