What's the biggest killer of people in developing nations? The answer will surprise you.

If you had to guess the biggest killer of people in the developing world, what would you say?

A funeral pyre in India...

HIV/AIDS?  Malaria?  Influenza?  Malnutrition? 

Nope.  Pollution.

According to a recent essay in Ensia magazine, in 2012, air, water, and other forms of pollutants killed some 8.4 million people in developing nations.  That's more people than died from HIV, tuberculosis, and malaria combined.

And by these measures, mortality from Ebola is a mere drop in the bucket.

Pollution not only kills people directly.  It often worsens or increases the incidence of other diseases, such as heart disease, cancers, respiratory diseases, chest infections, and diarrhea. 

Scientists are increasingly warning people with health concerns -- such as obesity, diabetes, and respiratory problems -- to stay indoors during periods of rush-hour traffic, when air pollution is heaviest.

Globally, some 9 million people die from pollution annually, according to the World Health Organization.  Given that over nine-tenths of these deaths occur in developing nations, it is apparent that deadly pollution is increasingly a problem concentrated in the developing world.

As Southeast Asia continues to see heavy smoke palls from forest burning that send thousands of people to hospitals, and as plumes from forest fires stretch for thousands of kilometers across the Amazon, we have to remember that environmental destruction doesn't just kill nature.

It kills lots of people too.