<figure><img width="1125" height="1500" src="https://superdesk-pro-c.s3.amazonaws.com/sd-nepalitimes/2022111012110/636cd9bc9c7e80680e092ebajpeg.jpg" alt=""/><figcaption>Smoke from wildfires was thick enough to nearly block out the sun in Kathmandu. Photos: KUNDA DIXIT</figcaption></figure>Kathmandu Valley endured one of the worst air quality in recent years on Friday as wildfires fanned by strong winds scorched forests in the Himalayan foothills.<a style="font-size: 15px; letter-spacing: 0.01em;" href="https://firms2.modaps.eosdis.nasa.gov/map/#t:adv;d:2021-03-26;l:terra_crc;@85.9,28.0,8z" target="_blank" rel="noopener noreferrer">NASA Worldview satellite photograph</a> taken at 1300hrs on 26 March showed thick smoke being blown into Himalayan Valleys and across northern India.Most of Central Nepal has seen an unusually dry winter with only 15% of the normal precipitation in January and February, and this has left the slopes tinder dry. This is also the time of year when farmers burn crop residue and brush to make fields ready to sow maize. <figure><img width="1500" height="692" src="https://superdesk-pro-c.s3.amazonaws.com/sd-nepalitimes/2022111012110/636cd9bf9c7e80680e092ebbjpeg.jpg" alt=""><figcaption>Fire races through the undergrowth in a hardwood forest in Rautahat district on Friday afternoon, one of many big flare-ups that smothered Central Nepal in smoke on Friday. Photo: Mukesh Pokhrel</figcaption></figure><figure><img width="828" height="621" src="https://superdesk-pro-c.s3.amazonaws.com/sd-nepalitimes/2022111012110/636cd9c29c7e80680e092ebcjpeg.jpg" alt=""><figcaption>The AQI in Kathmandu at 1500hr on Friday was the worst in recent years: 632, which is nearly 20 times more hazardous than what WHO says is safe to breathe. </figcaption></figure>The <a href="https://www.nepalitimes.com/banner/dirty-politics-dirty-air/" target="_blank" rel="noopener noreferrer">Air Quality Index (AQI) in Kathmandu Valley</a> at 1500hrs was 632, which is nearly 20 times worse than what the World Health Organisation regards as being safe to breathe. Even in <a href="https://www.nepalitimes.com/banner/central-nepal-engulfed-in-smoke/" target="_blank" rel="noopener noreferrer">the most polluted afternoons</a> at this time of year, the AQI in Kathmandu’s city centre is below 150.Many people in Kathmandu complained of a burning sensation in the eyes and difficulty breathing as the Valley was shrouded in smoke that was thick enough to block the afternoon sun. <figure><img width="1297" height="788" src="https://superdesk-pro-c.s3.amazonaws.com/sd-nepalitimes/2022111012110/636cd9c49c7e80680e092ebdjpeg.jpg" alt=""><figcaption>A NASA Worldview satellite image taken at 1300hrs on Friday showed thick smoke being blown right across the foothills of the eastern Himalaya.</figcaption></figure><figure><img width="750" height="346" src="https://superdesk-pro-c.s3.amazonaws.com/sd-nepalitimes/2022111012110/636cd9c89c7e80680e092ebejpeg.jpg" alt=""><figcaption>Smoke blankets the East-West Highway near Chandranighapur in the Tarai on Friday evening. Photo: Mukesh Pokhrel</figcaption></figure>Most domestic flights to Kathmandu were cancelled after 1pm, and international flights were either cancelled or diverted because the visibility dropped below 800m.A Cathay Pacific flight from Hong Kong diverted to Delhi, while a Nepal Airlines flight from Delhi landed after holding for over an hour. A Himalaya Airlines flight from Dammam also had to divert. <figure><img width="720" height="480" src="https://superdesk-pro-c.s3.amazonaws.com/sd-nepalitimes/2022111012110/636cd9ca9c7e80680e092ebfjpeg.jpg" alt=""><figcaption></figcaption></figure><img width="640" height="427" src="https://superdesk-pro-c.s3.amazonaws.com/sd-nepalitimes/2022111012110/636cd9cc9c7e80680e092ec0jpeg.jpg" alt=""><img width="640" height="427" src="https://superdesk-pro-c.s3.amazonaws.com/sd-nepalitimes/2022111012110/636cd9ce9c7e80680e092ec1jpeg.jpg" alt=""><figure><img width="720" height="480" src="https://superdesk-pro-c.s3.amazonaws.com/sd-nepalitimes/2022111012110/636cd9d19c7e80680e092ec2jpeg.jpg" alt=""><figcaption></figcaption></figure><img width="640" height="427" src="https://superdesk-pro-c.s3.amazonaws.com/sd-nepalitimes/2022111012110/636cd9d39c7e80680e092ec3jpeg.jpg" alt=""><img width="640" height="427" src="https://superdesk-pro-c.s3.amazonaws.com/sd-nepalitimes/2022111012110/636cd9d69c7e80680e092ec4jpeg.jpg" alt=""><figure><img