In addition, people living in the smoggiest areas also had higher systolic blood pressure, and it didn't matter whether they were obese or of normal weight. However, the effect was greater among the obese, Kannan's team noted.
The researchers believe that individuals and society need to address the combined health threat of obesity and air pollution.
"Continued vigilance regarding regulation of emissions sources in communities of color and low-income communities is critical, combined with efforts to address obesity, in order to reduce well-established disparities in cardiovascular health," the researchers concluded.
Michael Jerrett, an associate professor of environmental health sciences at the School of Public Health of the University of California at Berkeley, said the study "is linking into the broader debates about underlying causes of death in our society."
For people who already have high blood pressure, diabetes or who are obese, air pollution may make these conditions worse, Jerrett said.
"You end up with this vicious cycle where someone becomes obese due to lifestyle and other factors, which actually becomes worsened by the air pollution," he said.
Jerrett noted that air pollution is only one environmental factor that contributes to worsening health. In addition, the poor are often exposed to more air pollution because of the neighborhoods they live in, he added.
"What comes along with the social deprivation is a cascade of other lifestyle and occupational factors that may also make the person more susceptible to air pollution's effects," he said.
Those factors can include poor nutrition, stress, traffic and industrial noise, Jerrett explained. "These can be heightening their sensitivity
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