To ask the Secretary of State for Transport what information his Department collects on pollution levels in the vicinity of the toll booths on the Dartford-Thurrock crossing, broken down by (a) hour of the day, (b) month and (c) season. (107517)

An annual survey of air quality in the toll booths is carried out. However the results are not broken down by (a) hour of the day, (b) month and (c) season.

The results of this annual survey are compared with the Health and Safety Executive’s Occupational Exposure Standards (OES). The most recent survey, completed in August 2006, showed that all the results achieved the OES.