More PM2.5 Posed Risks to Taxi Drivers, Study Says

A study evaluating the relationship between exposure to fine particulate matter (PM2.5) and heart rate variability (HRV) in taxi drivers in Beijing, China before, during and after the 2008 Beijing Olympics has documented the health effects of the country's massive air clean-up effort prior to the Games.

The report is published online ahead of print in the peer-reviewed journal Environmental Health Perspectives.

Study participants were exposed to a wider range of PM2.5 pollution levels than participants in previous air pollution studies. Average PM2.5 levels during the Olympics were less than half the average exposure levels experienced by the drivers before and after the Games – but still were higher than those experienced by other study populations.

The results showed that increases in PM2.5 pollution levels were associated with decreases in HRV in young and healthy taxi drivers. Decreased HRV is a risk factor for adverse cardiac effects such as heart attacks.

"A major strength of this study is that we evaluated the same workers during three different time periods that had markedly different PM2.5 air pollution levels, which allowed us to compare the corresponding levels of 5-minute HRV indices among different time periods," wrote first author Shaowei Wu and colleagues. "A comparison of raw five-minute HRV indices indicated that the low PM2.5 exposure period (during the Olympic Games) was associated with relatively high HRV, while higher PM2.5 exposures (before and after the Olympic Games) were associated with relatively low HRV."

Other authors of the paper included Furong Deng, Jie Niu, Qinsheng Huang, Youcheng Liu and Xinbiao Guo. The study was supported by grants from the National Key Technologies R&D Program of China and the National Natural Science Foundation of China.

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