All forms of pollution were responsible in 2015 for an estimated 9 million premature deaths-16% of all deaths worldwide. Pollution is thus the world's largest environmental cause of disease and premature death.

The vast majority of these deaths are due to exposure to air pollution. mostly from small particles that can penetrate deep into the lungs (known as PM2.5). Young children, those with preexisting health conditions such as asthma and old people are particularly vulnerable. In total, nine out of ten people now breathe polluted air, mostly in low-middle income countries.

It is not just pollution from cars and industry that are causing this health crisis, poor indoor air quality is also deadly. In half the world, this is due to having no access to clean fuels or electricity, and so have to rely on inefficient solid-fuel burning stoves and kerosene lamps technologies Globally, 9/10 people now breathe polluted air which kills 7 million people every year. (Ambient air pollution: 4.2 million deaths; household air pollution: 2.8 million deaths)