It seems obvious that cleaner air is better, not only for the environment, but also for every person's health. Governments at the federal, state and local levels have regulated air polluters since the 1970s for this very reason. But remarkably, little empirical evidence exists to link government oversight of air pollution with medical outcomes.
A team of researchers at Hopkins' Bloomberg School of Public Health has just published an analysis of that relationship. Because epidemiologic studies have shown negative health effects due to exposure to pollution, the group set out to test the effect of pollution levels on mortality rates, or death rates, which are one of the most accessible measures of public health.
The researchers wanted to see whether current regulatory practices on pollution levels have actually been able to lower mortality rates. The group tested a specific type of air pollutant at different concentrations in order to understand the effects of higher and lower concentrations of a single pollutant.
The study consisted of testing the short-term effects of airborne particles, or particulate matter. Particulate matter, which includes contaminants like soot, is a common type of airborne pollution. Studying particulate matter allowed for analysis of a specific class of pollutant and the health effects arising from it.
The group used pollution data from the National Morbidity and Mortality Air Pollution Study, or NMMAPS. This data was broken down into geographical areas of different sizes, including counties, multi-state regions and the entire country. The purpose of this approach was to examine levels of pollution in all areas because levels of pollution can vary in different parts of the country.
The researchers compared each smaller region's pollution levels with the national average, which allowed for a more detailed and specific analysis of pollution patterns.
The pollution data was then compared with statistics showing the number of deaths from pollution-related diseases, to help determine a correlation between pollution levels and mortality counts. A variety of diseases can be caused entirely or in part by air pollution. These include a variety of lung diseases including certain lung tumors.
The results showed weak evidence that short-term effects declined due to lower levels of particulate matter at a low concentration. However at higher concentration of particulate matter, there was strong evidence that mortality rates declined as regulatory effects caused these levels to be lower.
These results can be used as evidence for the effectiveness of pollution regulations. As pollution regulations are difficult to enforce and can be costly, it is important to understand exactly which pollutant has the greatest effect on mortality rates.
This study has numerous implications for government regulators as well as polluters and public health professionals. It will help target regulations to areas of the country and types of pollution that are the most medically threatening. It will also help minimize spending money on air pollution regulation. Most importantly, however, this study provides hard evidence that will protect the health of citizens from toxic pollutants.
