Air pollution is the greatest external threat to human life expectancy, the latest Air Quality Life Index found.

Breathing in fine particulate matter take an average of 2.3 years from a person's life expectancy.

That's about the same impact of smoking and seven times that of HIV/AIDS.

The report looked at the impact of PM2.5 particles in the air which are less than 2.5 micrometers in diameter.

That's a fraction of the width of the human hair.

PM2.5 particles can't be seen with the naked eye, but can enter your lungs and even reach your bloodstream.

These tiny particles are emitted by the burning of fossil fuels and forest fires.

South Asia has four of the most polluted countries on Earth. People in Bangladesh, India, Nepal and Pakistan are expected to lose five years of life expectancy on average.

In Africa, the Democratic Republic of the Congo, Rwanda, Burundi, and Republic of the Congo are among the 10 most polluted countries in the world. Air pollution is as much a health threat in Central and West Africa as HIV/AIDS and malaria.

In 2021, 20 out of the top 30 most polluted counties in the United States were in California due to the impact from wildfires.

China’s pollution has declined 42.3 percent since 2013, the year before the country began a "war against pollution.”

Now the average Chinese citizen can expect to live 2.2 years longer, however pollution in China is still six times the WHO guideline, taking 2.5 years off life expectancy, the report found.

Funding to fight air pollution is much less than other efforts, the study's authors say.

Global funding for HIV/AIDS, malaria and tuberculosis totals $4 billion a year.

While only $34 million in philanthropic funds goes to fighting air pollution in Europe, the U.S. and Canada.

And $1.4 million to Asia (not including China and India), and $300,000 to the entire continent of Africa.

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