width="720" height="480" src="https://superdesk-pro-c.s3.amazonaws.com/sd-nepalitimes/2022111012110/636cd9d89c7e80680e092ec5jpeg.jpg" alt=""><figcaption>Photos: AMIT MACHAMASI</figcaption></figure>Adding to the smoke from the wildfire that has also been sand dust blowing from the Arabian and Indian deserts for the past week, and this is compounded by crossborder industrial pollution as well as Kathmandu’s own vehicular emission. The <a href="https://www.nepalitimes.com/banner/kangchenjunga-wildfire-visible-from-space/" target="_blank" rel="noopener noreferrer">wildfires are too extensive for Nepal’s meager fire-fighting capability</a>, and besides the blaze is in steep and inaccessible slopes and being spread rapidly by up-valley afternoon winds. <a href="https://www.nepalitimes.com/banner/wildfires-ravage-nepal-mountains/" target="_blank" style="font-size: 15px; letter-spacing: 0.01em;" rel="noopener noreferrer">Wildfires have been common this winter and spring</a> in Kaski and Dhading and Rasuwa districts in central Nepal burning for months. One fire in the forests of lower Manang burnt continuously from November to January.

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Wildfires in Nepal cause air quality to plummet

<figure><img src="https://superdesk-pro-c.s3.amazonaws.com/sd-nepalitimes/20221110111156/636cd9219c7e80680e092e81jpeg.jpg" alt="" width="1500" height="1000"/><figcaption>Haze shrouds Bhaktapur on Monday afternoon as smoke from fires in Chitwan engulfed Kathmandu Valley and Central Nepal. Photo: AMIT MACHAMASI</figcaption></figure>Kathmandu Valley and Central Nepal was engulfed in thick haze on Monday afternoon as prevailing winds whipped up fires in Chitwan and Parsa National Parks.Infrared satellite images from NASA’s <a href="https://firms.modaps.eosdis.nasa.gov/" target="_blank" rel="noopener noreferrer" data-saferedirecturl="https://www.google.com/url?q=https://firms.modaps.eosdis.nasa.gov&amp;source=gmail&amp;ust=1616508970355000&amp;usg=AFQjCNErMmof792DiNvE9DRev-Wskc40QQ">FIRMS (Fire Information for Resource Management System)</a> showed many fires raging at the eastern edge of Chitwan and across Parsa, in the vicinity of Hetauda, as well as in Bardia, Surkhet and other districts in the mid-mountains of western Nepal.<figure><img src="https://superdesk-pro-c.s3.amazonaws.com/sd-nepalitimes/20221110111156/636cd9249c7e80680e092e82jpeg.jpg" alt="" width="1000" height="539"><figcaption>Forest fires in Chitwan and Parsa National Parks southwest of Kathmandu in this infrared image from NASA’s FIRMS satellite taken on Monday. Image: FIRMS/NASA</figcaption></figure>Another satellite image in the visible spectrum from <a href="http://www.apple.com/uk" target="_blank" rel="noopener noreferrer" data-saferedirecturl="https://www.google.com/url?q=http://www.apple.com/uk&amp;source=gmail&amp;ust=1616508970355000&amp;usg=AFQjCNEbOVQv7FTp2t429z67KNcTUW51Iw">NASA Worldview </a>showed blue smoke shrouding Himalayan valleys of Central Nepal.<figure><img src="https://superdesk-pro-c.s3.amazonaws.com/sd-nepalitimes/20221110111156/636cd9279c7e80680e092e83jpeg.jpg" alt="" width="1000" height="689"><figcaption>Image in the visual spectrum taken by NASA’s Worldview satellite on Monday at 2pm local time. Image: NASA Worldview</figcaption></figure><figure><img src="https://superdesk-pro-c.s3.amazonaws.com/sd-nepalitimes/20221110111156/636cd9299c7e80680e092e84jpeg.jpg" alt="" width="300" height="401"><figcaption>Air Quality Index measured in Patan in Kathmandu Valley at 4pm on Monday showed a hazardous reading of 421, which is more than ten times higher than the WHO's safe threshold. Photo: KUNDA DIXIT</figcaption></figure>The national parks allow buffer zone villagers to enter the protected areas once a year in spring to collect deadwood and thatch grass. Villagers sometimes set fire to the grasslands, and prevailing winds spread these blazes.Deficient winter rain this year has made the forests in the Nepal Tarai drier than usual, which has led to the fires this year more extensive.Kathmandu Valley recorded an Air Quality Index (AQI) reading of 421 at 4pm on Sunday, which is more than 10 times higher than the threshold set by the World Health Organisation for air safe for breathing.In addition to the smoke, there was also pollution from traffic emissions, cross-border industrial smog from India, as well as wind-blown sand from the Arabian desert that has been covering the Subcontinent for the past week.

