As a coastal county with many beautiful green spaces and no major metropolises, you would be forgiven for thinking Sussex towns and cities had some of the cleanest air.

But this is not the case.

Brighton, Hastings, Horsham and Worthing were all above the World Health Organisation’s (WHO) guidelines for levels of particulate matter (PM) concentration (PM2.5) in 2023.

In fact, Hastings ranked as the seventh most-polluted place in England last year.

The measure of pollution is PM, which is everything in the air that is not gas and consists of a huge variety of chemical compounds and materials, some of which can be toxic.

PM2.5 is particulate matter less than 2.5 micrometres in diameter.

The WHO recommends levels of PM2.5 should be kept at 5μg/m³ or lower.

With an average of 9.6 μg/m³ of PM2.5, Hastings was the most polluted place in Sussex last year.

It was closely followed by Brighton at 8.9, Horsham at 8.4 and Worthing at 8.3.

The Argus: Hastings was ranked the seventh most polluted place in EnglandHastings was ranked the seventh most polluted place in England (Image: Ben Guerin/Unsplash)

A government spokesman said: “Due to the small size of many of the particles that form PM some of these toxins may enter the bloodstream and be transported around the body, lodging in the heart, brain and other organs.

“Therefore, exposure to PM can result in serious impacts to health, especially in vulnerable groups of people such as the young, elderly and those with respiratory problems.”

PM can be either man-made or natural with examples including dust, ash and sea spray. Particulate matter (including soot) is emitted during the burning of fuels, such as for power generation and in car engines.

Hastings Borough Council said its air quality is generally good and in 2022 there were “no exceedances of the UK air quality standards at any monitored location”.

The national air quality regulations require that the annual average of PM2.5 must not exceed 20μg/m³, which is four times the WHO’s recommended levels.

The council said road traffic emissions are the number one source of pollution in the town.

In Hastings’ latest Air Quality Annual Status Report, the council said: “Whilst air quality has improved significantly in recent decades, there are some areas where local action is needed to protect people and the environment from the effects of air pollution."