The Expert Panel on Air Quality Standards (EPAQS) has recommended an air quality standard for lead of 0.25µg/m3 as an annual average. This is stricter than the 0.5µg/m3 figure recommended by the World Health Organization and proposed as a new EC standard (ENDS Report 273, p 42 ).
The Government has already set a statutory air quality objective of 0.5µg/m3 to be met by 2005. Environment Minister Michael Meacher said the case for tightening this figure in line with EPAQS' recommendation will be considered in the current review of the national air quality strategy, due for completion at the end of 1998 (ENDS Report 270, pp 34-35 ).
Lead has a wide range of toxic effects. At low levels the main impact is on the central nervous system - particularly the developing brains of children.
A wide range of studies point to an inverse relationship between blood lead and intelligence, EPAQS says, with no evidence of a threshold "no-effect" level. The Panel accepts that action to protect children should take account of all sources of exposure - but points out that lead in air can increase exposure via food, soil and dust as well as by direct inhalation.
EPAQS says that lead levels in air of 1µg/m3 could be linked to an "unacceptable" average reduction in population IQ of one point. A 0.25µg/m3 standard would, it says, take account of uncertainties in the relationship between blood lead levels and airborne lead and allow for variations in childrens' susceptibility.
Both the existing official objective and EPAQS' tougher proposal are already met in most urban areas. Annual lead levels at a kerbside monitoring site in West London fell from about 1.4µg/m3 in the mid-1980s to 0.15µg/m3 in 1996.
The decline mirrors a seven-fold reduction in lead emissions from vehicles from 1980 to 1996. Unleaded petrol now holds over 70% of the market, and EC proposals will ban its use in all but "classic" cars from 2000 (ENDS Report 269, pp 43-44 ).
But the reduction in traffic emissions has made industrial sources increasingly prominent. In 1995, industry accounted for over a quarter of lead releases.
The Department of Environment, Transport and the Regions monitors lead levels around three metal processing works. An annual average of over 3.5µg/m3 was recorded near IMI's copper smelter in Walsall in the late 1980s, falling to 0.6-0.9µg/m3 by 1996. Recent monitoring found lead levels near Brookside Metals' copper smelter in Walsall and Industrial Metals' lead refinery in Newcastle of up to 0.36 and 0.55µg/m3, respectively.
Monitoring by local authorities in the West Midlands suggests that smaller industrial processes may also cause elevated lead levels.2 A high proportion of samples taken near a ferrous foundry in Sandwell and a lead-crystal glassworks in Dudley exceeded the 0.5µg/m3 level - with median values rising to 1.6 and 2.7µg/m3, respectively. The study pointed to a high contribution from "fugitive" sources, and also to relatively high background levels - perhaps caused by other industries nearby.
The DETR is now planning a more detailed research programme to assess the degree to which industrial lead emitters may lead to air quality problems across the UK.
The DETR is carrying out a review of EPAQS' finance, management and policy functions.
Several industry bodies have called for the Panel to be disbanded. The Chemical Industries Association accuses EPAQS of failing to take on board industry comments, and complains that the DETR has adopted the panel's proposals "essentially unchanged" without taking full account of costs and benefits.
However, the National Society for Clean Air says that EPAQS' work has been "notably successful" - and says it is "essential" that a body set up to assess medical risks should not be dragged into issues of risk management. The NSCA sees a future role for EPAQS in reconciling UK and EC air quality standards and reacting to new health findings - particularly in the fields of exposure and chronic effects.