An American study says carbon monoxide exposure has been found to elevate the risk of hospitalization for the elderly with heart problems.
The nationwide study of 126 urban communities has shown that an increase in carbon monoxide of 1 part per million in the maximum daily one-hour exposure is linked with a 0.96 percent increase in the risk of hospitalization from cardiovascular disease among people over the age of 65.
The connection remains even when carbon monoxide levels are less than 1 part per million, which is well below the Environmental Protection Agency's (EPA) National Ambient Air Quality Standard of 35 parts per million.
Presently, the EPA is evaluating the scientific evidence on the link between carbon monoxide and health to determine whether the health-based standard should be modified.
"This evidence indicates that exposure to current carbon monoxide levels may still pose a public health threat. Higher levels of carbon monoxide were associated with higher risk of hospitalizations for cardiovascular heart disease," said Michelle Bell, the study's lead investigator.
Working in collaboration with experts from the Johns Hopkins Bloomberg School of Public Health and the University of Southern California's Keck School of Medicine, Bell analyzed hospital records for 9.3 million Medicare recipients and data on air pollution levels and weather, gathered between 1999 and 2005.
The analysis considered the health effects of other traffic-related pollutants, including nitrogen dioxide, fine particles, and elemental carbon.
"We found a positive and statistically significant association between same-day carbon monoxide levels and an increased risk of hospitalization for cardiovascular disease in general, as well as for multiple, specific cardiovascular disease outcomes, including ischemic heart disease, heart rhythm disturbances, heart failure and cerebrovascular disease," said Bell.
Carbon monoxide is a tasteless, odorless gas that is a component of automobile exhaust.
The researchers stressed the need for additional research to investigate whether carbon monoxide or a combination of it and other traffic-related pollutants could result in increased cardiovascular hospitalizations in the elderly.
Their most recent findings have been detailed in a research article published in Circulation: Journal of the American Heart Association.