Improving air quality — in clean and dirty places — could potentially avoid millions of pollution-related deaths each year. That finding comes from a team of environmental engineering and public health researchers who developed a global model of how changes in outdoor air pollution could lead to changes in the rates of health problems such as heart attack, stroke and lung cancer. Outdoor particulate air pollution results in 3.2 million premature deaths annually, more than the combined impact of HIV-AIDS and malaria. The researchers found that meeting the World Health Organization’s (WHO) particulate air quality guidelines could prevent 2.1 million deaths per year related to outdoor air pollution.