Air pollution in Preston has fallen, figures reveal.
Climate campaigners say the improvement in air quality has been helped by continuing investment in cycling and walking as well as the transition to zero-emission cars with new petrol cars to be banned from sale by 2030.
Yet there are still areas across the UK where "toxic" pollution has led to health charities calling on the Government to impose stricter limits on fine particles in the air (PM2.5), which come mainly from the burning of oil, gas and diesel.
Figures from the Department for Environment Food and Rural Affairs show the average concentration of PM2.5 pollution particles in Preston was 7.8 micrograms per cubic metre in 2019 - below the UK limit of 25, and the World Health Organisation guideline limit of 10.
That was a decrease from 8 micrograms in 2018.
Across the North West, the level of PM2.5 was at 8.3 in 2019, and 7.9 in 2018.
Separate figures published by the NHS show an estimated 4.2 per cent of deaths among people aged 30 and over in Preston were associated with long-term exposure to PM2.5, down from 4.4 per cent the year before.
The UK Health Alliance on Climate Change welcomed the reduction in pollution in some areas, but wants the Government to bring in lower limits on PM2.5 as part of the Environment Bill, which will come back before Parliament this year.
Dr Yannish Naik, director of the advisory group, said: "The Government has taken some positive steps to reduce fine particulate pollution, including by accelerating the transition to zero-emissions vehicles, and increasing investment in cycling and walking.
"However, UK limits for PM2.5 pollution are still more than double the recommendations of the WHO, while air pollution contributes to around 40,000 deaths a year, with many more suffering from related diseases.
"To save lives, protect the environment and increase our resilience to future crises we call for the Environment Bill to include a legally binding commitment to reducing PM2.5 pollution in line with WHO guidance by 2030 at the latest."
The dangers of air pollution were highlighted last month when nine-year-old Ella Adoo-Kissi-Debrah became the first person in the UK to have air pollution listed as the cause of death on their death certificate.
Coroner Phillip Barlow, who found she had been exposed to high levels of PM2.5 from traffic, said the Government should reduce its limits for the particulate matter pollution to bring them in line with WHO guidelines.
In his report, Mr Barlow said: "Delay in reducing the levels of atmospheric air pollution is the cause of avoidable deaths."
PM2.5 are tiny particles, measuring about three per cent of the diameter of a human air, which can lodge in the lungs and even pass into bloodstream, potentially causing damage to blood vessels and organs.
They come mostly from traffic fumes, but also through industrial emissions, wood burners and livestock manure. A small proportion come from natural sources in the form of dust or sea salt particles.
Levels of the PM2.5 particles have fallen in England since 2011, when national records began, from 12.1 micrograms per cubic metre to 9.6 in 2019.
In Preston, the reading fell from 2011, when it was 10.2.
Defra’s readings for PM2.5 are calculated using air quality measurements along with numbers and locations of people in each local authority to provide average annual levels of exposure.
A spokesperson said: "We know there is more to do as we build back greener from the coronavirus pandemic.
“Through our landmark Environment Bill we have committed to a new concentration target on PM2.5 - the most damaging pollutant to human health - and as part of this we will be considering the WHO’s guidelines for PM2.5.”