Pollution killed 25 lakh Indians in 2015, the world's highest number of deaths caused by air, water and other forms of pollution, according to an international study. It also translates to five deaths every minute due to pollution in the country. China stood second with 1.8 million deaths attributed to pollution. Most of these deaths happened through heart diseases, stroke, lung cancer and chronic obstructive pulmonary disease (COPD), researchers said.