Tiny chemical particles in the air people breathe are linked to an overall increase in risk of death, according to a recent study NBC News reported.

Researchers from New York University said this kind of air pollution involves particles so small they are invisible to the human eye. They found that even minuscule increases in the amount of these particles (by 10 micrograms per cubic meter of air, for example) lead to an overall increased risk of death from all causes by 3 percent -- and roughly a 10 percent increase in risk of death due to heart disease. For nonsmokers, the risk increase rises to 27 percent in cases of death due to respiratory disease.

These fine particles are usually made of harmful chemicals such as arsenic, selenium, and mercury, and can also transport gaseous pollutants, including sulfur and nitrogen oxides, with them into the lungs, UPI reported.

"Our data add to a growing body of evidence that particulate matter is really harmful to health, increasing overall mortality, mostly deaths from cardiovascular disease, as well as deaths from respiratory disease in nonsmokers," George Thurston, lead study investigator and a professor of population health and environmental medicine at NYU Langone, said in a statement. "Our study is particularly notable because all the data used in our analysis comes from government- and independently held sources."

Thurston said fine particles can contribute to the development of potentially fatal heart and lung diseases because they slip past the body's defenses and can be absorbed deep into the lungs and bloodstream. They are not sneezed or coughed out the way larger natural particles, like airborne soil and sand, are removed from the body's airways.

For the study, researchers surveyed more than 500,000 Americans from California, Florida, Louisiana, New Jersey, North Carolina, Pennsylvania, and the metropolitan areas of Atlanta and Detroit between the years 2000 and 2009. They calculated the death risk from exposure to particulate matter for people in each national census district and then statistically ruled out other variables impacting health and longevity including age, race or ethnicity, level of education, marital status, body size, alcohol consumption, how much participants smoked or not, and socio-economic factors such as median neighborhood income and how many people in the neighborhood did not graduate from high school.

The findings are detailed in the journal Environmental Health Perspectives.