Researchers in the United States and China have discovered a curious link between air pollution and suicide rates that prompts us to reconsider how to approach this issue. China’s efforts to reduce air pollution have prevented 46,000 suicide deaths in the country over just five years, the researchers estimate. The team used weather conditions to tease apart confounding factors affecting pollution and suicide rates, arriving at what they consider to be a truly causal connection. The results, published in Nature Sustainability, unearth air quality as a key factor influencing mental health.