If you want to give yourself a real heartache, spend about two hours in one of those glass-enclosed smoking areas at some of the nation's airports. Healthy nonsmoking volunteers working with researchers from Brigham Young University, Harvard University, and the University of Utah spent equal time in the smoky cubicle at Salt Lake International Airport and a smoke-free section of the airport [EHP 109:711-716]. The researchers measured the volunteers' heart rate variability--a marker of the health of the autonomic function of the heart--and found that sitting in the smoking chamber adversely affected this function of the heart.
"The most significant finding of our research is that we have observed that a relatively low concentration of tobacco smoke particles is associated with declines in heart function that may lead to adverse cardiac events," says lead researcher C. Arden Pope, III, a Brigham Young professor of economics who studies the impact of the environment on economic issues. Pope says the work may lead to the identification of the mechanistic pathways that allow particles from combustion to manifest as increased risk to the heart.
"To my knowledge," Pope says, "this is the first time we have been able to show that environmental tobacco smoke--[ETS, or] passive smoke--creates changes in heart rate variability." Pope says heart rate variability, the physiologic response of the heart to different activity levels, is well-described in the medical literature as a cardiac risk factor. Some researchers have suggested that failure of the heart to respond rapidly to changing circumstances bodes ill for long-term health, so reductions in heart rate variability caused by ETS exposure could prove detrimental (although this area is still controversial).
For many years scientists have seen an association between ETS and heart problems, but Pope and his colleagues saw that the physiologic pathways that turn ETS exposure into heart trouble had been left largely uncharted. In 1999 they set out to address this information gap. The researchers enrolled 16 adults aged 21-75. Nine men and seven women were divided into two eight-person panels. The subjects were hooked up to ambulatory heart monitors and sent into either the glass-enclosed smoking lounge at the airport or a nonsmoking area with a similar setting. Each panel completed two two-hour stints in both the smoking and nonsmoking areas. The participants would have been allowed to leave the test if they became ill or uncomfortable; however, all subjects completed the eight-hour length of the study.
The researchers monitored the blood oxygen concentrations of the subjects at regular intervals throughout the study. They also charted heart rate variability associated with standing, sitting, eating, and use of the bathroom. The subjects kept detailed activity diaries, which were used to rule out other possible activities involved in changes in heart rate.
The team found that during the smoking-lounge periods subjects experienced an average of a 12% decrement in the standard deviation of all normal-to-normal heartbeat intervals, which measures the time between specific points in a heartbeat and provides an estimate of overall heart rate variability. In other words, the subjects' heart rate variability diminished when they were being exposed to ETS. "This indicates a pathophysiological link between chronic environmental tobacco smoke exposure and cardiovascular health through the autonomic workings of the heart," Pope says.
Pope says this study correlates well with other studies showing that outside air pollutants have effects on the autonomic system. He also says that exactly what particles in smoke are responsible for the effect on the autonomic system requires further study.
|Printer friendly Cite/link Email Feedback|
|Publication:||Environmental Health Perspectives|
|Date:||Jul 1, 2001|
|Previous Article:||Funeral Wreaths.|
|Next Article:||Marine Swimming-Related Illness: Implications for Monitoring and Environmental Policy.|