Cleaner air can go a long way in saving lives, according to a new report out Friday. It found that policies and laws aimed at curbing emissions are often linked to reductions in hospitalizations, premature births, and deaths in just a few weeks after their enactment.

The review looked at past studies that evaluated major pollution reforms that took place throughout the world, as well as historical data on local deaths and illnesses following their ratification. It was conducted by the environmental committee of the Forum of International Respiratory Societies (FIRS), a coalition of professional organizations focusing on improving lung and respiratory health.

In the U.S., for instance, they found that the closing of a Utah steel mill in the mid-1980s was linked to less overall air pollution during the winter and a lower number of hospitalizations, school absences, and deaths caused by lung problems like asthma within a 13-month span. In Ireland, the first week of a public smoking ban saw a 26 percent reduction in reported heart attacks as well as 32 percent reduction in strokes, compared to the week before. And during the 2008 Olympics in Beijing, China, policies that limited factory emissions and travel in the area were linked to fewer visits to the doctor related to asthma and fewer deaths related to cardiovascular problems during the next two months.

The report’s findings were published in the Annals of the American Thoracic Society.

“We knew there were benefits from pollution control, but the magnitude and relatively short time duration to accomplish them were impressive,” lead author Dean Schraufnagel, a researcher at the University of Illinois at Chicago and longstanding member of the American Thoracic Society, said in a statement released by the University of Birmingham, whose researchers also contributed to the report.

Despite the lack of success in driving down carbon emissions as a whole, countries across the world have made strides over the past few decades in reducing many of the sources of air pollution most dangerous to human health. And it’s not just lives these policies have saved.

Citing research by the U.S. Environment Protection Agency, for instance, the report noted that levels of sulfur oxides, nitrogen oxides, carbon monoxide, and other major pollutants fell 73 percent between 1990 and 2015 in the country, thanks to amendments added to the Clean Air Act. These reductions are thought to have saved the country $2 trillion in health care costs—a savings of 32 times what it took to implement the reductions.

But given that air pollution still directly contributes to the deaths of over 4 million people annually, according to the World Health Organization, there’s obviously plenty of room for improvement in driving down emissions further.

“Air pollution is largely an avoidable health risk that affects everyone. Urban growth, expanding industrialization, global warming, and new knowledge of the harm of air pollution raise the degree of urgency for pollution control and stress the consequences of inaction,” Schraufnagel said.

It’s an urgent call that will likely continue to go unheeded by the current White House, which is working to roll back certain environmental protection measures.