Scientists have discovered a tiny particle one thirtieth the width of a human hair which they claim plays a key role in pollution and climate change.

Researchers from Harvard University studied atmospheric particles, highly lethal air pollutants which appear everywhere in the atmosphere, but are more common above cities, the Daily Mail reported.

The tiny particles play a key role in air pollution and climate change by providing a surface for chemical reactions and reflecting and absorbing radiation.

The particles switch between absorbing and reflecting light – affecting the heating cycles of the planet.

Researchers discovered that these particles separate into distinct chemical compositions during their life-spans. Depending on the composition, the rate of chemical reactions and the amount of light that the particles reflect and absorb will change over time.

This could impact how air becomes polluted and the processes behind climate change – the warming of the earth.

The study will be published in the Proceedings of the National Academy of Sciences.

“We’ve confirmed experimentally that changes in relative humidity can separate the organic and inorganic material in individual atmospheric particles into distinct liquid phases, much like oil separates from water,” Allan Bertram from the University of British Columbia, who worked on the report, said.

“We need to understand as much as possible about the chemical composition, physical properties and interactions of atmospheric particles if we’re going to assess how they impact human health, regional weather patterns, and even global climate change,” Bertram was quoted by the paper as saying.