The study found that two thirds of the soot particles in brown haze originate from biomass burning, and only one third from fossil fuel sources.
For the study, Orjan Gustafsson, from Stockholm University in Sweden, and colleagues measured the proportion of an isotope called carbon-14, or radiocarbon, in soot particles collected from a mountaintop site at Sinhagad, India, and from the Maldives in the Indian Ocean.
Radiocarbon decays with a half-life of around 5700 years. In fossil fuels there is very little of the isotope because it has had millions of years to decay, whereas the relatively youthful nature of biomass (plants and animals) means the radiocarbon signature is high.
The researchers found that around two thirds of the soot had a high radiocarbon content, indicating that its source was biomass burning.
The remaining third of the soot contained no radiocarbon, and was most likely formed during combustion of fossil fuels.
The new findings indicate that this small-scale biomass burning is a major contributor to the brown haze.
According to Gustafsson, urging people to switch from wood burning to solar-powered stoves, or gas, would significantly diminish the brown haze.
"The effect would be large and quick - improving air quality and reducing global warming," New Scientist quoted him, as saying. (ANI)