Long-term exposure to tiny air pollution particles known as PM2.5 is linked with higher blood pressure in teenagers living in London – with stronger associations seen in girls, according to research.

Scientists from Kings College London, who analysed data from more than 3,000 adolescents, also found that exposure to high levels of nitrogen dioxide (NO2) – a pollutant from diesel traffic in London – is associated with lower blood pressure in this group.

The team said that based on its findings, published in the journal Plos One, more research is urgently needed to assess how air pollution may be affecting the cardiovascular health of children and adolescents.

Senior author Seeromanie Harding, a professor of social epidemiology from King’s College, London, said their study “provides a unique opportunity to track exposures of adolescents living in deprived neighbourhoods”.

She added: “Given that more than one 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 to (and opportunities for) young people’s development.”

Tiny pollution particles are small enough to be inhaled into the body.

These pollutants can make their way into the bloodstream, causing damage to blood vessels and airways.

The findings highlight the potential detrimental role of exposure to higher concentrations of particulate matter on adolescents’ blood pressure levels – Dr Alexis Karamanos

For the study, the researchers examined the effects of air pollution on children attending 51 schools across London.

They analysed data from 3,284 adolescents, following up from ages 11-13 and 14-16 years old.

The results show Particulate Matter (PM2.5) – tiny pollutants that come from car exhaust fumes, building, and industry materials – was associated with higher blood pressure across all ages, particularly among girls.

Meanwhile, NO2 was associated with lower blood pressure.

Co-author Dr Andrew Webb, from King’s College London, said: “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 of nitrate-rich vegetables.”

Researchers also found teenagers from ethnic minority groups were exposed to higher annual average concentrations of pollution at home than their white UK peers.

But, they added, the impact of pollutants on blood pressure did not vary according to ethnicity, weight, or economic status.

Corresponding author Dr Alexis Karamanos, from King’s College London, said: “The findings highlight the potential detrimental role of exposure to higher concentrations of particulate matter on adolescents’ blood pressure levels.

“Further studies following the same adolescents over time in different socio-economic contexts are needed to understand whether and how exposure to higher pollutant concentrations may affect differently the cardiovascular health of children and adolescents.”

Air pollution particles ‘linked to higher blood pressure in London teenagers’ | Times Series