Exposure to PM 2.5 heightens risk of high blood pressure, hypertension: Study2 min read . Updated: 30 Aug 2020, 06:32 PM IST
- The study was carried out in a cohort of 5,300 individuals recruited across different parts of Delhi and followed for seven years (2010-2016) with annual questionnaire surveys and alternate year biological sample collection
NEW DELHI: Exposure to PM2.5, particulate matter that has a diameter less than 2.5 micrometres (more than 100 times thinner than a human hair) and remain suspended for longer, can have strong effects on systolic and diastolic blood pressure (BP) and increases the risk of developing hypertension, shows a study published in the Journal of the American Heart Association.
The study conducted by Indian scientists at the Centre for Chronic Disease Control (CCDC) and Public Health Foundation of India (PHFI), in collaboration with the Harvard T.H. Chan School of Public Health, investigated the association between exposure to ambient PM2.5 with blood pressure and incident hypertension in subjects from Delhi.
The scientists found a higher average of systolic BP —1.8 mm Hg and 3.3 mm Hg— in monthly and annual exposures. Positive but less pronounced associations were also observed for diastolic blood pressure. The study found that average PM2.5 exposure over 1 year, 1.5 years and 2 years increased the risk of developing hypertension by 50%, 60% and 20%, respectively. The results were stronger in participants with higher waist-to-hip ratios, an indicator of central obesity.
The study was carried out in a cohort of 5,300 individuals from across Delhi, who were followed for seven years between 2010 and 2016, with annual questionnaire surveys and biological sample collections every alternate year.
The major sources of PM2.5 in Delhi include traffic, power plants, and industries, besides agricultural crop burning in neighbouring states. The paper assessed daily ambient PM2.5 using a machine learning-based predictive model, which included myriad data sources, including ground monitor data from the Central Pollution Control Board and Delhi Pollution Control Committee, satellite observations, meteorology, land use variables and emission inventories. Blood pressure was assessed longitudinally at three time points within the cohort over the seven-year period.
“In India, there is very little or no evidence linking the exposure of ambient PM2.5 as a marker of air pollution with hypertension," said Prabhakaran, vice-president, research and policy, PHFI; executive director, CCDC, and lead investigator of the study.
“The findings show both short- and long–term exposure to air pollution contributed to higher BP and increased risk of hypertension especially in certain sections of the population such as obese individuals."
“The results suggest there are significant benefits of controlling air pollution in reducing a major risk factor for cardiovascular deaths ,the leading contributor to deaths in our country," he said.
A Lancet report released in 2019 said that more than five lakh people died prematurely in India in 2016 because of dangerous levels of outdoor air pollution.