Particulate matter monitored at â€˜very highâ€™ and â€˜moderateâ€™ levels at several sites in London on Wednesday and Thursday (January 16-17) due to low wind and cold weather
Particulate matter was monitored at â€˜highâ€™ and â€˜very highâ€™ levels at various sites in London this week due to low wind and cold air, according to Kingâ€™s Collegeâ€™s Environmental Research Group (ERG).
The highest level of PM 10 was monitored at a station in the City of London on Upper Thames Street near Monument station, which peaked at 10 â€“ the top of the scale â€“ according to the ERGâ€™s London Air website.
Also in the City of London, a station on Beech Street recorded peak levels of PM 10 at nine on the scale, as did a monitoring station in Brent, North West London, near the north circular road.
Several sites also monitored pollution levels in the â€˜moderateâ€™ banding (from four to six), such as stations in Knightsbridge, Euston Road in Camden and on Old Kent Road in Southwark.
According to the London Air site: â€œLow wind speeds and cold settled air led to poor pollution dispersion on 16th and 17th January 2013. This caused PM10 to reach â€˜very highâ€™, the top level of the Daily Air Quality Index, at two locations in London along with widespread â€˜moderateâ€™ PM10, PM2.5 and nitrogen dioxide.â€
It added that the Upper Thames Street station measured â€œsignificantly higher PM10 levels than most other busy roadside sites.
â€œWe suspect that there could have been an additional local contribution from the resuspension of road salt in this busy enclosed location.â€
However, commenting on nitrogen dioxide levels, the site said: â€œA change to snowy conditions has brought about an improvement in air pollution concentrations, though two sites (Westminster – Oxford Street and City of London – Upper Thames Street) have continued to measure â€˜moderateâ€™ nitrogen dioxide.â€
Air pollution levels in the UK, including particulate matter, are monitored using the index approved by the Committee on Medical Effects of Air Pollution Episodes (COMEAP). This system uses a 1-10 index, with monitored levels of air pollution from 1-3 considered â€˜lowâ€™, 4-6 â€˜moderateâ€™, 7-9 â€˜highâ€™ and pollution levels reaching 10 considered â€˜very highâ€™.
More information is available on the Kingâ€™s Collegeâ€™s London Air website.