Blood pressure risk from PM2.5 exposure for teens in London

King’s College London has identified a link between fine particulate matter and elevated blood pressure in London teens living in deprived areas.

PM2.5, or fine particulate matter, refers to microscopic air pollution particles caused by everything from exhaust fumes and tyre wear to wood-burning stoves. Doctors consider these to be especially harmful due to their ability to find routes deep inside the body, building up over time, damaging organs and vital systems. 

The latest evidence of health risks associated with this form of pollution shows blood pressure in teens can increase when there is long-term exposure. A sample group aged between 11 and 16 years was used, in which a stronger link between PM2.5 and internal pressure was identified among girls. A total of 3,284 pupils at 51 schools across the city were involved, with systolic and diastolic blood pressure measured. 

The results are particularly concerning due to the sensitivity of bodies during teenage years. High blood pressure can lead to hypertension, heart attacks and strokes, and negatively effects internal organs which, at this stage, are still in development. This raises the risk of life-long complications. 

‘This longitudinal study provides a unique opportunity to track exposures of adolescents living in deprived neighbourhoods. Given that more than 1 million under 18s live in neighbourhoods where air pollution is higher than the recommended health standards, there is an urgent need for more of these studies to gain an in-depth understanding of the threats and opportunities to young people’s development,’ said Professor Seeromanie Harding, senior author. 

While PM2.5 was found to increase blood pressure, nitrogen dioxide (NO₂), which is associated with diesel fumes and as such one of the most predominant pollutants in London,  was found to have the opposite impact. Simply put, it actively brought blood pressure down. 

‘The effect of NO₂ on blood pressure is similar to what we and other researchers have observed previously after ingesting green leafy vegetables or beetroot juice. These are rich in dietary nitrate (NO₃^–), which increases circulating nitrite (NO₂^–) concentration in the blood and lowers blood pressure, an effect which may also be sustained over weeks or months with continued ingestion,’ added co-author Dr Andrew Webb. ‘As NO₂ also increases circulating nitrite (NO₂^–) concentration, this provides a potential explanation as to why elevated NO₂ appears to be associated with lower blood pressure in the adolescents.’

Last year, Air Quality News reported on a study that found NO₂ was leading to increased fatigue and depression in adolescents. 

Image: Christopher Campbell