EPA to improve public health
The Environmental Protection Agency (EPA) in the United States has tightened air quality standards to help improve public health.
It is lowering the amount of smog forming ozone permitted in the atmosphere for the first time in more than 10 years.
Health and environmental campaigners wanted more stringent limits, but industrial players lobbied aggressively against them.
Industry leaders said complying with the new standards would prove expensive.
The EPA accepts the scheme will cost billions, but said it will help save 4,000 Americans from dying prematurely.