Air Pollution Linked to Increase in Hypertension Risk Interview with:
Tao Liu Ph.D
Guangdong Provincial Institute of Public Health
Guangdong Provincial Center for Disease Control and Prevention What is the background for this study? What are the main findings?

Response: Hypertension is the most important cause of disability and the leading risk factor for death globally and causes approximately 16.5% of all deaths. Since the 1990s, many epidemiological studies have investigated the associations between air pollution exposure and hypertension, the two most common public health concerns. However, their results remain controversial. Some studies found an association between them, while other studies sowed either no association or an association only for selected pollutants. In order to quantitatively synthesize and interpret these inconsistent and controversial results, here we used a new analysis method (Meta-analysis) to combine results from different previous studies to estimate the overall effect of every air pollutant on hypertension. This is the first study to simultaneously estimate the effects of short-term and long-term exposure to air pollutants on hypertension by meta-analysis. These results could provide more explicit information for policy decisions and clinical use. What are the main findings?

Response: We mainly found that air pollutants had both short-term and long-term effects on hypertension risks. For example, every 10μg/m3 increment in the ambient SO2, PM2.5 and PM10 concentration might increase the hypertension risk at the population level by 4.6%, 6.9% and 2.4% in the next several days (short-term effects), respectively. That means more emergency hospital visits for hypertension were found after the increase of air pollutants. On the other hand, each 10μg/m3 increment in long-term exposure (1-2 years) to NO2 and PM10 might chronically increase the hypertension incidence by 3.4% and 5.4%, respectively, which indicated that people who lived in an area with higher air pollution level will have higher risks of developing hypertension. What should readers take away from your report?

Response: Firstly, we aimed to let the policy makers or stakeholders know that air pollution could increase hypertension risk in a long-term exposure, and also even very short-term exposure can aggravate their conditions of hypertension. Therefore, it is urgent to take more actions to protect our environment and clean the air, because nobody could totally avoid air pollution due to the ubiquitous nature of air pollution. Secondly, we further want to let ordinary people understand our results: air pollution could increase their risks of developing hypertension. Everyone should take actions to decrease the air pollution. On the other hand, they could take measures to protect themselves from the adverse effects of air pollution: ①closely focus on the air quality every day, and try to avoid outdoor activities when air quality is poor;②put on masks when go outside when the air quality is worse; ③clean the indoor air to avoid these air pollutants, such as using air cleaner. What recommendations do you have for future research as a result of this study?

Response: Although we clarified the association between air pollution and hypertension risks, more research is needed. Firstly, due to the limited number of studies, the association between hypertension risks and some other air pollutants are still unclear, such as O3 and CO. Therefore, more studies are urgently needed. Secondly, we found that particulate matters (PM) are the major air pollutants affecting hypertension. However, it is well known that the components of particulate matters are complex, and different components come from different sources. Therefore, assessing the independent effects of each components in the particulate matters could provide more information for policy making to control the sources with the largest effects in priority. However, the current information on the effects of PM components are very poor. Thirdly, how to protect people from the adverse effects of air pollution remain unclear. For example, how about the effectiveness of mask and air cleaner to protect people from air pollution. Is there anything else you would like to add?

Response: Our current study mainly focused on the effects of air pollution on hypertension risk in ordinary people. However, it is suggested that children and the elderly are more sensitive to air pollution. Therefore, more attentions should be paid to these vulnerable groups. Thank you for your contribution to the community.


Yuanyuan Cai, Bo Zhang, Weixia Ke, Baixiang Feng, Hualiang Lin, Jianpeng Xiao, Weilin Zeng, Xing Li, Jun Tao, Zuyao Yang, Wenjun Ma, and Tao Liu. Associations of Short-Term and Long-Term Exposure to Ambient Air Pollutants With Hypertension: A Systematic Review and Meta-Analysis. Hypertension: Journal of the American Heart Association, May 2016 DOI: 10.1161/HYPERTENSIONAHA.116.07218

Note: Content is Not intended as medical advice. Please consult your health care provider regarding your specific medical condition and questions.

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Last Updated on June 1, 2016 by Marie Benz MD FAAD