Provisional measurements suggest that the European Union Limit Value for NO2 has just been exceeded in London for 2011.

The Limit Value has two parts, an annual mean of 40 ug m-3 as a measure of long term exposure and an hourly mean concentration of 200 ug m-3, as a measure of short term exposure, which should not be exceeded more than 18 times per year.

The Wandsworth Putney High Street Site has now measured 31 hours (6th January, AM) with a mean concentration of 200 ug m-3. The site is located at the kerbside in a busy pedestrian area. A further monitoring site on the nearby building facade has measured 10 hours with NO2 above 200 ug m-3 and a monitoring site in Knightsbridge has measured 13 hours above 200 ug m-3.

Item date 06/01/2011