California rules tobacco fumes as toxic as diesel exhaust
California, the state that pioneered workplace smokefree legislation, has ruled that tobacco smoke should be classified as a "toxic air pollutant".
The ruling means that second hand cigarette smoke is now considered as dangerous as diesel exhaust fumes and could lead to tougher regulations on smoking.
The California Air Resources Board said that passive smoking had been directly linked to a range of cancers and respiratory diseases.
The ruling put California "way ahead", said John Froines, chairman of the Board's Scientific Review Panel.
While only 16 per cent of Californians smoke, 56 per cent of adults and 64 per cent of adolescents are exposed to cigarette fumes.
The decision to reclassify tobacco fumes was triggered by a report last year which claimed that second hand smoke was directly linked to breast cancer in young women.
It also linked tobacco smoke to premature births, asthma and health problems in children. Some health experts say that the ruling could have an international influence on the way tobacco is regulated.