Declining levels of aerosols -- particles that make up smog and air pollution -- could be making heatwaves more common compared to greenhouse gas emissions, especially in populated areas of the world, according to a study.

Aerosols, which are being studied for their role in global warming -- the particles can cause a cooling effect by reflecting sunlight back into space -- can also produce a warming effect by absorbing solar radiation and influencing cloud formation.

Researchers, led by those at The University of Texas, US, said that recent studies have linked the lowering of aerosols with rising regional temperatures.