Science.

Monsoon gained momentum in the last week with 20% above normal rains helping narrow down the deficit across the country to 4% below normal. The showers also help purify the air by converting some pollutants into water soluble substances. The disappearance of the haze that envelops north India during December to March, resulting from crop burning and vehicular emissions, with the onset of monsoons is a case in point. However, not all pollutants gets washed way and end up spreading across the globe, according to a paper published in the journalDuring rains, some of the pollutants remains in the air and moves up higher, ending up in the stratosphere above an altitude of 20 kms. When pollutants reach this altitude, they spread all over the world.Scientists found that about 10% of the harmful sulphur dioxide was spread this way. Scientists used a research aircraft in 2015 to carry out their measurements between Cyprus and the Maldives at an altitude of 9 to 15 kms. They found that India was the major source of pollutants, not China.