Dundee air quality and pollution levels as LEZ comes into force

Enforcement of Dundee’s Low Emission Zone (LEZ) began on May 30 in an effort to improve the city’s air quality.

Encircled by the A991, the LEZ covers approximately 461,000 metres squared or 0.178 miles squared.

But what do we know about the air quality of the area? We mapped out the six air quality monitoring sites in Dundee, and analysed the data.

The LEZ is being introduced to help parts of the city stay within the Scottish Air Quality Objective of annual mean nitrogen dioxide levels of 40µg/m3.

But on a daily basis, the Seagate site has seen daily peaks nearly double that – reaching 79.7 µg/m3 of nitrogen dioxide on February 15, 2021.

In the last few years, the Whitehall Street station saw a peak just below that at 70.4 µg/m3 on the same day.

Just outside the LEZ, Dundee Meadowside nitrogen dioxide levels reached as high as 90.1 µg/m3.

But the Whitehall Street station has seen a fall in annual peaks since 2021.

So far this year the highest recorded daily mean at the station was 49µg/m3. Could the LEZ have had an impact even before enforcement?

The low emission zone has faced increased scrutiny in the months running up to enforcement so we take a deep dive into the data behind the move.

We also spoke to Professor Jill Belch, clinical professor at the University of Dundee’s School of Medicine about the impact of air pollution on health and why pollution levels peak at certain times of the year.

Which areas of Dundee are tracked?

The Air Quality in Scotland website brings together data from a number of monitoring sites across Scotland in order to track air pollution levels.

In Dundee, there are six different sites – Broughty Ferry Road, Lochee Road, Mains Loan, Meadowside, Seagate and Whitehall Street.

The Low Emission Zone (LEZ) is aimed at improving air quality by only allowing vehicles which pass certain emissions standards to enter the zone.

The area in which it is operational is shown in the map below.

Whitehall Street and Seagate are within the LEZ, while Meadowside lies slightly outside it.

Lochee Road, Mains Loan and the Broughty Ferry sensors are outside the city centre.

Dundee’s air quality

We have looked at data for nitrogen dioxide levels between January 1, 2021 and May 1, 2024 for all six sites within Dundee.

The data, taken from Air Quality Scotland, tracks the daily mean levels of nitrogen dioxide.

While the Scottish Air Quality Objective is an annual mean, it is still helpful to look at daily means as even day-by-day spikes can impact health, according to Professor Jill Belch.

The peak nitrogen dioxide among these measuring sites was observed at Meadowside on January 10 2022 at 90.1 µg/m3. This is followed by Lochee Road with a level of 89.2 µg/m3 on February 15 2021.

These are both over double the target level set of 40ug/m2.

Lochee Road in Dundee. Image: Kim Cessford / DC Thomson

The two areas within the LEZ have lower peak levels, but not by much.

Seagate saw a high of 79.7 µg/m3 on February 15 2021, while Whitehall Street’s highest level since January 2021 was also on February 15 2021 at 70.4 µg/m3.

Burning fossil fuels produces nitrogen dioxide, and the UK Government Department for Environment Food and Rural Affairs (DEFRA) states that high levels can inflame airways.

Across all of the measuring sites in Dundee, Lochee Road has the highest average level of nitrogen dioxide.

It may not have the highest peaks, but over the past three-and-a-half years, it has seen an average nitrogen dioxide level of 29.6µg/m3.

The second highest average is in Seagate, which is within the LEZ, at 28.8µg/m3, followed by Meadowside at 26 µg/m3.

These figures were calculated by taking the average of the data from each site between January 1 2021 and May 1 2024.

Although sites have seen peaks in the 70s and 80s, these are considered low levels of air pollution still.

Seagate in Dundee. Image: Steve MacDougall/DC Thomson

Whitehall Street, which is within the LEZ, had an average level of 22.9 µg/m3 for the time period.

DEFRA states that low levels of nitrogen dioxide are under 200, moderate is between 201-400µg/m3, high is between 401 and 600µg/m3, and very high is 601µg/m3 or more.

These levels are based on the hourly mean figure.

No site in Dundee has exceeded low levels of nitrogen dioxide since 2021.

However, the World Health Organisation guidelines on air pollution suggest nitrogen dioxide concentrations should not exceed 10 µg/m3 annual average or 25 µg/m3 in the daily mean.

Levels at the Seagate generally remain within the target, however have reached over double the Scottish target of 40µg/m3.

Peaks tend to be measured within colder months, typically October to February.

Since the LEZ was introduced [in May 2022 before a two-year grace period], the highest level of nitrogen dioxide seen has been 66.2µg/m3 on January 21 2023, compared to the pre-introduction level of 79.7µg/m3 in February 2021.

In Whitehall Street, the number of times the air pollution levels have exceeded the 40µg/m3 target are fewer than seen at Seagate, however are still over target.

Again, most of the spikes are seen over the winter months.

Like in Seagate, the levels of nitrogen dioxide reached have been lower since the LEZ was introduced. Since June 2022, the highest level reached has been 54.9µg/m3 on January 21 2023, compared to the peak of 70.4 in February 2021.

The impact on health

Professor Jill Belch, clinical professor at the University of Dundee School of Medicine, has raised awareness of the impacts of air pollution on adults and children alongside colleagues at the Tayside Pollution Research Programme, which cross-referenced data on admissions to Ninewells Hospital compared to the levels of air pollution.

The research showed that children may be at a higher risk of hospitalisation at lower levels of NOx pollution exposure than adults.

Speaking about the impacts of the LEZ on health, she said: “We looked at high pollution within hospital admissions. For adults and children, there were much higher admissions to hospital on days where there was high pollution.

“There is no safe level in going over the limit. In adults, we were seeing people come in with heart attacks, strokes, lung infections. Children are admitted in lower levels [of air pollution] than adults.

“It doesn’t just cause lung problems in kids, we saw people admitted with gut disease, because pollution dissolves in the saliva. It can affect the skin and causes eczema.

“We are doing a study in two years to compare the hospital admissions, we hope to show the admissions will have gone down.

“Unfortunately there’s not an LEZ covering the whole city but it’s an absolute benefit for the people who work and walk there.”

Professor Jill Belch of the University of Dundee spoke of the impact of air pollution on health. Image provided by the University of Dundee

She added: “If you look at the air pollution data, it goes up in rush hour and down in the evening. If you don’t want to be affected, go out at night.

“A lot of the winter peaks is down to still air. We’ve got those really cold days where the air doesn’t move, and one of the big issues we’ve got in the world is wood burners. We need to make people aware of the issues, it’s like having a diesel truck in your front room.

“In the summer, the pollution is blown away. In summer holidays people aren’t driving as much, in the winter people take their cars more and they also idle to keep themselves warm.

“I’m thrilled to see the LEZ being introduced. People don’t just stop when you get to the LEZ, you’ll get the bus in or get a different car so the areas around it benefit as well.

“If people want to drive in it, they’re going to have to change their car.

“A lot of the issues are in cars like 10-year-old SUVs. Someone who is less well off might opt for a smaller petrol car, and most of them will be okay.

“I think that when the scheme was introduced, people won’t decide to wait until June 1 to get a new car that’s compliant, in the past two years they’ll have already done it so we’ll already be seeing those impacts.”