Residents in a pollution hotspot cannot find out whether they were exposed to illegal levels of toxic gas last year, because their air monitor was switched off.
Two consecutive years of data are now incomplete after the monitor in Finchley Road, Swiss Cottage, was off for six months, making it impossible to know whether Camden Council breached pollution laws.
It is illegal for the average annual concentration of Nitrogen Dioxide (NO2) to exceed 40 microgrammes per cubic metre of air.
When the monitor was switched off on September 14, hourly concentrations had been frequently exceeding 40 microgrammes and the annual mean had hit 39.3.
In June, the concentration peaked at 203 microgrammes.
Low levels at other times, like the middle of the night, kept the average just below the legal cap.
But whether it stayed there by the end of December, as cold weather saw the use of heating systems increase, will remain unknown.
The council said the monitor had “reached the end of its useful life”, so it had worked with the Environment Agency to replace it.
It said this involved “extensive electrical, ground and earth works”, requiring “lane closures and temporary diversions”.
But residents still questioned the time taken.
Dr Jo Davis, of Greencroft Gardens, felt pollution had improved since TFL scrapped a Covid-related lane closure on Finchley Road.
“However, I am quite upset that the pollution data has been lost,” she added.
“I cannot believe that the works took six months to complete and that there was no Plan B to monitor the air pollution levels for our safety.”
Calvin Po, a Conservative candidate in Hampstead, is fighting plans to redevelop the O2 Centre, in part over fears the works will worsen pollution.
“I think six months of missing air quality data conveniently covers up Camden Labour’s neglect of the Finchley Road area and its questionable air quality strategy,” he said.
He said losing the O2 Centre would “force people to drive further out to access basic amenities.”
The replacement of the air monitor was completed on March 14 and data will soon begin appearing online, said Camden Council.
Adam Harrison, Labour’s lead member for air quality, was approached for comment.
For more, read:
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules here