In 1970, Congress pushed forward the Clean Air Act, which took aggressive steps to monitor and control pollutants in the environment via federal regulations. Over the years, people living in the United States have been exposed to considerably fewer contaminants such as lead and carbon monoxide.

But as a new study in the Lancet medical journal points out, pollution continues to be a global crisis, and one that might carry a far more devastating mortality rate than previously believed. Analyzing the complete picture of contaminated regions around the globe, study authors believe pollution killed 9 million people in 2015—more than smoking, AIDS, war, or deaths from hunger.

The study’s authors aggregated premature deaths on a global basis that were attributable to pollution, singling out certain regions that continue to struggle with high concentrations of toxic materials. In India, one in four premature deaths (2.5 million) was related to environmental contamination. In China, 1.8 million people died due to illnesses connected to poor air quality.

A lack of regulatory oversight in these areas is largely to blame. Dirty fossil fuels, crop burning, and burning garbage plague India; industrial growth in other locations often leads to pollution that isn’t being monitored or controlled. Roughly 92 percent of deaths as a result of poor environmental conditions are in low- or middle-income countries [PDF].

The study also notes that the 9 million estimate is conservative and likely to rise as new methods of connecting pollution-related illness with mortality in a given area are discovered. It’s hoped that increased awareness of the problem and highlighting the economic benefits of a healthier population (lower health care costs, for one) will encourage governments to take proactive measures.

[h/t Phys.org]