Capturing urban activities and environment across time scales: Object detection and time-series analysis of 6.8 million images in Accra, Ghana

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Journal Article - Urban Air Quality Management at Low Cost Using Micro Air Sensors: A Case Study from Accra, Ghana

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Journal Article - The status and politics of bicycling in the cities of low- and middle-income countries

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Op-Ed - Ghana Deploys Air Quality Network in Industrial Tema

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Journal Article - Urban Air Quality Management at Low Cost Using Micro Air Sensors: A Case Study from Accra, Ghana

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Journal Article - An empirical modelling of ambient NO and NO2 concentrations in Accra, Ghana

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Journal Article - The feasibility and acceptability of clean fuel use among rural households. A pilot study in Central Ghana

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Journal Article - Nitrogen oxides (NO and NO2) pollution in the Accra metropolis: Spatiotemporal patterns and the role of meteorology

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Journal Article - Health impacts of changes in travel patterns in Greater Accra Metropolitan Area, Ghana

Measuring Air Pollution in African Cities

When Jenny Linden, an air quality scientist, tried to measure the pollution in Burkina Faso’s capital city, one of her instruments clogged up. It was designed for road dust in Arizona, but the dust in Ouagadougou far exceeded the machine’s limit, and it had to be sent to the United States for repair.

The instrument “could not take the level of pollutants they had there,” recalled Dr. Linden, who took measurements in Ouagadougou between 2003 and 2007 and is now a research associate in urban climatology at the University of Mainz, in Germany. So intense was the dust, she added, that “you don’t have a cold but you have an irritated nose the whole time.”

Read the full article @ NY Times

Gridded Anthropogenic OC Emissions in 2030 in Africa

Air pollution in Asia and Europe has grabbed headlines. But as Dr. Linden’s experience suggests, the problem is pervasive across Africa as well. Africa is urbanizing quickly, and pollution from sources like vehicle exhaust, wood burning and dusty dirt roads has reached worrisome levels in many cities. Equally or more troubling is air pollution inside homes, caused by cooking with wood or other sooty fuels. But few nations outside South Africa have imposed regulations to address the problem, experts say.

Anthropogenic CO2 Emissions in Africa

 

“We do know that in Africa, there’s a very major problem with indoor air pollution,” said Dr. Carlos Dora, an official with the World Health Organization’s Department for Public Health and Environment. Data for outdoor air pollution in cities, he added, is less available and may not capture the scope of the problem.

A factory in Kenya Producing Improved Cookstoves for Africa

 

Dirty air can cause lung damage as well as heart disease, strokes and cancer. Last month the W.H.O. estimated that one in eight deaths worldwide resulted from air pollution. The organization found that air pollution in African homes contributed to nearly 600,000 deaths in 2012. Africa had the third highest level of deaths per capita from indoor air pollution of any region of the world, though it was still well behind areas of the western Pacific region (including China) and Southeast Asia.

Explosive Growth in Africa's Combustion Emissions

 

The W.H.O. figures for deaths per capita from outdoor air pollution in Africa are well below the world average, but the lack of data is a barrier. Pollution monitoring is minimal on a continent that is mostly focused on other problems. Instruments are expensive, and academics say they often struggle to get grants to study the problem. The W.H.O. assesses outdoor pollution in Africa by drawing from satellite data, inventories of pollution sources, air-current modeling and occasional ground monitors, Dr. Dora said. Continentwide data is stronger than that for individual countries, he added.

 

In Nairobi, the Kenyan capital, normal levels of fine dust (meaning particles less than 2.5 micrometers in diameter, about 1/30 of the width of a human hair and a significant health threat) are usually five times as high as those in Gothenburg, Sweden, according to Johan Boman, a professor of atmospheric science at the University of Gothenburg. The Nairobi pollution doubles near the central business district, he said, reflecting high pollution from vehicle exhaust.

“It’s certainly not as bad as what we see from China,” he said. “On the other hand, in China it’s very much seasonal,” whereas Nairobi, with its relatively stable climate, has less variation. A survey several years ago by the W.H.O. showed Gaborone, Botswana, as having the eighth-highest level of particulate pollution (particles of up to 10 micrometers in diameter) among a list of world cities. But the W.H.O. stresses that it is an incomplete list, since many cities did not provide data — including some of the most polluted.

Measuring and Characterizing Pollution in Accra

 

The outdoor pollution problem is growing, as more Africans move to cities. Ms. Linden, who did research in Burkina Faso until 2007, said that “the situation is likely worse now” because Ouagadougou’s population has swelled by more than 50 percent since then. Major outdoor sources of pollution include old vehicles; the burning of wood and trash; industrial activities; and even dust from dirt roads, a serious issue in Ouagadougou. In West Africa, a wind called the harmattan adds to the problem in the winter, coating the region in Saharan desert dust.

One recent study, published in the journal Environmental Research Letters, estimated that Africa could generate 20 percent to 30 percent of the world’s combustion-driven sulfur dioxide and nitrogen oxides by 2030, up from about 5 percent each in 2005. Other pollutants are growing too: Organic carbon from Africa could rise to over 50 percent of the world’s combustion output, from 20 percent, the study said. The authors did their calculations using estimates about fuel consumption, growth and other emissions factors, and warned of “a considerable increase in emissions from Africa” in the absence of regulations.

One of few countries to put regulations in place is South Africa, where ozone and tiny particles are particular worries. Air quality standards went into effect in 2009. Restrictions on particles will tighten in 2015 and 2016, according to Rebecca Garland, a senior researcher at the Council for Scientific and Industrial Research in Pretoria.

