Environmental pollution – from filthy air to contaminated water – is killing more people every year than all war and violence in the world.

One out of every six premature deaths in the world in 2015 – about nine million – could be attributed to disease from toxic exposure, according to a major study released in The Lancet medical journal.

The financial cost from pollution-related death, sickness and welfare is equally massive, the report says, costing some $US4.6 trillion ($A5.9 trillion) in annual losses – or about 6.2 per cent of the global economy.

“There’s been a lot of study of pollution, but it’s never received the resources or level of attention as, say, AIDS or climate change,” said epidemiologist Philip Landrigan, dean of global health at the Icahn School of Medicine at Mount Sinai, New York, and the lead author on the report.

The report marks the first attempt to pull together data on disease and death caused by all forms of pollution combined.

“Pollution is a massive problem that people aren’t seeing because they’re looking at scattered bits of it,” Landrigan said.

Experts say the nine million premature deaths the study found was just a partial estimate, and the number of people killed by pollution is undoubtedly higher and will be quantified once more research is done.

Asia and Africa are the regions putting the most people at risk, the study found, while India tops the list of individual countries.

One out of every four premature deaths in India in 2015, or some 2.5 million, was attributed to pollution. China’s environment was the second deadliest, with more than 1.8 million premature deaths, or one in five, blamed on pollution-related illness, the study found.

Several other countries such Bangladesh, Pakistan, North Korea, South Sudan and Haiti also see nearly a fifth of their premature deaths caused by pollution.