Air pollution exposure may up high BP risk: study

Beijing: Exposure to air pollutants commonly associated with coal burning, vehicle exhaust, airborne dust and dirt may increase the risk of developing high blood pressure, a new study has warned.

"In our analysis of 17 previously-published studies we discovered a significant risk of developing high blood pressure due to exposure to air pollution," said Tao Liu from Guangdong Provincial Institute of Public Health in China.

"People should limit their exposure on days with higher air pollution levels, especially for those with high blood pressure, even very short-term exposure can aggravate their conditions," he said.

Researchers performed a meta-analysis of available published studies assessing the health effects of all air pollution on hypertension risk.

In the first study to simultaneously estimate the effects of short-term and long-term exposure to air pollutants on hypertension by meta-analysis, researchers focused on sulphur dioxide (SO2), which mainly comes from the burning of fossil fuel and nitrogen oxide (NOx), which comes from fossil fuels
burned at power plants and vehicle exhaust.

They also studied particulate matter (PM), which are particles found in the air, including dust, dirt, smoke and liquid droplets.

PM 2.5 is smaller than a speck of dust, and the most common and hazardous type of air pollution. PM10 includes both PM2.5 and PM2.5-10, researchers said.

The meta-analysis found high blood pressure was significantly associated with short-term exposure to SO2,PM2.5 and PM10; and long-term exposure to nitrogen dioxide (NO2), which is produced from combustion, and PM10.

Of the 5,687 air pollution studies initially identified, 17 were the focus of this - which involves more than 108,000 hypertension patients and 220,000 non-hypertensive controls.

High blood pressure was defined as systolic blood pressure more than 140 mm Hg and/or diastolic blood pressure over 90 mm Hg or by antihypertensive drug use, researchers said.

Air pollution exposure was assessed by averaging data from nearest air pollution monitoring stations, or using complex dispersion models or land use regression models, they said.

High blood pressure is a major risk factor for cardiovascular disease and stroke.

The findings were published in the journal Hypertension.