Why have our skies been so hazy?

   TwitCount
Arnico Panday
Bhaskar Singh Karky

In recent years Nepal has been increasingly plagued by air pollution. We cough through the dry season while days with clear views of the Himalayas become rarer. Several obvious domestic sources contribute, including open fires, vehicles, cook stoves, brick kilns and other industries.  But Nepal is also a significant importer of air pollution: Satellite images and computer simulations show pollutants emitted on the heavily populated Indo-Gangetic plains crossing into Nepal and climbing up our valleys and slopes from October until May. 

Over the last month much of Nepal has been shrouded in particularly heavy haze, making even the nearest hills barely visible. The new atmospheric observatory near Sauraha, Chitwan, recorded concentrations of PM2.5 (fine particles smaller than 2.5 micrometers) reaching a peak on 10 April 2016 that was nine times WHO standards. Satellite images show that on many recent days the haze was much denser over Nepal than over the surrounding lower regions. The Chitwan station also recorded relatively high humidity, which allowed individual  particles to get a thick coating of water, reducing visibility.

At ground level the hills have been glowing with forest fires.  From a hilltop in Gorkha we watched every night over 20 patches of forest fire that looked like long orange chains wrapped across the hills. NASA satellites picked up a small fraction of the forest fires around Nepal (and missed most of the ones we saw in person), they still picked up record numbers of forest fires in Nepal and NASA ran a headline article on the topic.  

In mid-April local community forest user groups in Gorkha told us that many areas have not received any rainfall in the last eight months. Everyone was concerned about wild fires and the drying of springs. The atmosphere was hazy across the district. The smell of smouldering wood and fly ash from the burning sal forest hung in the air. 

So how do the forest fires start?  Certain human activities are responsible for almost all of the fires.  First, many farmers like to burn forested hillslopes to remove undergrowth so that new grass can emerge. Farmers have insufficient forage at this time of year, and new grass that follows the burning provides much needed fodder for livestock. Second, farmers like to use fire to clear agricultural land. Given the acute shortage of farm labour across the country, farmers resort to this labour saving technique for land preparation. Winds and dry storms are common in spring. In prolonged drought conditions, as was the case this year, what starts off as controlled burning can very quickly become a wildfire climbing up the slopes. In Gorkha, field preparation was the most common source of wild fires, even though there is no scientific basis to the idea that burning agricultural land increases productivity. Third, people also start forest fire on the slopes above the agricultural land so that the forest ash can easily be shovelled down to the fields and applied as fertilizer. Fourth, some fires are caused by carelessness (such as thrown cigarette buds) and some are a deliberate acts of destruction. Forest monitoring and patrolling is mostly done during  daytime, but many of the fires are started in the evening or at night.

With this year’s prolonged drought, community forest user groups are seriously concerned about wildfire that not only destroy forests grown over years, but also threaten homesteads and livestock. Numerous people have been injured while trying to control and fight fires. The number of fires and the area burned have been unusually high this year, mainly due to the prolonged drought. Not only has it resulted in a lot more dry grasses and other fuel that can quickly catch and spread fires, but it has reduced the fodder available for farm animals, resulting in more pressure to burn off dry grasses to allow new grass to grow. The drought may be attributable to the very strong 2015-2016 El Nino, during which changes in surface water temperature in the Pacific Ocean result in major shifts of wet and dry areas around the globe. 

It is illegal to set forests on fire in Nepal, but enforcement is weak. Forest management operational plans give insufficient attention to ban enforcement, focusing primarily on fire lanes (many are too narrow to be effective) and on general awareness programmes such as disseminating prohibition orders via FM radio. District Forest Offices, Community Forest User Groups, and District Development Committees have insufficient tools and trained human resources to deal with wildfires. To effectively reduce wildfires, forest operational plans must address the accumulation of drymatter in the dry season. More training and equipments must be given. Imposing punishment and fines must be the starting point so that people are more cautious when lighting open fires. Introducing zero tillage is another way to reduce the need to spread fire for agricultural land preparation. 

While the recent forest fires have increased haze to alarming levels, the air was by no means clean before that; the forest fires merely added pollution on top of already high levels. Air pollution levels, in the few places where measurements take place, have been far above WHO limits during much of the winter and spring. Really improving air quality in Nepal requires cleaning up the brick kilns or switching to construction materials that don’t need baking. It requires installing, maintaining and using pollution control equipment on industries, and it requires switching to importing low sulfur fuel and installing diesel particulate filters on diesel generators and vehicles. It requires a stronger and more effective push towards cleaner cooking, shifting the remaining 4 million households away from traditional biofuel cookstoves. In addition, we need to collect data that allows quantifying the fraction of Nepal’s air pollution that is imported from beyond the country’s borders, and to speak out regionally and internationally to push for reduction of emissions beyond Nepal’s borders.