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Central Nepal engulfed in smoke

<figure><img src="https://superdesk-pro-c.s3.amazonaws.com/sd-nepalitimes/20221110111132/636cd3939c7e80680e08f975jpeg.jpg" alt="" width="2076" height="1210"/><figcaption>A NASA satellite image showing Central Nepal's river valleys and how they act as funnels for pollution from the Indian plains to travel up to the mountains.</figcaption></figure>The Himalayan mountains act as a barrier separating the clean air of the Tibetan Plateau from the polluted Indo-Gangetic plains. But Nepal’s rivers cut through the mountains, and their valleys allow smog from the plains to penetrate deep into the mountains.This haze intrusion goes up to elevations of 4,000m, and the pollution layer is more shallow and flat in winter, and inclined and parallel to the ridgeline in the pre-monsoon. The depth of this pollution layer up the valleys also decreases with elevation.<figure><img src="https://superdesk-pro-c.s3.amazonaws.com/sd-nepalitimes/20221110111132/636cd3969c7e80680e08f976jpeg.jpg" alt="" width="780" height="325"><figcaption> </figcaption></figure>These visible air pollution images are captured regularly by the <a href="https://modis.gsfc.nasa.gov/about/">MODIS</a> (Moderate Resolution Imaging Spectroradiometer) instrument aboard the two NASA satellites Terra and Aqua orbiting the Earth. The dull bluish haze is mostly made up of fine aerosol particles and extends right across the Indo-Gangetic plains from Pakistan to Bangladesh, as well as the Tarai in Nepal.While human-generated emissions from agricultural burning, urban, rural and industrial emissions are mainly responsible for this region-wide pollution, weather conditions and the blocking effect of the Siwalik Range also affect its spread. More interestingly, if we zoom in on the images, we can see that the haze does not just stay in the plains, but flows up into the inner Himalaya along river valleys.<figure><img src="https://superdesk-pro-c.s3.amazonaws.com/sd-nepalitimes/20221110111132/636cd3989c7e80680e08f977jpeg.jpg" alt="" width="780" height="381"><figcaption> </figcaption></figure>These satellite images provide valuable insight for researchers looking into the geographical spread and long-range transport of aerosol particles. Scientists at <a href="https://duke.edu/">Duke University</a> in the United States have developed a novel technique to use the high-resolution satellite images from MODIS and elevation data from <a href="https://www2.jpl.nasa.gov/srtm/mission.htm">SRTM</a> (Shuttle Radar Topography Mission) to extract the daytime haze run-up that measure intrusion length and height over the Arun Valley in eastern Nepal.The Arun River starts in Tibet, snakes around Mt Everest to find a gap between Makalu and Kangchenjunga to tumble down Himalayan gorges to meet up with the Sun Kosi and Tamor— flowing out into the Tarai at Chhatra and then through the Kosi Barrage to meet the Ganges in India. This also opens up the entry gate for haze to flow from the Indo-Gangetic Plains into the inner Himalayas.<figure><img src="https://superdesk-pro-c.s3.amazonaws.com/sd-nepalitimes/20221110111132/636cd39a9c7e80680e08f978jpeg.jpg" alt="" width="780" height="321"><figcaption> </figcaption></figure>In winter, the surface temperature in the plains plummets, and the air is dry. The southern edge of the Tibetan Plateau at upper levels is also battered by the sub-tropical jetstream, with weak westerly wind below it. The low surface temperature in the plains confines the pollution to a shallow <a href="https://glossary.ametsoc.org/wiki/Atmospheric_boundary_layer">boundary layer</a> that is lower than the Siwalik Range. Up-valley winds along the river valleys then transport the haze into the Inner Himalaya.The river valley-plains temperature contrast produces a pressure gradient that drives this flow up the valley during the day and down the valley during the night. Besides, the topography, vegetation cover and groundwater level in the slopes can also contribute to warming of valley air which could further amplify the up-valley wind.In addition, the daytime up-slope and night-time down-slope winds developing in the river valleys also play and important role in ventilating the air pollution from the valley surface.Measurements of the nature and size of fine aerosols were conducted for the first time in the