London: Pollution caused nine million deaths in 2015 - three times more than AIDS, tuberculosis and malaria combined - scientists said on Thursday, calling for governments in poor countries to act.

India fared worst, with 2.5 million people dying early because of pollution, followed by China with 1.8 million deaths, according to The Lancet Commission on Pollution and Health, a two-year initiative seeking to highlight the issue.

One in six of all deaths worldwide are caused by pollution, and the vast majority occur in developing countries, the report in The Lancet medical journal said.

‘With globalisation, mining and manufacturing shifted to poorer countries, where environmental regulations and enforcement can be lax,’ said Karti Sandilya, one of the authors and an adviser to environmental group Pure Earth.

‘People in poorer countries - like construction workers in New Delhi - are more exposed to air pollution and less able to protect themselves from exposure, as they walk, bike or ride the bus to workplaces that may also be polluted.’

In contrast, many people in developed countries commute to air-conditioned offices in air-conditioned cars, he told the Thomson Reuters Foundation in an email.

Exposure to high levels of air pollution, especially over many years, can affect human respiratory and inflammatory systems, and can lead to heart disease, stroke and lung cancer.

Billions in developing countries cook on open fires with wood or coal, exposing people - mainly women and children—to dangerous fumes.

But rapidly industrialising nations are worst affected and regulation could help to protect health as they develop, said the commission, which brings together more than 40 international health and environmental authors.