4-10 December 2015 #785

Every breath we take

Despite the drop in emission due to the blockade, pollution chokes Kathmandu Valley this winter

Photo: Kunda Dixit

Nepal’s petroleum imports are down to 20 per cent of normal due to the Indian blockade, yet Kathmandu’s legendary winter smog is as bad as ever.

The reasons include prevailing winds from the southwest blowing in transboundary pollution from the Indo-Gangetic plains, the increase in households burning firewood due to the gas shortage, and dust particles from unfinished road construction in the capital.

The worsening air pollution in northern India this winter is partly the result of burning of crop residue in Punjab and Haryana over the past month. Coupled with the increase in vehicular traffic this has made pollution so bad that New Delhi imposed odd-even number plate traffic restrictions this week.

“Satellite images show agricultural burning in Northern India and computer models indicate the smoke is transported all over the Indo-Gangetic plains including the Himalaya contributing to regional haze," said Bhupesh Adhikary, air quality specialist at ICIMOD (International Centre for Integrated Mountain Development) in Kathmandu.

Kathmandu's bowl shaped topography exacerbates the problem in winter by trapping warmer polluted air near the ground in a phenomenon known as inversion. The pollution is composed of dust particles, vehicular exhaust and brick kiln emissions.

The fuel crisis caused by the Indian blockade has brought down the level of vehicular pollution, and the earthquake damaged 80 per cent of the brick kilns. However, experts say the smog is almost as bad as last winter because of smog from the Indian plains and the dust from Kathmandu Valley roads that are half-complete because of the fuel crisis.

In October-November farmers in Punjab and Haryana in India burn their fields to clear paddy stubble after harvest to plant winter wheat. Farmers in the Nepal Tarai have also started to burn crop residue because of the spread of mechanisation. In recent year’s crop fires in Northern India are so extensive that they are visible on NASA satellites images.

The air pollution problem in the region can get worse as reports suggest India is building 297 and planning to build 149 coal-fired power stations by 2030. Add that to the already existing power plants, vehicles and brick kilns and we are in for compromised lungs not just in India but across the region.

"Since we cannot build a 3km tall curtain along our border, we have to tackle cross border pollution by working with other governments,” says Arnico Panday, senior atmospheric scientist at ICIMOD. “Global climate change may be beyond our control because it requires all the countries to work together especially the large ones. Regional air pollution control requires strong action especially in India, the largest emitter in our region.”

The fuel crisis has also forced households in the Valley and even restaurants and offices to burn firewood for cooking. Since it is a temporary measure, most don’t have proper chimneys or ventilation. Smoke from firewood has made morning smog worse, and also increased the risk of indoor pollution.

Household pollution was ranked number one risk factor for the number of years lost due to ill-health, disability or early death in 2010 according to The Global Burden of Disease: Generating, Guiding Policy, a study conducted by Institution for Health Metric and Evaluation, University of Washington, Human Development Network and The World Bank.

During a recent media training workshop on Air Pollution conducted by ICIMOD Arjun Karki, of Patan Insitute of Health Sciences said, "Inhaling various pollutants increases the risk of chronic obstructive pulmonary disease, respiratory tract infections, asthma, throat and lung cancer and pulmonary TB among others."

Sahina Shrestha

Controlling Contrails

Besides better known, and more notorious, air pollutants like diesel exhaust and roadside dust, there is emerging evidence that the contrails of aircraft flying at high altitude could make ground temperature cooler in winter and prolong smog. There is concern that a dramatic increase in airliner traffic on international air routes over northern India could increase the number and duration of combined jet contrails.

Contrails are wisps of ice particles formed by aircraft flying at high altitude and form under the right combination of temperature and humidity. Besides the carbon dioxide emitted by aircraft engines which contribute about 12 per cent of global warming from the transportation sector worldwide, contrails have not been studied as closely.

The impact of contrails on the temperature of the earth's surface is hard to measure because there is no control situation in which planes are not flying over a certain area. But after the 9 September 2001 attack on New York and Washington grounded all traffic over continental US for three days, scientists got a rare chance to study the effects of contrails. They found evidence of the heat-trapping capabilities of these artificial clouds, as well as reflection and blockage of the sun's rays combining to increase the average daily temperature range. But some researchers claim that this difference in surface temperatures may simply have been the result of natural variations in the climate.

Because the north Indian air routes have heavy night traffic because of all intercontinental flights between Southeast Asia and Europe, the contrails merge and are carried by prevailing winds over Nepal by morning. Given the right conditions, contrails can even expand into frontal system of high-altitude cirrus clouds. Experts say that contrails can block the sun, prolong the winter fog in the Indo-Gangetic plains and Himalayan Valleys by preventing the mist from being burnt off by the sun's warmth. On the other hand, the carbon dioxide in the atmosphere and the increase in water vapour in the upper atmosphere have a warming effect.

Scientists cannot confidently pinpoint what effects contrails have on the local weather conditions, but they think the overall effect is negative and compound existing problems of persistent fog and pollution. In addition, India's domestic aviation market is expected to grow 10 per cent annually in the next decade, which is double the growth rate of the global aviation industry, and airlines plan to add 600 business jets and small aircraft by 2020. Indian airlines already carry nine times more passengers than they did 20 years ago.

Aviation emissions haven't got as much attention as other fossil fuels as a contributor to global warming in climate change negotiations including the ongoing talks in Paris. Contrails have received even less attention. Yet, researchers suggest ways to counter contrails and reduce their impact on weather. One of them is to reroute flights so they don't fly through cold, high pressure systems with low humidity in the upper atmosphere. But this would mean adding more distance for flights and thereby more carbon dioxide emissions. Scientists at the University of Reading have concluded, however, that even if carbon dioxide emissions increase with rerouting, the overall effect on the climate will be less damaging in comparison to original flight paths.

Other solutions are more radical: reduce the cruising altitude for all jetliners by 2,500m to reduce contrail formation. However, this would increase air friction, forcing planes to burn more fuel and reduce the speed of aircraft.

In general there are legislative actions meant for reducing aircraft emissions, but decreasing the impact contrails have on the climate and weather is not one of them.

Sarthak Mani Sharma

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