The South Coast Air Quality Management District (AQMD) has released a much-awaited draft report on its “MATES III” study. MATES stands for Multiple Air Toxics Exposure Study and, as the number indicates, it’s the third such study the agency has done. The studies estimate cancer risk for residents of the greater Los Angeles area caused by exposure to toxic air pollutants, which come from a variety of industrial and mobile sources.
Like MATES II, its predecessor, MATES III bases its findings on air quality measurements taken over one to two years at a combination of 10 fixed and five mobile monitoring sites around the region, including one in North Long Beach. MATES III finds that residents’ cancer risk from exposure to toxic air pollutants averages about 1,200 per million – compared with over 1,400 in a million found by MATES II, which was released in 2000. These risk values indicate the expected number of additional cancer cases in a population of one million people if they were exposed to these pollution levels over a 70-year lifetime.
The result for the North Long Beach site, located at 3648 N. Long Beach Blvd., was among the lowest in the study, though still high: a little over 900 in a million, less than the regional average. The highest risk value found by the study, just over 1,400 in a million, was in Fontana, where regional pollution tends to accumulate thanks to prevailing winds.
To put this risk in context, note that according to the American Cancer Society, “Half of all men and one third of all women in the United States will develop cancer during their lifetimes.” These risks arise from a combination of genetic, biological, behavioral, and environmental factors – in other words, things you are born with, things you do, and things you are exposed to, whether voluntarily or involuntarily. The AQMD’s finding that environmental exposure to toxic air pollution increases average cancer risk by 1,200 in a million means that, for a man living in Southern California, his risk of 1 in 2, or 0.5, is increased to 0.5012 (on average) by exposure to toxic air pollution. A small increase, to be sure, but an unwelcome increase nonetheless. For the Long Beach result of 900 in a million, the man’s total risk would be 0.5009.
Another significant finding of MATES II was that diesel exhaust was estimated to contribute 70% of the excess cancer risk. MATES III, using updated methods to determine diesel exhaust particulates, raises the estimate of this contribution to 84%. In summary, MATES III shows less risk overall than MATES II, but confirms the patterns showing that mobile sources – cars, vans, trucks – are responsible for a major part of cancer risk to residents of the LA basin.
To quote from the report, “While there has been improvement in air quality regarding air toxics, the risks are still unacceptable and are higher near sources of emissions such as ports and transportation corridors… The results from this study underscore that a continued focus on reduction of toxic emissions, particularly from diesel engines, is needed to reduce air toxics exposure.”
