§ Mr. BurnsTo ask the Secretary of State for Transport whether his Department's design standards for ventilation in road tunnels are intended to deal with lead in vehicle emissions; and if he will make a statement.
§ Mr. Peter BottomleyYes. Road tunnel design standards control the dominant pollutants in vehicle emissions and set fresh air requirements for conditions when tunnel traffic is fully congested and emissions are at their worst.
The ventilation standards are for carbon monoxide and diesel smoke and can safely disperse the small quantities of lead to be found in some tunnel atmospheres. Even the unlikely event of a lengthy traffic delay would not cause tunnel users to remain in a tunnel long enough appreciably to increase their overall exposure to lead.
The issue of lead and health was considered by a Department of Health and Social Security working party on lead in the environment. After considering all sources of lead and the variability of short-term average exposures, it recommended that the annual mean concentration at places where people might be exposed to lead in air 410W continuously and for long periods should not exceed 2 mg per cubic metre. The same limit was subsequently adopted in EEC directive No. 82/884—Council directive on a limit value for lead in air. The working party did not recommend, and the directive does not impose, any limits for short term exposures for lead in air, but the Health and Safety Executive sets occupational health limits in its guidance note EH 40/88 "Occupational Exposure Limits 1988". These are based on average exposures ever eight-hour periods and would be relevant to tunnel maintenance workers, in particular those allowed to work in tunnels which remain fully or partially open to traffic. In such cases it is standard practice for tunnel ventilation systems to remain in operation.
There is no evidence to suggest that lead arising from vehicle emissions in tunnels increases health risks significantly for tunnel users, maintenance workers or nearby residents. In longer tunnels the environment is continuously regulated and in all cases tunnel exhaust shafts and portals are sited to minimise the impact of tunnel pollution on the immediate vicinity. The steps now taken to protect those working in or living close to tunnels from any adverse effects from tunnel pollution will be reinforced by the reduction of levels of lead in petrol, the increasing availability of unleaded fuel and the implementation of the requirement that from next year all new cars should be capable of running on unleaded petrol.