Air pollution is a public health crisis and it is shocking that pupils are exposed to such high levels of harmful air.
Children are five times more exposed to harmful air pollution while travelling to primary schools in London than at any other time of the day, a new study claims.
More than 250 pupils aged between six and 11 wore backpacks containing sensors to monitor the air quality on their journey to and from five London primary schools.
They helped collect 490 million measurements from 2,000 journeys for the Breathe London Wearables Study, which was carried out by King's College London in spring 2019.
The results, published on Tuesday, found that children were on average exposed to five-times-higher concentrations of nitrogen dioxide (NO2) during the school run than when they were at school.
It also revealed that children who walked to school via backstreets were exposed to the lowest levels of NO2 pollution, even less than those travelling in cars and buses.
The study advised that children in the capital should avoid using busy roads to walk or cycle to school in order to reduce their exposure to pollution.
A total of 258 pupils carried 1kg sensors in their backpacks to measure N02 and fine particulate matter (PM2.5) for the study.
Particulate matter is a term used to describe the mixture of solid particles and liquid droplets in the air, while NO2 is a harmful gas released when fuel is burned.
The sensors, developed by Dyson, were carried by each child for five days and also recorded their GPS location.
Those taking part were from primary schools in Richmond, Greenwich, Haringey, Hammersmith and Fulham, and Kensington and Chelsea.
The study, funded by the Mayor of London in partnership with C40 Cities, found that children who walked to school along main roads received the highest concentrations of PM2.5 and NO2.
It said children were "particularly vulnerable" to the harmful effects of air pollution due to their "immature and developing immune system and lungs".
It comes as new data collected by Google Street View cars for the Breathe London project shows nitrogen dioxide is on average 51% higher on busy A roads, compared to quieter local roads.
The cars recorded the highest concentrations on Hanger Lane and other locations on the North Circular, Brixton Road and Kensington Church Street in London.
The locations are all to fall within the expansion of the new ultra low emission zone in 2021.
Mayor of London Sadiq Khan said: "Air pollution is a public health crisis and it is shocking that pupils are exposed to such high levels of harmful air.
"All the schools who took part in this study are using the results to educate pupils and their families on air quality and helping them find the least polluting routes for their journeys."
Luke Powell is a reporter with PA. Image: Ruben de Rijcke, via Flickr.