Togo’s first long-term air pollution monitoring reveals levels
For the first time in years, researchers have monitored air pollution in the West African capital of Togo, Lome. preliminary result, post On March 10, the city regularly experienced unsafe air pollution levels. The study was led by researchers at Columbia University’s Lamont-Doherty Earth Observatory and the University of Lome.
Researchers from Columbia University and the University of Lome have installed five sensors in the city of Lome to monitor air pollution levels.
Globally, air pollution is the fourth leading risk factor for premature death. An estimated 6.67 million people died in 2019, including 1.1 million in Africa.
The new study focused on PM2.5, a form of air pollution made up of tiny, inhalable particles. In the body, these particles from vehicles, coal-fired power plants, waste incineration, and other human and natural sources can cause asthma, heart disease, lung cancer, and more.
However, PM2.5 levels and their corresponding effects on human health remain largely unmonitored and unstudied in many regions of the world. Efforts are largely focused on the United States and Europe.
To bridge this gap, researchers at the Columbia Climate Institute have launched a Urban Clean Air Toolbox Projects to identify and address the causes of urban air pollution India, sub-Saharan Africaand Indonesia. Research in Togo is part of this effort.
Air pollution data is scarce in many countries because a single monitor can cost hundreds of thousands of dollars and multiple monitors are needed to track levels across a city.
Clean Air Toolbox Researchers overcome this challenge By using low-cost PM2.5 sensors, each sensor costs only $250. Study co-author Daniel Westervelt of Columbia University installed five of these sensors in Lome in 2019, and they have been maintained by local colleagues since then.
While low-cost sensors collect high-quality data, “they’re not perfect,” said lead author Garima Raheja, a Columbia University doctoral student. “Sometimes they lose their Wi-Fi connection and we lose data until someone can get in and fix the sensors. But thanks to the tireless work of our collaborators and their students in Lome, we were able to maintain good air quality records and Collaborate to analyze data from it.”
Years of data show that the annual average of PM2.5 in Lome is four to five times higher than the latest World Health Organization guidelines, which stipulate that the annual average PM2.5 concentration should not exceed 5 micrograms per cubic meter.
Distribution of daily PM2.5 averages. On 87% of the days, PM2.5 levels exceeded the level recommended by the World Health Organization (dotted line).
Some of Lome’s air pollution comes from human activities. Sources include vehicle exhaust from nearby highways, dust from unpaved roads, waste combustion and cooking emissions.
PM2.5 pollution also has strong natural sources. Harmattan — dry, dusty winds from the Sahara between December and February — increased PM2.5 concentrations by 58 percent. However, daily and weekly trends in PM2.5 pollution are largely controlled by anthropogenic emissions.
From December to February, a dry wind called Harmattan brings dust from the Sahara Desert, greatly increasing Lome’s PM2.5 levels.Photo: Wahid Mellouki, National Center for Scientific Research
“These first measurements underscore the need to improve air quality in a rapidly growing urban metropolis,” the authors wrote in the paper. Lome’s 1.4 million residents are currently exposed to these unsafe air pollution levels, and the city is expected to have will grow in the next few years.
“While Harmattan is difficult to control, we can still reduce anthropogenic contributions to air pollution,” Raheja said. “I hope this work will help develop strong mitigation policies that will protect Lomé residents.”
Although Togo does not currently have its own air quality monitoring standards, it adopted a plan in 2020 to reduce air pollution and combat climate change. This research helps establish baseline air pollution levels so that future reductions can be quantified. “It’s hard to solve problems when you don’t know where to start,” Raheja noted.
The researchers plan to continue measuring PM2.5 levels in Lome and hope to expand their sensor network to better understand the distribution of air pollution in the growing city.
“Understanding air quality is the first step,” Raheja said. “Improving air quality can take a lot of work and years, but at the same time, an early warning system using air quality forecasts can help alert residents to days when air pollution is particularly severe.”
Co-authors of the study include: Kokou Sabi, Hèzouwè Sonla and Eric Kokou Gbedjangni of the University of Lome; Daniel Westervelt and Celeste McFarlane of Columbia University’s Lamont-Doherty Earth Observatory; and Collins Gameli Hodoli of the Clean Air One Atmosphere in Accra, Ghana.
