Not All Air Pollution Harms Equally

Study Shows Larger Pollution Particles May Not Play Large Role in Hospital Admissions

Medically Reviewed by Louise Chang, MD on May 13, 2008
From the WebMD Archives

May 13, 2008 -- A new study shows that larger particles of air pollution aren't significantly linked to hospital admissions for heart or lung problems.

The goal of the study was to see how larger particulate-matter air pollution might play a role in hospital admissions for cardiovascular and lung disease. Researchers say that fine particles of air pollution have long been studied, but coarser ones have not.

Researchers pored over a database of Medicare billing claims from daily emergency hospital admissions from 1999 to 2005 and air pollution data from 108 counties across the U.S.

The results appear in the May 14 edition of The Journal of the American Medical Association.

All in all, there were nearly 4 million admissions for cardiovascular disease and almost 1.5 million admissions for respiratory disease looked at in the survey.

The people who were admitted with cardiovascular problems included those with diagnoses of heart failure, stroke, heart rhythm disturbances, and heart attack. Those who were admitted with respiratory problems included those with diagnoses of chronic obstructive pulmonary disease (COPD) and respiratory tract infections

Results of the study include:

  • Cardiovascular and lung disease rates were slightly higher in the eastern U.S. than in the West.
  • Respiratory disease rates were slightly higher in less urban counties.

In the western U.S. there was nearly double the level of coarse particulate matter air pollution (such as from mechanical grinding, agricultural activities, dust) than in the eastern U.S.

The study showed that breathing in coarse particles of air pollution was not significantly associated with emergency hospital admissions when it came to cardiovascular or lung disease.

Researchers say coarse particles can get stuck in the upper and larger airways.

Smaller particles in the air are mainly from vehicle exhaust or combustion. Studies have shown that when breathed deep into the lungs, these smaller particles reach the smaller airways and air sacs of the lungs. The researchers also note that the chemical makeup of particulate pollution can vary by size.

The U.S. Environmental Protection Agency uses these types of studies to set safety standards and regulations on air pollution.

The researchers urge further testing of larger particles.

Show Sources


Peng, R. The Journal of the American Medical Association, May 14, 2008; vol 299.

News release, The Journal of the American Medical Association.

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