A busy stretch of town centre road is the most polluted area of Kent.

Upper Stone Street in Maidstone has consistently failed to meet safe levels of air pollution, and in 2018 was worst hotspot for unclean air in the county.

The 500-metre section of road south of the town centre had the highest level of harmful nitrogen dioxide (NO2) in all of Kent at 77.2ug/m3, down from 79.3ug/m3 the previous year, according to countywide figures recently released by Friends of the Earth.

Although in 2019 there was another slight improvement, with a highest recorded figure of 75.2ug/m3, this still dramatically exceeds the Annual Air Quality Objective of 40ug/m3 of NO2, which is currently legally binding under European Union law.

Despite the numbers breaching safe levels, Maidstone Borough Council points out a trend of overall improvement, with six of its seven of monitoring locations in Upper Stone Street showing reduced NO2 levels in 2019 compared to the previous year.

The leading cause of NO2 pollution is emissions from road traffic, made worse since this stretch of road is regularly gridlocked during peak times.

Another factor behind the dirty air in this location is what has been described as the 'Canyon Effect' of having tall buildings close to the edge of the carriageway, preventing pollution from dissipating more easily. There are concerns the council may have inadvertently aggravated the problem by approving high-rise apartments currently under construction at Wrens Cross.

Airborne particulate matter, another type of air pollution, was a factor in 5.5% of deaths in Maidstone borough in 2013, slightly above the national average of 5.3%.

Proposals to improve air quality on Upper Stone Street, including the potential for a congestion charge, have previously been considered by MBC, which in April 2019 declared a climate emergency.

However the MBC 2020 Air Quality Annual Status Report has found that many of the possible changes could risk moving the problem elsewhere or would not speed up improvements enough to warrant their introduction. It also cited a lack of funding for more ambitious plans.

The report states: "In 2019, MBC commissioned a project to review options for improving air quality in Upper Stone Street. This was a development of an action to undertake a feasibility study into a Low Emsission Zone.

"The project was originally envisaged as being centred on the High Street but in the last couple of years, we have not measured any exceedances of any AQ [air quality] objectives in the High Street. The focus of the project was therefore shifted to Upper Stone Street, where despite recent improvements and a continuing downward trend, significant exceedances of the NO2 annual mean objective remain."

"The project was also broadened out to include consideration of a large number of other measures to improve air quality in the area. Unfortunately the measures studied were considered to be too expensive, too impractical, or would have been likely to simply shift the problem away from Upper Stone Street to another location.

"The impacts of three of the more promising measures were modelled but none was predicted to bring compliance with the objectives forward by more than about a year."

These three measures looked at but since disregarded were a formal red route, a voluntary scheme involving HGV and bus operators being asked to operate their cleanest vehicles on routes running up Upper Stone Street, and a Clean Air Zone which non-compliant buses, taxis and HGVs would have been required to pay a charge to use.

Steps now being taken by the council include consultation with Kent County Council on a less restrictive 'red route' solution preventing illegal stopping on the worst-affected stretch, and the addition of so-called 'green infrastructure' which would naturally help reduce pollution.

However there is no plan for a formal red route, which in other parts of the country indicates a road where all stopping for loading or unloading, and boarding or alighting from a vehicle, is prohibited.

A spokesman for MBC said: "Certain species of plants and trees are known to absorb nitrogen dioxide.

"Green walls, which grow up the sides of buildings, show the most promise and the consultant is investigating where these could be installed in Upper Stone Street and how much of a reduction in NO2 they might achieve."

Despite ongoing efforts to tackle the problem of dirty air in the borough - which has also been found to be an issue in the area of the former Wheatsheaf pub in Loose Road - environmental campaigners say much more can be done.

The Green Party in Maidstone responded with anger at the council's air status report, dismissing it as containing "self-congratulatory claims".

Reacting to the publication of the report, released earlier this summer, the party's Donna Greenan said: "Air pollution in Maidstone continues to kill and Maidstone remains one of the most polluted towns in the country outside of London so we were shocked to the council’s new self-congratulatory report on air pollution.

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"Lower and Upper Stone Street remain above legal limits for air pollution, damaging the health of people living there and those using the road. In some cases readings were nearly twice the legal limit.

"The council not only fails to bring in simple measures such as anti-idling enforcement, it claims that air pollution levels below the legal limit are a success. This is simply complacency, air pollution kills at levels below the legal limit too.

"The council needs to be taking concerted action, not giving itself a pat on the back."

Solutions the Greens propose - "a real green travel plan for Maidstone" - include an ultra-low emission zone, improved infrastructure for cyclists, a light rail service, trolley and electric buses, and a better environment for pedestrians.

Dr Edward Garrett, a GP at Brewer Street Surgery in Maidstone, believes much more should be done to encourage people out of cars in favour of walking and cycling.

He said: "Of the 7,699 words in KCC’s Keep Maidstone Moving public consultation, only 25 words referred to an improvement in cycling infrastructure encouraging people out of their cars in the very first place. That tells you all you need to know about KCC’s priorities for cleaner air and non-polluting travel in Maidstone."

Borough councillor Clive English, whose High Street ward includes Upper Stone Street, said: "We are trying our best to mitigate the current impact.

"We have taken some steps to try and deal with that, to try to introduce a red route. We are also looking at putting in pollution-removing trees in the next year or so."

His fellow Liberal Democrat ward member, Denise Joy, backs the idea of 'red route' style traffic measures to reduce stopping on Upper Stone Street.

She said: "There is a long way to go, but we are going in the right direction.

"It is not just affecting the people who live in the area, but also those walking there. It's not pleasant, but it will not get better unless we do something about it."

Air pollution is associated with a number of illnesses and is recognised as a contributing factor in the onset of heart disease and cancer. It particularly affects the most vulnerable in society, such as children, older people and those with heart and lung conditions.

Throughout 2019, MBC officers continued engaging with local schools through a Clean Air for Schools project, explaining the children about the causes and dangers of air pollution.

Nine dual electric vehicle charging points have been installed within MBC off-street car parks in Maidstone town centre, providing 18 individual charging bays which motorists with electric cars can use for cost of normal pay and display parking charges.

The council is also working with bus companies to have cleaner models operating routes which run along Upper Stone Street.

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A spokesman for MBC said: "There is a long term trend of improvement in air quality in Maidstone which has been going on for the last five years.

"In the majority of areas of Maidstone, there has been a year on year decrease in NO2 levels. MBC monitors in approximately 70 locations every year. However, there is always one or two locations which buck the trend if you only compare one year to the next, which could have been affected by a local issue such as roadworks.

"Upper Stone Street is unique in Maidstone, and not representative of other areas.

"It’s a major north-south route which is very busy. It has two lanes of traffic going up a fairly steep hill, meaning that vehicle engines work harder, and as the road is narrow in places, the pollution is less able to disperse. Although levels on this road are still high, they do show the same long term downward trend that all sites in our area show."

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