There has been no significant impact on air quality in the country due to the eruptions of Mount Sinabung volcano in north Sumatra, said the Department of Environment (DOE).

DOE in a statement Thursday said that Air Pollution Index (API) reading was recorded at an unhealthy level at 3 pm yesterday (Wednesday) in Cheras, Kuala Lumpur (API 107), Ipoh and Perak (API 124) due to the concentration of ozone on high ground when the observations were made.

According to the DOE, the formation of ozone on the earth's surface occurs every day in the early afternoon especially in big cities like Kuala Lumpur packed with traffic flow.

"Emissions of volatile organic compounds (VOCs) and oxides of nitrogen oxides emitted from motor exhausts act naturally under the influence of sunlight to produce a high concentration of ozone on the earth's surface.

"The high concentration of ozone on the surface of the earth does not last long and occurs for only one to two hours. Consequently, this phenomenon has causA man looks at Mount Sinabung which spews ash following eruption in Tiga Kicat, North Sumatra, Indonesia, Thursday, Feb 6, 2014. -AP Photo/Binsar Bakkaraed the air quality in big cities packed with traffic to become unhealthy for a short period of time," DOE said.

DOE also reported that API readings recorded at 10 am Thursday showed that 33 areas recorded good air quality, 19 areas moderate and no unhealthy levels were recorded.

Following the hot and dry weather, the DOE has activated the Open Burning Prevention Action Plan in all states.