What is invisible is more dangerous

Besides multiple street demonstrations that gridlocked Kathmandu’s traffic for the past weeks, public discourse in Nepal has also been dominated by dangerously high air pollution levels.

Caused mostly by hundreds of forest fires raging across the country, the smoke contains suspended soot particles that harms human health. Thursday’s rain have cleared the air somewhat, and many people will soon forget how bad the air quality was. But the time to address the roots of next summer’s fire season is now. 

The reason everyone was talking about air pollution was because the smoke from wildfires was visible. But much more toxic are the invisible and odourless gases from vehicular and industrial emissions which have always been there.

The theme of World Health Day on 7 April this week was ‘Healthy Beginnings, Hopeful Futures’ dedicated to preventing maternal and newborn deaths. It is estimated that in Nepal, 30% of neonatal mortality can be blamed on air pollution.

But that is only part of the story. Harmful as fine particulate matter is to human health, carbon monoxide, nitrogen dioxide, ground-level ozone and other gases in vehicular emissions are more hazardous to health.

While the concentration of suspended particulate matter tinier than 1.5 microns (PM2.5) is closely monitored, these toxic gases are invisible, not measured much, and the public is not aware about the dangers they pose.

Surface ozone is produced by the interaction of various gases found when burning fossil fuels. Besides being poisonous, ground level ozone contributes up to 0.23°C to global warming because it is also a greenhouse gas.

A new policy brief by the Clean Air Fund titled The Case for Action on Tropospheric Ozone blames surface ozone for a half a million premature deaths every year, 54.8% of which are in South Asia. Ozone also stunts plant growth and reduces crop yields by 26% globally, and 11% loss in forest productivity, the report adds. 

Read also: Bad air and polluted politics, Sonia Awale

Ground-level ozone is not emitted directly into the air like other gases, but is formed when oxides of nitrogen (NOx), carbon monoxide (CO) and volatile organic compounds (VOCs) released from automobile tailpipes or industry smokestacks react chemically with each other in the presence of sunlight. The main source of carbon monoxide in Kathmandu Valley are its 1.2 million two-wheelers.

“Usually the concentration of carbon monoxide is 200-500 parts per billion (ppb), this has increased up to 3,000 in Kathmandu. Meanwhile, ground-level ozone has gone from 70-80 ppb to 150 ppb,” says Ravi Sahu, regional air quality specialist with the Kathmandu-based International Centre for Integrated Mountain Development (ICIMOD). 

Sahu says rampant forest fires of the past weeks have also added to carbon monoxide and ozone in the air, not just the fine particles that make up the visible smoke. He adds, “There isn’t much awareness about ground-level ozone and carbon monoxide, we need to urgently look into it.”

A distinction must be made between good and bad ozone. Stratospheric ozone protects living beings from harmful ultraviolet (UV) radiation from the sun. 

Tropospheric ozone can again be separated into two types: ozone in the free atmosphere which is a greenhouse gas much more potent than carbon dioxide, and ground-level ozone which has adverse impacts on health and agriculture.

‘Cutting tropospheric ozone presents a unique challenge as it requires smart and fast action across multiple greenhouse gases and air pollutants, as well as multiple economic sectors,’ notes the Clean Air Fund's policy briefing. ‘It is a growing and neglected problem that needs an integrated approach on both a local and global level to tackle climate change and air pollution together.’

Dying young

There was a time when Nepal made it to international news bulletins only if there were fatalities on Mt Everest. Now, Kathmandu’s bad air frequently makes headlines all over the world.

This past week, the concentration of PM2.5 that harms human health was up to 40 times the WHO recommended guideline — adding to the poisonous gases already present from vehicle emissions.

The Department of Environment says 40% of the pollution in the past weeks was from wildfires sparked by nearly 6 months without substantial rain over central Nepal. Most of the rest is from vehicular and industrial emissions from Kathmandu itself and across the southern border.

NASA’s Fire Information and Resource Management System (FIRMS) which issues daily maps of fires, showed hundreds of blazes raging across Nepal on Wednesday, mainly in Chitwan, Parsa and along the East-West Highway. 

