Sarath Premasiri, a senior scientist at the National Building Research Organization said the air quality has dropped by 150 percent when compared to what it was during the curfew.
The clean air resulted in mountains as far as Ratnapura and Kandy being visible in Colombo.
However, with more vehicles returning to the streets the air quality is expected to drop further over the next few days and the mountains are unlikely to be visible.
“When compared to the same period last year the air quality in Colombo these days is very good. But when we compare to what we saw during the curfew we see a big drop,” he said.
During the curfew, air pollution levels in Colombo ranged between 25 and 30 on the Air Quality Index.