Carbon monoxide increases health risk to elderly heart patients

WASHINGTON - Exposure to carbon monoxide (CO), even well below permissible national limits, may hasten hospitalisation of elderly cardiac patients, according to a new study in the US.

The nationwide study of 126 urban communities found that an increase in CO of one part per million (PPM) in the maximum daily hour-long exposure is linked with a 0.96 percent hike in hospitalisation risk from cardiovascular disease among people over 65 year.

This link holds true even when CO levels are less than one PPM, which is well below the National Ambient Air Quality Standard of 35 PPM in the US.

This finding suggests an under-recognised health risk to seniors. Currently, the Environmental Protection Agency (EPA) is evaluating the scientific evidence on the link between CO 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,” said Michelle Bell, the study’s lead investigator and associate professor of environmental health at the Yale School of Forestry & Environmental Studies.

“Higher levels of carbon monoxide were associated with higher risk of hospitalisation for cardiovascular heart disease.”

Bell and researchers from the Johns Hopkins Bloomberg School of Public Health and the University of Southern California’s Keck School of Medicine based their findings on an analysis of hospital records for 9.3 million Medicare recipients and data on air pollution levels and weather gathered between 1999 and 2005.

Their analysis took into account the health effects of other traffic-related pollutants, including nitrogen dioxide, fine particles and elemental carbon, said a Yale release.

These findings were published in Circulation: Journal of the American Heart Association.