The Obama Administration today unveiled new restrictions on ozone pollution that tighten the current limits for the first time since 2008, but fall short of the stricter regulations public health and environmental agencies had pushed for. The new regulations limit the standards for ground-level ozone—the smog-causing emissions that come from tailpipes, factory smokestacks, and power plants—from 75 parts per billion (ppb) to 70 ppb. The U.S. Environmental Protection Agency (EPA) estimates the new regulation will result in up to $38 billion in public health benefits, including fewer asthma attacks and emergency room visits.

EPA had initially suggested a limit of somewhere between 65 and 70 ppb, indicated in the draft rule released last November. Industry groups lobbied for the limit to be left at 75 ppb, while public health urged a limit even lower than 65 ppb. EPA’s Clean Air Scientific Advisory Committee last year stated that a limit of 70 ppb would provide “little margin of safety for the protection of public health, particularly for sensitive populations.” NACCHO and a coalition of public health groups had previously communicated support for a standard of 60 ppb to the EPA.

Exposure to smog causes a host of health problems, including asthma and heart disease, and it is thought to be a factor in premature death. Exposure is particularly hard on children, the elderly, and people with pre-existing heart and respiratory conditions. More than 4 in 10 Americans live in areas where pollution levels are often too dangerous to breathe, according to the American Lung Association’s State of the Air 2015 report. A Harvard study estimates that air pollution kills 3.3 million people a year worldwide.

Today’s decision follows a federal directive for EPA issue a final rule by October 1, 2015. After the Obama administration withdrew a 2010 proposal to reduce ozone emissions, environmental and public health groups sued the administration, and a federal judge required EPA to produce a result by today.

The new regulation is expected to face legal opposition from both industry and environmental agencies.