The introduction of ultra-low emission zone (ULEZ) in central London earlier this year and other measures have led to “dramatic improvements” in London’s air quality since 2016, according to a report that was released on Saturday.

Some challenges remain, but new modelling by experts from the Environmental Research Group at Imperial College of pollution in 2019 shows that, even before lockdown, measures implemented by mayor Sadiq Khan since 2016 have helped transform London’s air quality.

The number of Londoners living in areas exceeding the legal limit for NO2 (nitrogen dioxide) fell from over 2 million in 2016 to 119,000 in 2019, a reduction of 94%. However, the challenges include most residents still facing particulate matter exceeding the limit set by the WHO.

Besides, research shows that those exposed to the worst air pollution are more likely to be from Black, Asian and minority ethnic communities. There is also emerging evidence linking air pollution with an increased vulnerability to the most severe impacts of the Covid-19 pandemic, officials said.

The ULEZ charge of £12.50 per car levied since April applies to pre-2015 diesel and pre-2006 petrol cars that fall foul of Euro 6 and Euro 4 standards, respectively. The ULEZ charge for heavier vehicles, including lorries and buses, is £100 per day.

The report is likely to lead to the ULEZ being expanded to cover more areas because 24% of roads in inner London still exceed the legal limits for NO2. The challenge is greater for particulate matters since most of London does not meet WHO limits.

The mayor’s office said that the ULEZ had contributed to a reduction of 44% in roadside NO2 in the central London zone. There are now 44,100 fewer polluting vehicles being driven in the central zone every day with 79% of vehicles in the zone now meeting ULEZ emissions standards.

Khan, who faces the next mayoral election in 2021, said, “I was elected (in 2016) on a mandate to deliver hard-hitting measures to tackle our toxic air crisis. Today’s report confirms the transformative impact that my policies have had in just four years.”

“However, air pollution remains a major public health challenge and it’s time for the government to step up, set ambitious national targets, and provide the powers and funding we need to consign air pollution to the history books,” he added.

Deputy mayor for environment, Goa-origin Shirley Rodrigues, said, “The ULEZ is the centrepiece of our plans to clean up London’s air. We have and are implementing the boldest plans of any city on the planet and the ULEZ is exceeding expectations.”