When raging blazes across Indonesia’s jungles resulted in thick haze, which also covered parts of Malaysia and Singapore, they were labelled a “crime against humanity” in a portrayal of their deadliness, as the forest fires were said to be responsible for up to half a million cases of respiratory infections.

Of late, thick blanket of haze covering the Kathmandu Valley has become a cause of concern.

The haze has been attributed to active forest fires in Nepal as well as other South Asian countries.

Since March 16, there has been a significant rise in the concentration level of aerosols released from biomass burning, hence the thick haze.

For the past one week, Kathmandu and several other parts of the country have been shrouded in thick blanket of haze, with increased concentration of particulate matter, which experts say, is enough to penetrate deep into the lungs.

Air quality monitoring stations set up in Bode in Bhaktapur district to measure aerosols, which include urban haze, smoke particles and dust in the atmosphere, have showed higher concentration of such particles since March 16.

“This is an indication that there are combustion sources (biomass burning or fuel burning) which give rise to these particles,” said Maheswar Rupakheti, group leader at the Institute of Advanced Sustainability Studies (IASS) based in Germany.

IASS and International Centre for Integrated Mountain Development (Icimod), in collaboration with National Aeronautics and Space Administration (NASA), has set up monitoring stations in Bode and Pokhara to measure Aerosol Optical Depths (AOD), an indicator for the concentration of fine particulate matter (urban haze, smoke particles) in the atmosphere.

“Normally when AOD is higher than 0.3, the atmosphere is considered polluted, and data from Bode and Pokhara show that there was a continuous increase in haze since March 16,” said Rupakheti.

According to him, active forest fires, along with agro-residue burning, in the Indo-Gangetic plains have resulted in high concentration of pollutants—smaller than one micrometre in diameter—which are harmful to human health.

Various studies have found that trans-boundary haze pollution resulting from vegetation fires and forest fires is considered a serious environmental challenge and they pose serious health threat to millions of people living in the region.  

An image released by NASA on March 22 showed widespread crop fires across India along the Indo-Gangetic plains as a result of “slash and burn” agriculture practised by farmers.

Data compiled by Nepal Forest Fire Management Chapter (NFFMC) showed that on average, over 60 forest fires were recorded across the country in 24-hour period during March

this year.

On March 23, as many as 285 forest fires were identified in the country, while it was 125 and 120 on March 21 and March 20 respectively.

“In recent years, forests in Rasuwa and Nuwakot around the Kathmandu Valley are burning, releasing smoke and haze,” said Sundar Sharma, district soil conservation officer in Nuwakot.

“Peak forest fire condition is expected in the fourth week of April this year, given the current dry and windy weather condition,” added Sharma, who also manages the NFFMC.