NAPLES, Italy, Jan. 9 (UPI) -- Natural gas, believed to be among the cleanest of fuels, emits ultrafine airborne particulate matter when burned in home appliances, Italian researchers say.

Patrizia Minutolo, Andrea D'Anna, Mario Commodo, Rocco Pagliara, Giuseppe Toniato, and Claudio Accordini of the Universita Federico II at Napoli and colleagues used advanced optical diagnostic tools, particle collection methods and particle size assessment to identify particulate matter with diameters in the range of 1 nanometer to 10 nanometers.

The researchers conclude that while these particles were present in relatively high concentrations in the flame region of home heating burners, these were strongly oxidized, resulting in very low emissions.

In contrast, domestic stove tops emitted larger amounts of these very small particles, the researchers say.

These type of emissions have been associated with increased mortality due to deposition in the lungs, brain and circulatory system, the researchers say.

The findings are published in Environmental Engineering Science journal.

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