middle Himalayan region in the pre-monsoon. In general, the aerosol size distribution peaks around 100nm, which is usually the oldest, most processed background aerosol and about the size of the Covid-19 virus.Another smaller peak around 20 nm, is indicative of fresh but not necessarily local aerosols. The chemical composition of PM2.5 (particulate matter below 2.5 microns) is dominated by organic matter. Organic carbon (OC) comprises the major fraction (64–68%) of the aerosol concentration followed by ionic species (24–26%), Elemental Carbon (EC) compromises 7–10% of the total composition and 27% of OC is water soluble.Elemental Carbon and Organic Carbon together are aerosols contributed by burning of wood fuels, crop-residue, coal including vehicular emission and others. The light absorbing properties of elemental carbon play a crucial role in atmospheric warming and surface cooling due to their interaction with the daytime solar heating.Industrial and vehicular emissions, biomass burning, soil dust and others including chemical transformations in the atmosphere contribute to the ionic species in aerosols. These are readily water-soluble parts of the aerosol which along with organic particles aid in their growth in presence of moisture, contributing to increase in optical thickness of haze.The aerosol concentration also changes over the day. It increases in the morning (05:00-10:00) and in the evening (17:00-22:00). The lower values in the afternoon could be attributed partly to more mixing, and increase in the boundary layer height.During the night, the downslope winds lift the warm air mass in the valley, resulting in the decrease of the aerosol concentration near the surface. On the other hand, aerosol loading can also be eventually washed away by local rainfall during the pre-monsoon and winter.<figure><img src="https://superdesk-pro-c.s3.amazonaws.com/sd-nepalitimes/20221110111132/636cd39c9c7e80680e08f979jpeg.jpg" alt="" width="780" height="300"><figcaption> </figcaption></figure>While pollution haze is visible even in satellite images, its quantitative measurements can also be made by remote sensing. Haze and dust particles in the air block sunlight reaching the ground by absorbing and scattering it. This property of aerosols is used to estimate the Aerosol Optical Depth (AOD).A long-term average of winter AOD from December-February over the last 20 years in the region shows that winter haze extends throughout the Indo-Gangetic plains, with relatively higher readings for the eastern regions of Bihar, West Bengal and Bangladesh, across Nepal’s southeastern border. The regional average winter AOD also shows an alarming increase in the past two decades due to increase in emissions from increased crop-residue burning, rapid urbanisation, industrialisation, etc.<figure><img src="https://superdesk-pro-c.s3.amazonaws.com/sd-nepalitimes/20221110111132/636cd39e9c7e80680e08f97ajpeg.jpg" alt="" width="780" height="481"><figcaption> </figcaption></figure>Aside from transboundary haze, this winter has also seen an increase in wildfires that have exacerbated the pollution in Nepal’s Inner Himalayan valleys. The Pathivara and Annapurna Conservation Area fires in December, followed by uncontrolled wildfires in Manang, Lamjung and Rasuwa in January were clearly visible in NASA satellite images.The very high pollution levels in Kathmandu Valley on 6-7 January was also aggravated by overcast skies which subdued the ventilation mechanism of the valley, but smoke from these wildfires also acted as contributors. Since the daily satellite data is in the public domain, they could be used along with global models by Nepal’s met office to nowcast air pollution episodes over the Himalaya.While local air pollution can be brought under control in the interest of protecting public health by the local governments with appropriate policy and regulation, it is trans-boundary pollution that cannot be easily addressed. It requires regional collaboration to adopt and implement policies to reduce sources of pollution like crop residue burning, vehicular and industrial emissions. The atmospheric initiative at the Kathmandu-based International Centre for Integrated Mountain Development (ICIMOD) could be one such mechanism.More immediately, there is an urgent need to set up permanent air quality monitoring stations along Nepal’s major river valley outlets to monitor trans-boundary air pollution and more research by universities in Nepal to improve our knowledge of local and regional pollution so that policy makers can make better decisions.Prabhakar Shrestha is a research scientist working at Bonn University, Germany.<img src="https://superdesk-pro-c.s3.amazonaws.com/sd-nepalitimes/20221110111132/636cd3a19c7e80680e08f97bjpeg.jpg" alt="" width="89" height="103">

