COLOMBO, Nov. 11 (Xinhua) -- Sri Lanka's air quality is soon returning to normal as the air quality index has reached moderate levels from above 100 recorded last week, the state owned National Building Research Organization (NBRO) said here Monday.

Senior Scientist at the NBRO, Sarath Premasiri told Xinhua that the air quality index over the island had lowered to a moderate 60 to 70 by the weekend from the above 100 recorded last week and it no longer posed a health risk on the citizens.

"The situation is returning to normal and the air pollution is going away. According to our data, the situation is not hazardous anymore," Premasiri said.

Sri Lanka's air quality reached cautionary levels last week as the Air Quality Index fluctuated between 112 to 173, reaching far above the normal levels, the NBRO said.

The standard level of AQI is measured at around 50 or below.

Premasiri said the prevailing severe air pollution in New Delhi, India may have been one cause for this but added investigations were ongoing to ascertain all the causes for the unhealthy air pollution prevailing in the island country.