Ten minutes of passive smoke affects heart

[Posted: Fri 17/04/2009 by Joanne McCarthy]

Exposure to small doses of secondhand smoke for as little as 10 minutes affects people’s cardiovascular function, a new study has indicated.

Secondhand tobacco smoke, smoke from cooking oil, and wood smoke were all found to affect the heart in both men and women, leading researchers to believe that damage to public health caused by smoking may have been underestimated.

The study also found that cardiac responses during brief exposures to smoke were similar to those found during longer or higher level exposures.

According to the researchers, evidence indicates that an increase in air pollution is associated with an increase in heart attacks and deaths. These pollutants, including tobacco and cooking oil smoke, contain fine particles that evoke responses from heart and blood vessels, indicating effects on their function.

The study briefly exposed participants to low levels of common pollutants and measured their responses. After the air was cleared, researchers measured respiratory and cardiovascular function, including heart rate variability, breathing and blood pressure. These measures gave researchers a picture of how the heart, circulatory and respiratory systems were reacting to the pollutants.

The study found that, particularly among men, exposure to smoke changed breathing patterns, raised blood pressure and shifted control of heart rate toward what is termed ‘sympathetic domination’. The sympathetic nervous system becomes active during times of stress, but can cause harm to the heart and blood vessels if activated too often or too long, as can occur when it is exposed to smoke.

These results confirm results from earlier studies, but with exposures that were at lower levels and for shorter lengths of time. The study also extended the findings in several ways, including finding that men and women respond differently.

“I was surprised we got statistically significant results with this low level of exposure. If we can detect these effects with smaller exposures, then the public health hazard from cigarettes and other exposures may have been underestimated,” said Joyce McClendon Evans of the University of Kentucky, who conducted the study.

The findings will be presented during the 122nd annual meeting of the American Physiological Society in New Orleans.