How transboundary haze affects Nepal

<img width="1400" height="919" src="https://superdesk-pro-c.s3.amazonaws.com/sd-nepalitimes/20221107171136/636934909c7e80680e03e002jpeg.jpg" alt=""/>NEW DELHI – A diplomat friend returning home after less than three years’ service in India, was asked at his exit medical examination how many packs a day he smoked. When he protested that he was a staunch non-smoker, the doctor commented that x-rays of his <a href="https://archive.nepalitimes.com/article/Nepali-Times-Buzz/lung-diseases-in-south-asia,1112" target="_blank" rel="noopener">lungs </a>showed otherwise. All he had done was breathe Delhi’s air, three smoggy winters in a row.It really is <a href="https://www.nepalitimes.com/here-now/open-air/" target="_blank" rel="noopener">that bad</a>. When November comes, New Delhi begins to choke on a thick blanket of smog that chokes lungs, corrodes throats, and impairs visibility. It’s not just Delhi’s notorious diesel fumes from car and truck exhausts. There are also factories spewing smoke, charcoal braziers on the sidewalks, coal stoves used by roadside vendors, and agricultural stubble burned by farmers in Punjab and Haryana. Delhi had just three ‘clean air days’ in the whole of 2017. The worst air quality is in winter, when polluted air meets winter fog and is trapped. Poor air quality is now costing India at least 1% of GDP every year in respiratory diseases, reduced productivity, and increased hospitalization, and may be reducing Indians’ lifespans by three years. According to the State of Global Air report published by the Health Effects Institute, the absolute number of ozone-related deaths in India rose by a staggering 150% from 1990 to 2015. The economic implications of deteriorating air quality are equally ominous. Welfare costs and lost labor income due to air pollution amounts to nearly 8.5% of India’s GDP. Moreover, a recent study revealed that India’s toxic air is also dissuading executives from accepting assignments in Delhi: people are turning down lucrative jobs in order to save their lungs. In 2015, the New York Times’ former South Asia correspondent, Gardiner Harris, explained that he was leaving his post prematurely because merely living in Delhi was damaging his children’s <a href="https://www.nepalitimes.com/editorial/poor-health/" target="_blank" rel="noopener">health</a>. Harris wrote that Delhi is ‘suffering from a dire pediatric respiratory crisis in which nearly half of the city’s 4.4 million schoolchildren have irreversible lung damage from the poisonous air’. So he picked up his kids and left India.Most Indians don’t have that choice. They must live with respirable suspended particulate matter that becomes lodged in the lungs and impairs breathing. A study of Delhi schoolchildren between four and 17 years of age found that key indicators of respiratory health and lung function were 2-4 times worse than in schoolchildren elsewhere. And the damage was irreversible.India needs to make improving air quality a national priority. It needs to create state and national action plans for <a href="https://www.nepalitimes.com/here-now/cleaner-air-with-greener-buses/" target="_blank" rel="noopener">clean air</a>; set tough new targets for thermal power plant emissions, factory chimneys, and automobile exhausts; and establish a proper air pollution monitoring system. And it needs to act fast. Already, 13 of the world’s 20 most polluted cities and towns are in India. More than a million Indians are dying every year because of bad air. © Project SyndicateShashi Tharoor, a former UN under-secretary-general and former Indian Minister of State for External Affairs, and author of Pax Indica: India and the World of the 21st Century.Read also: <a href="https://www.nepalitimes.com/banner/poisoning-the-air-we-breathe/" target="_blank" rel="noopener">Poisoning the air we breathe</a>, Sonia Awale

Delhi’s deadly air

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