Regulating killer particulate matter
March 1, 2010
Last Friday I again testified before the EPA on the health impacts of air quality. This time the subject was particulate matter. Once again, I was encouraging the EPA to follow through on a positive step it has proposed.
"Particulate matter" consists of extremely small airborne particles, generated primarily from coal combustion, oil combustion, and traffic. They’re distinguished by size as coarse particulates, with a diameter of 2.5-10 microns (PM10), and fine particulate, with a diameter less than 2.5 microns (PM 2.5). We’re talking extremely small. By way of comparison, a human hair is about 70 microns in diameter.
Back in 1997 the EPA proposed standards for PM 2.5 emission levels, and strengthened those standards in 2006. Unfortunately, EPA undermined its own rules by allowing coal and industrial plants to measure coarse particulates, or PM10, as a surrogate for PM 2.5.
They are now proposing to end those practices and return to a requirement to measure – and limit – PM 2.5.
That’s a very important thing to do. The health impacts of PM 2.5 are much greater than the impacts of PM 10, due to differences in the ways and the extent to which the smaller 2.5 particles penetrate the human body.
Small particles of particulate matter travel deep into the lungs, reaching the alveoli, the tiny air bags in the lungs whose thin walls allow oxygen to enter the blood. There, the particles that are 2.5 microns or less in diameter can pass through the alveoli walls and travel through the blood stream to other organs. As a result, not only the respiratory system but also the cardiovascular system and the neurological system are exposed to damage.
And it does cause damage! Among PM 2.5's impacts on the human body are:
- PM 2.5 can stunt lung development, leading to reduced lung function in children. This reduction of function often precedes the subsequent development of other pulmonary diseases.
- Exposure to PM 2.5 is associated with the exacerbation of Chronic Obstructive Pulmonary Disease, the fourth leading cause of mortality in the U.S.
- Exposure to PM 2.5 is also correlated with the development of and mortality from lung cancer.
- Higher ambient levels of PM 2.5 have been correlated with increased hospital admission rates for cerebrovascular disease, or stroke.
- Higher ambient levels of PM 2.5 increase the probability of hospital admission for acute myocardial infarction (heart attack), ischemic heart diseases, congestive heart failure, and potentially fatal cardiac rhythm disturbances.
Sometimes the increases in the rates of increased incidence appear small, on the order of a single percent. But when you consider the large number of cases of heart disease, even a small percentage uptick translates into a very large effect when measured in terms of total hospital admissions, patient morbidity and mortality, and the cost of health care, time lost from school and work, and simple human suffering.
In short, the danger to health posed by PM 2.5 is widespread, severe, and costly. I was glad to get the opportunity to tell that to the EPA.
If you agree that the EPA, to protect human health, should end the PM 10 “surrogate” policy and regulate PM 2.5, please post your comments online. You have until March 15.
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