Can clean-air zones make a difference? Most research indicates that clean-air zones help decrease air pollution. One of these zones, called Ulez, started covering central London in 2019 and inner London in 2021.
According to a report from City Hall, by October 2022, Ulez had managed to reduce harmful NO2 levels by about 46% near the roadside in central London and by 21% in inner London. Researchers at Imperial College London reviewed this report.
Interestingly, air quality got better even in places near the edge of the Ulez area. Similar improvements were noticed in Germany’s low-emission zones as well. This suggests that drivers were switching to cleaner vehicles instead of driving much farther just to avoid the zone.
Ulez had less impact on areas away from the roads. A study from 2021 found that during the first phase of Ulez (when it only covered central London), the reduction in NO2 levels across all of London was less than 3% on average. Changes in PM2.5 levels were not significant.However, this study pointed out that Ulez was just one part of a bigger plan to improve air quality. This plan included an older low-emission zone that covered all of London since 2008, and efforts to use cleaner buses and taxis. When you look at all these measures combined, the improvements in air quality are much more noticeable.
Other clean-air zones in places like Birmingham, Berlin, and Amsterdam have also reported decreases in air pollution. A few studies have shown mixed results. A review in 2015 of various clean-air zones in Europe found that schemes that limited both regular cars and heavier vehicles were usually more effective.
Different methods were used for these studies, but many of them considered other factors that could influence air pollution, like weather patterns, how much traffic there is, and the long-term reduction in coal use. What about the expansion of Ulez? About 90% of the cars you see in outer London already meet the emissions standards. Cars registered after 2005 for petrol and after September 2015 for diesel are generally exempt from charges.
People who drive older, more-polluting vehicles usually have to pay around £12.50 per day to enter the zone, although there are a few exceptions. Even though air pollution is worse in inner London, it affects health more in outer London. One reason for this is that there are more elderly people who are more vulnerable to its effects in outer areas.
A study requested by Transport for London predicts that extending the Ulez (Ultra Low Emission Zone) will cut down nitrogen oxide pollution by 6.9% in outer London, with not much change in fine particle pollution. This move is anticipated to lower the average NO2 levels by 1.5% in outer London. This means that, by itself, the Ulez expansion might not greatly improve air pollution, and the air quality would still not meet the standards set by the World Health Organization.
Yet, even small improvements can positively impact health. According to a report from Public Health England, clean-air zones can have a bigger effect if combined with other plans for cleaner transportation.
To truly make the air safe, we’ll also need to decrease air pollution from other sources like farming, building, and wood-burning in homes, as the report points out.
Informed by bbc.