The Smoking Habit You Didn't Know You Had
For many who are trying to take good care of their health, a study released late last week reaffirming that diesel exhaust can cause lung cancer, may be a major blow to their efforts to lead a healthy lifestyle. That’s because the study found an up to seven fold elevated risk of lung cancer - a disease typically associated with smokers - among miners who don’t smoke. The findings also relate to ordinary people who live in areas with high levels of diesel particulate matter (PM). Millions of people in the US have the equivalent of a smoking habit, whether they want to or not, because they live close to busy freeways or in other areas with extremely high diesel PM levels.
Scores of studies have shown that diesel exhaust, a sooty mix of toxic air pollutants, smog forming gases and tiny particulates, is dangerous. It was recognized by the State of California as a carcinogen over a decade ago, and fortunately many laws and programs are in place to reduce diesel pollution. However, even in California where there is a whole suite of diesel clean-up measures from low sulfur diesel fuel to retrofits and early retirements for trucks and equipment, thousands of people continue to die from exposure to diesel PM each year while these measures phase in over the next few decades. Diesel engines are sturdy, lasting decades with older models polluting a hundred-fold more particulate pollution than modern replacements.
The study by the National Cancer Institute and the National Institute for Occupational Safety and Health (NIOSH) evaluates diesel exposures and lung cancer risks among more than 12,000 miners and provides a rigorous analysis, adding weight to the already large vault of evidence that exposure to diesel PM can cause cancer. No wonder a lobby group representing mining interests worked so hard to delay and obstruct the findings of the study since 1996. The study finds that among heavily exposed miners who typically work underground, the risk of dying from lung cancer was roughly three times greater than for other miners working on the surface. That risk jumps to a seven fold increase of lung cancer for miners who do not smoke. The findings are consistent with previous large studies of truck drivers and rail workers that have found nearly a doubling of lung cancer risk among long-term workers in these relatively high diesel exposure occupations.
In addition to concern for the many workers who are exposed to high levels of diesel exhaust, the miners’ study shows that urban populations, as well as those living in close proximity to major diesel emissions sources - like freeways, rail yards, and ports - may face significantly elevated risks for lung cancer. There is a strong and consistent relation between exposure to diesel exhaust and increased risk of dying of lung cancer- the higher and longer the exposure to diesel PM, the greater the cancer risk. Environmental exposure to average diesel PM levels found in many large cities like Los Angeles and New York City over a lifetime approximates the cumulative exposures experienced by the “low exposure” miners group, which had a fifty percent increased lung cancer risk in the miners’ study.
High diesel PM exposures close the gap between lung cancer risks among smokers and non-smokers. Among workers in the lowest diesel exposure group of the miners’ study, heavy smokers of at least two packs per day had a risk of lung cancer 27 times that of nonsmokers (after 15 years), whereas heavy smokers in the highest mining exposure group had only 2.5 times the risk of nonsmokers (after 15 years).
So for those who live in areas with high diesel pollution levels, how do they quit the smoking habit that they didn’t choose to have? It will take an investment in clean, new diesel equipment and retirement of old smoking vehicles. Tell policymakers that you want the diesel vehicles around you to quit smoking.