Studies address air quality and heart health

A meta-analysis of 14 air pollution studies from around the world found that exposure to high levels of air pollutants during childhood increases the likelihood of high blood pressure in children and adolescents, and their risk for high blood pressure as adults, according to a new study published in the Journal of the American Heart Association.

High blood pressure during childhood and adolescence is a risk factor for hypertension and heart disease in adulthood. Studies on air pollution and blood pressure in adolescents and children, however, have produced inconsistent conclusions. This systematic review and meta-analysis pooled information from 14 studies focused on the association between air pollution and blood pressure in youth. The large analysis included data for more than 350,000 children and adolescents, with mean ages 5.4 to 12.7 years of age.

The analysis included 14 studies published through September 6, 2020, exploring the impact of long-term exposure (?30 days) and/or short-term exposure (<30 days) of ambient air pollution on blood pressure levels of adolescents and/or children in China and/or countries in Europe.

The studies were divided into groups based upon length of exposure to air pollution and by composition of air pollutants, specifically nitrogen dioxide and particulate matter. Most of the research linking heart disease with particulate matter focuses on particle matter mass, which is categorized by aerodynamic diameter, the researchers said. Fine particles are defined as PM2.5 and larger; coarse particles are defined at PM10; and the concentrations of particulate matter are typically measured in their mass per volume of air.

The meta-analysis concluded that short-term exposure to PM10 was significantly associated with elevated systolic blood pressure in youth. In addition, periods of long-term exposure to PM2.5, PM10, and nitrogen dioxide were also associated with elevated systolic blood pressure levels. Higher diastolic blood pressure levels were associated with long-term exposure to PM2.5 and PM10.

"Our analysis is the first to closely examine previous research to assess both the quality and magnitude of the associations between air pollution and blood pressure values among children and adolescents," said Yao Lu, MD, PhD, lead author of the study, professor of the Clinical Research Center at the Third Xiangya Hospital at Central South University in Changsha, China, and professor in the department of life science and medicine at King's College London, in a statement. "The findings provide evidence of a positive association between short- and long-term exposure to certain environmental air pollutants and blood pressure in children and adolescents."