UNC News Services
Breathing air containing coarse particulate matter such as road or construction dust may cause heart problems for asthma sufferers and other vulnerable populations, according to a new study led by the University of North Carolina at Chapel Hill School of Public Health.
The researchers found that in people with asthma, a small increase in coarse particulate matter in outdoor air raised bad cholesterol and increased the count of inflammation-linked white blood cells, among other changes.
The study, published in the May 2007 issue of Environmental Health Perspectives, was a collaboration by researchers from the School of Public Health, the School of Medicine’s Center for Environmental Medicine, Asthma and Lung Biology and the U.S. Environmental Protection Agency (EPA).
The team found that when adult asthma sufferers were exposed to a one microgram per cubic meter increase in coarse particulate matter in ambient air their triglyceride levels increased by nearly five percent. Elevated levels of triglycerides have been shown to increase one’s risk of coronary heart disease. The amount of eosinophils in study participants’ blood also increased by 0.16 percent after exposure to the higher levels of coarse particulate matter. Eosinophils are a type of white blood cell created by the human body to fight infections, allergies and diseases like asthma among other things.
Finally, the same increase in coarse particulate matter resulted in a three percent decrease in a measure of heart rate variability, the variation of the beat-to-beat intervals of the heart. A healthy heart has wide heart rate variability, while decreased variability can indicate stress or cardiac disease.
Study participants consisted of 12 adults between the ages of 21 and 50 with persistent asthma. All lived within a 30-mile radius of the study’s particulate matter monitor, located on the EPA Human Studies Facility at the Carolina campus. Each study participant took part in nine clinic visits: five the first week, and four spaced randomly over the subsequent six to 11 weeks.