“If we look at the figures for the last few years, it is clear that wildfires have become the biggest source of air pollution, they are seasonal but have overtaken vehicular emissions,” says urban planner and environmentalist Bhushan Tuladhar.

“Forest fires, stubble burning, and open burning of garbage are the bigger problems now. Nepal, India, Bangladesh, and Pakistan are at risk every year, we shouldn’t further delay in finding solutions,” warned air quality expert Bhupendra Das during an event on air pollution organised on 7 March by the Nepal Forum of Environmental Journalists (NEFEJ). 

Indeed, studies have shown that in winter 60% of the air pollution over Kathmandu is transboundary from the south, and in November it is compounded by smoke from crop residue burning by farmers in India and Pakistan blown in by prevailing winds. Forest fires are a regular pre-monsoon occurrence in Nepal, often intentionally set by farmers and herders to stimulate new grass growth for livestock. Winter rains have failed for eight of the past ten years, and this means the fires often spread out of control.

The other reason for the increase in wildfires is the doubling of forest fires to 46% of the country’s area in the past 25 years. But this has happened simultaneously with outmigration, with some mountain districts losing 30% of their population between 2011-2021.

With less pressure on forests for fodder and firewood, the undergrowth of community forests is loaded with dry fuel just waiting for a spark. The bowl-shaped topography of Kathmandu, Pokhara and other valleys further concentrates pollutants as they are trapped by surrounding mountains.

But a year with a high number of wildfires is usually followed by a year or two with fewer incidents. For example: there were 6,537 fires in 2021 but the following year the number was down to 1,528. There were 5,216 fires last year, this year the number has already reached 1,800, and the trend is likely to be broken.

Heavy rains forecast for the coming days are expected to douse some of the fires and clean up the air. But the damage has been done: Kathmandu residents of all age groups this week crowded clinics and hospitals with burning eyes, itchy throats, difficulty breathing, headaches, and dizziness.

But in the longer term, soot particles that are tiny enough to jump the blood-air divide in lung capillaries do not just cause Chronic Obstructive Pulmonary Disease (COPD), asthma, but also cancers, heart attacks, strokes, birth defects and other chronic diseases.

The latest Air Quality Life Index (AQLI) report by the University of Chicago shows that the annual concentration of PM2.5 in Kathmandu’s air rose from 17.87µg/m3 in 1998 to 31.33µg/m3 in 2022. Air pollution has got worse by 75% in Kathmandu in 25 years.

During this time, air pollution has reduced the average life expectancy of Kathmandu’s residents by 3.5 years. According to the Health Effects Institute in Boston, dirty air is among the biggest public health concerns in Nepal killing over 42,100 a year.

The adverse impact of high levels of air pollution is not limited to public health, it is seriously affecting tourism. Operators in Pokhara this week said that there were many negative online posts by visitors unable to see the famous panorama of Machapuchre and the Annapurnas even from Sarangkot.

Aviation is also affected, as planes have to circle sometimes for hours burning a lot of fuel because of runway visibility being below minima at Kathmandu airport. The higher fuel cost is just passed down to customers, making air tickets in and out of Kathmandu some of the highest in the world.

Kathmandu, with a population of four million, has not implemented a concrete policy to curb toxic air despite having formulated various action plans and repeated commitments by the government to protect the environment and control air pollution.

The Department of Environment’s 2017 Air Quality Management Action Plan for Kathmandu put forward a policy to reduce air pollution caused by vehicles which was approved by the Cabinet, but has yet to be put to practice.

The action included the immediate implementation of the Euro 5 emission standard to reduce pollution emitted by vehicles. However, Nepal has not even been able to implement Euro 4 standards so far. India, meanwhile, has already moved forward with the implementation of the Euro 6 standards.

Says Ravi Sahu: “Air pollution in Nepal is not just about air pollution, it has ties to tourism, aviation, the economy so we must be prepared for annual conditions like forest fires, and this requires urgent interdisciplinary collaboration.”