Harmattan and the air we breathe: What can we learn?

The massive climate change-induced dust fall event in west Africa has many lessons for all combating deadly air pollution  

By Anumita Roychowdhury
Published: Saturday 29 February 2020
Dust over Abuja, Nigeria in the morning. Photo: Anumita Roychowdhury / CSE
Dust over Abuja, Nigeria in the morning. Photo: Anumita Roychowdhury / CSE Dust over Abuja, Nigeria in the morning. Photo: Anumita Roychowdhury / CSE

I have never seen anything like this before. A dusty environment is not alien to me. And yet, seeing this thick overhang of brown dust over the city of Abuja and much beyond — covering nearly the whole of Nigeria, was scary.

Everyone is waiting for the rains. This annual invasion of the infamous Harmattan is a seasonal sheen of fine dust from the Sahara desert and dry and degraded land that blows over West Africa and deeply affects Nigeria during the dry months.

This seasonal ambush is expected to get worse with climate change and further degrade air quality. This cannot be doused with water sprinklers and road sweepers but needs a war against desertification and land degradation.

In the blurred horizon of Abuja, I could barely see the hills and rocks. Dust has blocked the sun and visibility. Sometimes, flights cannot land; on-road collision has become common; people are changing timings to venture out.

These are difficult times between November and March when dry, dusty, northeasterly trade winds (also called Harmattan) blow from the Sahara and the dry and degraded lands (the Sahel) over the West African sub-region and lift fine dust particles. Harmattan dust is said to be so dense that it reduces radiation from the sun and warmth and further lowers temperatures during colder dry months.

We hear so much about seasonal bush and forest fires in Australia and California, but rarely ever about the extreme events like Harmattan or dust invasion and its consequences for the poorer world.

The Nigeria media is issuing warnings from doctors about the harm and precautions. People blame this on nature and look helpless. There is no escape. The 2016 edition of Environment Health Insight shows that in west Africa, morbidity rates from desert dust (which is worse during the Harmattan) are higher than other areas.

Saharan dust outbreaks increase daily mortality by 8.4 per cent and cardiovascular effects dominate. The eyes and skin are affected and outbreaks of meningitis in the dusty environment are serious. This dust becomes lethal as it gets mixed with toxins from stoves using solid fuels, emissions from old vehicles and industry and open burning of waste and bush fires for farming.

The State of Global Air, 2018, has already alerted that Nigeria has the highest population-weighted annual average PM2.5 concentrations among the top regions of the world. It has third highest premature pollution related deaths in the world and highest in Africa. Air pollution is the second-largest killer in Africa. How does this seasonal event further complicate its health challenge?

Local perception is that this fury of nature is worsening. Literature confirms that Harmattan is getting more severe, more unpredictable and more loaded with dust. This hugely impacts the vulnerable poor people who live in drylands. Several African countries, including South Africa and Senegal, now monitor dust fall with a dust fall deposit gauge that collects dust and measures the dust fall rate.

What must happen?

Combatting dust at a regional scale is not going to be easy in the developing world. According to the 2016 report of United Nations Environment Programme, global annual dust emissions have increased by 25 per cent to 50 per cent over the last century due to land use and climate changes.

This needs more direct linking of air pollution mitigation with combating desertification and land degradation.

Harmattan needs action not only where the dust is blowing but also where it is originating. This requires a multi-government agenda on techniques about stabilisation of sand dunes, controls on wind erosion in cropland, crop management practices, soil management techniques, protective barriers, and extensive green walls of forest and plantation.

This policy action has started in Africa, largely spurred by the United Nations Convention to Combat Desertification. But the solution will have to be built to scale for integrated landscape management of cropland, grassland, dune fields, mines and building sites.

Plant dunes with adapted grasses, shrubs or trees, and establish vegetation cover for long term stabilsation. Sensitise farmers about minimum tillage, stubble mulching, zero-tillage to keep soil covered with plant residues.

There is growing demand in Nigeria for good climate and weather information, forecast systems and public warnings, especially for those who are in the path of the dust.

India must learn too

Summer is around the corner. Northern India’s dust season is arriving. Dust from human-influenced desertification, wind erosion from the Thar desert in Rajasthan is a significant dust source with large local impacts in Delhi and the National Capital Region (NCR).

A source apportionment and inventory study of the Indian Institute of Technology, Kanpur (IITK) in 2015 showed that crustal dust accounts for about 40 per cent of the total particulate matter in summer.

Countless dust particles in the air offer a huge surface area for other deadly toxic substances from vehicles, industry, solid waste and biomass burning, to cling on and enter deep inside our lungs. With increased desertification, enormous soil erosion, inappropriate agricultural practices and rise in global temperature, dust storm events will become more intense as the last few summers have shown.

While multi-sector air pollution control measures need to gather speed in India, the National Clean Air Programme has to converge with India’s commitment to the United Nations Convention to Combat Desertification to modify the effect of extreme weather events on air quality.

Globally, along with land stabilisation methods, African countries are building Great Green Walls like the 4,000-mile wall of trees stretching from Senegal to Djibouti or a 545 km-long curtain of vegetation in Senegal. Closer home, China has launched the Three Norths Forest Shelterbelt programme called the Great Green Wall, the Beijing–Tianjin Sand Source Control programme, and large-scale ecological restoration programmes to control dust.

Yet, northern India remains callous and indifferent to the dangerous erosion of forests and soil. Delhi and NCR are fighting one of the toughest battles against air pollution while allowing mindless destruction of the Aravallis — its only defense against desert dust and dust fall from degraded land and sources of oxygen.  We cannot bear to breathe so much dust also when toxic emissions from our vehicles and industry are rising. We will have to fight our own Harmattan too.

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