The US Environmental Protection Agency (EPA) has revised the airborne lead standard for the first time in 30 years, reducing the maximum permissible concentration by 90%.

The new standard of 0.15 micrograms per cubic metre is within the range recommended by a science advisory panel that evaluates air quality issues. By comparison the UK standard is 0.25 micrograms per cubic metre.

Environmentalists have generally praised the decision, although some say that the EPA missed a chance to curb emissions even more. A separate panel, focused on children's health, had recommended levels 7.5 times lower than the new standard; exposure to lead has been linked to negative effects on IQ and learning in children.

Lead emissions have dropped by 97% since 1980 in the United States, owing largely to the elimination of leaded petrol, according to the EPA.