Air Pollution in Ouagadougou

 

Elsewhere, action is lacking as African nations grapple with other problems. Dr. Dora of the W.H.O. said that in countries like China, the pressure to stem pollution comes from businesses, and “from what I know, there’s still not that pressure from businesses in Africa,” he said. However, some leaders are aware of the issue and want to address it, he added.

Air Pollution in Kampala

 

One initiative that has gotten considerable attention is cleaner cookstoves. The current fuels, including wood, charcoal, animal dung and crop residues, create smoke and soot. The W.H.O. is releasing information soon about how various technologies can improve indoor air pollution. The concept of cleaner cookstoves has been getting high-profile attention; however, some experts caution that some of the new cookstoves may be focused less on reducing air emissions than on other benefits like increased energy efficiency and preventing forest degradation.

From Gridlock to Brain Damage in Lagos

 

“I don’t think anybody’s really demonstrated that they’re clean enough” to play a serious role in improving public health, said Darby Jack, an assistant professor at Columbia University’s Mailman School of Public Health.

Measuring and Characterizing Particulate Pollution in Accra, Ghana (ERL)

Cities in the developing world often suffer poor air quality, which can be hazardous to health, yet there have been relatively few studies. With that in mind, a team has assessed the particles causing air pollution in rich and poor neighbourhoods of Ghana’s capital Accra.

Link to the press release.
Link to the journal article in ERL.

"Sub-Saharan African cities are increasingly among the most polluted cities in the world," Zheng Zhou of Harvard School of Public Health, US, told environmentalresearchweb. "However, the availability of air pollution data in this region is limited. Most current studies have focused on the indoor environment in the rural area; substantially less work has been done in the urban area."




Accra, which had a population of 2.27 million in 2012, is one of Africa’s fastest growing cities. Zhou and colleagues from Brazil, the US, Ghana and the UK took particulate matter samples in four neighbourhoods of the capital between September 2007 and August 2008. The areas – James Town/Usher Town, Asylum Down, Nima and East Legon – lay on a straight line from the coast to Accra’s northern boundary.
James Town/Usher Town and Nima are densely populated, low-income areas where most people use biomass for cooking at home and for street food. Asylum Down is a middle-class area and East Legon is an upper-class district where most families live on large plots of land in modern low-rise homes, according to the researchers.

Study neighbourhoods and measurement sites. The polygons on the central panel show census enumeration areas (EAs). Each EA has approximately the same population; hence the area of an EA is inversely related to population density. EAs are categorized according to quintile in terms of per cent of household using biomass fuels. Each colour represents a different quintile. The sites were at locations that were typical of each neighbourhood's living environment, with the EL site being far from major traffic and the AD site being next to a road with moderate traffic. In NM we also had a second site next to a road with heavy traffic. The distances of measurement sites to the ocean coast were: JT 0.5 km, AD 3 km, NM 4.5 km, and EL 9 km.

Biomass combustion was responsible for between 10.6 and 21.3 µg/m³ of fine particle mass, contributing more in the poorest neighbourhood, the team found. Other particles came from sea salt, vehicle emissions, tire and brake wear, road dust, and burning of solid waste. As for biomass combustion, burning of solid waste was a greater source of pollution in poorer areas, where waste is collected less frequently. At the measurement stations near traffic routes, in Asylum Down and Nima, there were more road dust and traffic aerosols.
"We have seen large contributions from biomass burning to PM2.5 levels – particulate matter less than 2.5 micrometers in size – in urban Accra," said Zhou. "On average, biomass combustion contributed 40 to 50% of total PM2.5 mass outside the windy and dusty Harmattan period. Road dust and vehicle emission also accounted for 10 to 30% of total PM2.5 mass. We found that contributions from sea salt and crustal dust varied significantly by season."

Between December and January, the Harmattan, a dry and dusty West African trade wind, blows from the Sahara south towards the ocean in the Gulf of Guinea. "During peak Harmattan season, crustal dust was the largest contributor to PM, accounting for about 40% of total PM mass," said Zhou. The period saw about 10 times as much particle mass from crustal sources as usual, as well as an increase in resuspended road dust and particles from biomass burning.

"Our results show that urban air pollution in Accra is a complex mixture of both natural and anthropogenic sources," said Zhou. "Urban air quality in African cities can benefit from reducing dependence on solid fuels and improving road conditions. [This] requires policies related to energy, transportation and urban planning, and forestry and agriculture, with explicit attention paid to the impacts of each strategy in poor communities. Such cross-sectoral integration requires emphasis on the urban environment and urban poverty in the post-2015 development agenda."

For example, as the team writes in Environmental Research Letters (ERL), large-scale transitions to cleaner fuels such as liquefied petroleum gas (LPG) may require targeted subsidies for fuel, and financial assistance towards the initial cost of an LPG stove for poor households. "Perhaps more importantly, sustained use of clean fuels requires improving the energy delivery and distribution infrastructure so that people can have regular trouble-free access to fuel purchase, something currently not available in poor neighbourhoods," the researchers added.

There’s also a need for research on the acute and chronic health effects of exposure to crustal particles, the team believes, and whether air pollution regulations in developing countries should be based on total particle mass or specifically target combustion sources.

"We hope to pursue studies that quantify the health effects of air pollution in Accra, noting its different chemical composition and sources," said Zhou. "We would also like to continuously examine whether energy and environmental policies are influencing air pollution, either as improvement or deterioration."