Impact of ambient air pollution on blood pressure (BP) in adolescents varies by different pollutants, suggests a study involving adolescents living in London and published in the journal PLoS One.¹ The systolic BP increased with long-term exposure to higher levels of fine particulate matter, but it was found to decrease upon exposure to higher levels of nitrogen dioxide (NO2).

Researchers from the UK, China, Brazil and USA examined the association between exposure to air pollution, particularly nitrogen dioxide (NO2) and particulate matter (PM2.5, PM10) and BP in adolescents. For this they sourced data of 3284 adolescents from the Determinants of Adolescent Social Well-Being and Health (DASH) study from 51 schools. The participants were followed up from age 11-13 years to 14-16 years.

Results showed that with every μg/m3 increase in NO2, the systolic BP decreased by 0.30 mmHg among girls and 0.19 mmHg in boys. On the other hand, with an increase in PM2.5 by 1 μg/m3, the systolic BP increased by 1.34 mmHg in girls and 0.57 mmHg in boys. These associations persisted even after adjusting for ethnicity, socioeconomic status or body size.

When this study was done, it was anticipated that long-term exposure to air pollution would be associated with high BP, the analysis however threw up unexpected findings. Exposure to high levels of NO2 was associated with decrease in systolic BP, whereas exposure to high levels of PM2.5 was associated with increase in systolic BP. These associations were particularly stronger among girls than in boys. It was  hypothesized that the gender difference in physical activity could be a possible explanation for this disparity in the associations. More boys participated in sporting activities at baseline (31%) vs girls (15%). This difference was also evident at follow-up; 28.5% vs 19.3%, respectively. Although the researchers have advocated more studies to verify these contrasting observations, nevertheless they add to the growing evidence of impact of ambient air pollution on health in adolescents. They further reiterate the necessity to devise ways to reduce air pollution to “maximise the health benefits of physical exercise in young people”.

Reference

1. Karamanos A, et al. Associations between air pollutants and blood pressure in an ethnically diverse cohort of adolescents in London, England. PLoS One. 2023 Feb 8;18(2):e0279719. doi: 10.1371/journal.pone.0279719.