Factories and oil refineries in southern California face a new crackdown on their emissions of air toxins, after experts in the state reported that breathing in pollution carries almost three times the risk of causing cancer than was previously thought, especially for children and babies.



Air quality regulators covering almost 11,000 square miles that are inhabited by almost 17 million people, including residents of Los Angeles, have approved new rules designed to help protect the public from poisons such as arsenic, benzene and heavy metals in industrial emissions.

The move follows a report from state officials that estimated that the cancer risk from toxic air contaminants to be nearly three times as high as previously thought, the Los Angeles Times reported.

Southern California business groups have objected to the prospect of tighter controls. The Los Angeles County Business Federation warned officials to “avoid unnecessarily alarming the public”.

Depending on their levels of toxic emissions, industrial concerns could be required to take measures ranging from further reducing pollutants pumped into the air to warning nearby residents of the health risks of the emissions.

The new rules were agreed on Friday by the South Coast Air Quality Management District (SCAQMD) governing board, the air pollution control agency for a region which is inhabited by half of the population of California and is the second-most populated urban area in the US. It is also “one of the smoggiest”, according to the regulator’s website.

The SCAQMD covers stationary sources of air pollution, such as power stations, oil refineries and manufacturers, which with households produce 25% of the area’s ozone-forming pollution. The other 75% comes from mobile polluters such as road vehicles, trains and planes. Emissions standards for mobile sources of pollution are covered by state and federal bodies, the SCAQMD said.

Air pollution in southern California has been falling for decades because of increased regulation, but now regulators want to go further.

Officials are responding to scientific studies over the last decade that show young children and infants to be more sensitive to toxic air pollutants than previously thought. Past estimates were based on adults. Inhaling industrial pollutants early in childhood could significantly raise the risk of developing cancer later in life, experts have found, according to the LA Times report.

Pump jacks are seen at sunrise near Bakersfield, California. Photograph: Lucy Nicholson/Reuters

More than 30 other districts in California are making changes based on the new state-issued health risk guidelines, but the region covered by the SCAQMD suffers from very high levels of pollution.

Last year, Los Angeles had 94 “smog days”, when pollutants in the air exceeded federal standards – up from 88 in 2013, according to regulators. In the 1970s, the number was regularly above 200.

Residents of southern California contend with the highest cancer risk from air pollution in the state, according to regulators.

The current rules for the region cover about 400 industrial facilities. Around 90 will be affected by the new rules. Regulators intend to measure emissions of the facilities to which they issue operating permits and notify those which need to issue warnings, hold public meetings and cut emissions.