Stretches of two busy roads have been marked as pollution hotspots.
Keycol Hill, Sittingbourne, and St Pauls Street, Milton Regis, have been declared Air Quality Management Areas (AQMA) after tests found they breached levels set by the government.
A report prepared for Swale council’s cabinet committee said the highest level of nitrogen dioxide recorded at Keycol Hill was 78.6ugm-3 - almost double the level allowed by the government.
Exposure to excessive amounts of the gas irritates the airways of the lungs and can worsen the symptoms of lung diseases.
St Pauls Street, which was already listed as an AQMA for its high levels of nitrogen dioxide, has now been redesignated for breaching levels of PM10, tiny chemical particles. That happened on 42 days in 2019.
At its most polluted, the road registered a reading nearly three times the highest recommended level.
The report said: “Regular exceedances of the daily mean limit for PM10 are relatively rare in this type of residential/urban location adjacent to a ‘B’ class road.”
It is a legal duty to report such breaches and set up an AQMA. Once one has been declared, councils have to draw up a plan to manage the pollution, and open that up to public scrutiny.
Pollution levels are recorded using small plastic tubes which feature a mesh plate covered in a chemical designed to absorb the gas.
Results are used to assess whether the area has a high or low concentration of pollution.
Cabinet member for environment, Cllr Tim Valentine (Green), said monitoring had continued throughout lockdown. Levels of pollution remained high, despite fewer cars on the roads, but there had been a drop in nitrogen dioxide.