Londoners breathe easier in their Ultra Low Emission Zone

The area of reduced traffic has lower air pollution

Low emission zones (LEZ) have been established in cities across Europe. Currently there are more than 250 such urban areas in which heavy duty trucks and other vehicles that pollute more than their fair share are partially or fully restricted. Some cities, such as Brussels, can have very strict restrictions.

The largest LEZ, at a little over 1,000 square miles, was established in Greater London on February 4th, 2008, restricting the travel of the most polluting of diesel cars and trucks, buses, larger vans, and minibuses. It does not apply to cars and motorcycles. Inside that LEZ is an Ultra Low Emission Zone (ULEZ), which as of October of 2021, covers 3.8 million Londoners. Every vehicle traveling in the ULEZ has to meet very tight emissions standards.

Two researchers, Anna Bornioli, and Hannen Bishop, recently looked into the effectiveness of this ULEZ, measuring levels of particulate matter and nitrogen dioxide, two pollutants associated with vehicular exhaust that can have health consequences. They found that for the most part the ULEZ was effective in reducing the pollution, although levels remained higher than European Union legal limits in some cases. They published their results in the July/August issue of the Journal of Public Health

Almost four million londoners live in the ULEZ. Photo: AutoServe autoservefleet.co.uk

Besides carbon dioxide and carbon monoxide, vehicle exhaust contains particulate matter, what most people would call soot and smoke. Researchers and health officials designate particulate matter by its size. PM10 are inhalable particles that are 10 micrometers or smaller in diameter. PM2.5 are smaller still, 2.5 micrometers or smaller. (For comparison, a human hair is about 70 micrometers in diameter.) Breathing in these particles can result in them embedding in your lungs or even entering your bloodstream. According to the EPA, breathing in particulates can lead to irregular heartbeat, aggravated asthma, decreased lung function, premature death in people with heart or lung disease, and heart attacks.

A pollutant resulting from diesel exhaust is nitrogen dioxide, which can also cause health problem, such as bronchial inflammation, coughing and wheezing, reduced lung function, and increased asthma attacks.

Besides raininess, London weather is known for stagnant air, leading to the city having infamous pollution problems. Starting in the 1600s, industrial pollution and the burning of coal fires to heat homes resulted in London “pea soupers,” in which fog mixed with soot and other pollution created smogs so thick they blotted out the sun. The most infamous of these, the Great London Pea Souper of 1952, resulted in 4,000 extra deaths during the five days of the smog attack, and another 8,000 more died in the next two months as a result of the smog. The disaster resulted in air pollution regulations that rid the city of these killer smogs.

Bornioli and Bishop used data gathered by Imperial College London from 16 monitoring systems within the ULEZ and four monitoring systems outside the ULEZ. Their results showed a significant reduction in nitrogen oxide levels within the ULEZ compared to the data they found outside the pollution control area. The results were more mixed for particulate matter. For the most part, reductions were minor, with only three of the collection sites having statistically significant reductions.

The difference in the pollution reductions might be because the nitrogen oxide is a direct tailpipe pollutant, whereas particulate matter can come from other sources, such as tires. As a matter of fact, tires produce more particulate matter than tailpipes. If London or any other city wants to really reduce vehicular pollution, they may need to further restrict vehicles, even if they are electric vehicles. The other confounding factor might be the nature of London’s stagnant air holding in pollution from areas adjacent to the ULEZ.

Though some of the reductions were less than desirable, the authors point out that any reduction in pollution has public health benefits. Besides studies like this one, longitudinal studies comparing the health of residents within the ULEZ with those who live outside the zone could give us greater knowledge of the health benefits derived from the ULEZ or other LEZs.

I’ve only read about LEZs in Europe. No such zones have been tried in the U.S. But they might be worth a try. While I was researching for this post, I ran across this article discussing LEVs. It contained this map of San Diego.

Map from The Union of Concerned Scientists ucsusa.org

I live not far and work not far from those ultra red zones with the highest particulate matter pollution. If they ever start LEVs in the United States, I know which city they can start with, and I can even tell them which neighborhoods would be a good starting point, too.

For more environmental science & news follow me on Twitter @EcoScripsit.