Researchers have linked pollution to nine million deaths in 2015 - that's three times more than AIDS, Malaria, and Tuberculosis combined - with the world's poorest countries suffering the most.

A report prepared by The Icahn School of Medicine in New York City, and appearing in the British medical journal The Lancet, says countries like Somalia and Bangladesh where pollution could account for up to a quarter of deaths.  Most of the countries with high death rates related to pollution were in South Asia or Africa's Sahel.  Brunei and Sweden - both wealthy nations - had the lowest numbers of pollution-related deaths.

"Pollution is much more than an environmental challenge - it is a profound and pervasive threat that affects many aspects of human health and well-being," said the study's author Professor Philip Landrigan.

The figure of nine million deaths is about one in six deaths.  Of that total, air pollution accounted for 6.5 million deaths.  Water pollution accounted for 1.8 million deaths, and pollution in the workplace was linked to 800,000 deaths globally.