Everything you need to know about Saharan dust
A view of Havana's harbour as dust carried by winds from the Sahara desert shrouds the city, Cuba June 25, 2020. (REUTERS/Alexandre Meneghini)
The dust-choked sky over southern Mauritania left no hint of the blue sky far above the region. The turbulent weather descending on the area that day had kicked up sand and dust, sending it rolling toward one of the nearby towns. People in the streets shielded their eyes and retreated indoors, a few jumping into their cars not a moment too soon.
A hazy red twilight took over the area as the dust thickened, car headlights soon becoming the only source of light. Within just a few seconds, day had turned into night. The wet season had begun, bringing with it one of the two dust seasons that the West African nation, along with others in the region, face annually.
Before the Saharan Air Layer (SAL) had reached the Caribbean Sea earlier this week, thermal lows near the West African coast churned up dust that would contribute to the traveling plume, but not before hitting West African cities and towns.
Penn State University Professor Gregory Jenkins, who holds a doctorate in meteorology, received a call from a friend in Senegal on June 19, 2020, along with a video showing day turning to night in southern Mauritania.
"Is this going to hit us in Dakar?"
Satellite imagery over Senegal on June 19, 2020, when a dust storm turned day to night. (NOAA/Aqua)
Calls and messages over WhatsApp ahead of dust storms are common for Jenkins, usually consisting of people trying to learn what the dust season could hold in store for them, Jenkins told AccuWeather in a Zoom interview.
"They were scared," he said of the people who had called him and sent the video.
"I've been caught in those (dust storms) before and it -- there's nothing good about being there except you feel afraid," Jenkins said. "You don't know what's happening and the sky looks dark. You can't tell. It's like, is this like a squall line of thunderstorms coming up, and then the wind just lifts up so quickly. Everything's blowing at you, and it just goes dark."
Dust from events like these in West Africa become embedded in the SAL, according to Jenkins. He shared another image from southern Mauritania on June 19, showing a town sitting right in the path of a towering haboob, a massive wall of dust lofted into the air by strong winds. A different image from about 10 days ago showed a filter of dust giving Podor, a city in northern Senegal, a hazy orange appearance.
Satellite imagery of Senegal on June 6, 2020, when a dust event over Podor created a hazy orange filter over the area. (NOAA/Terra)
"In northern Senegal, we've had several serious events over the last two or three weeks. They're like this kind of event prior to it going out over the Atlantic," Jenkins said.
Senegal sits right under Mauritania on the western coast of Africa. To the east of Mauritania is Mali, and Algeria, the Western Sahara and Morocco are to the north of the border. Jenkins and a team of researchers collected dust samples in Dakar, the capital city of Senegal, from 2013 to 2016, resulting in the research article Characterizations of Bacteria on Aerosols From Dust Events in Dakar, Senegal, West Africa, published on GeoHealth.
The team found bacteria that are linked with respiratory diseases, including Micrococcus, Burkholderia and Pseudomonas in the dust they collected. The article states additional analysis using genomic techniques would better assist in identifying bacteria and potential pathogens carried by the dust, which could cause health impacts in West Africa and, downstream of the SAL, the Caribbean, the Gulf Coast, South America and Europe.
Jenkin's concern, however, centers on the preparation and warning system for these dust events, which consists of monitoring satellite images and running models in the absence of ground measurements.
"Probably for the most of West Africa, hundreds of millions of people have no idea what the current conditions are as it relates to dust or any other types of pollution," Jenkins said. "But those dust storms are big, and they do impact tens of millions of people on the ground of Africa."
Property damage and even fatalities have even been associated with the dusty conditions and violent winds as big thermal lows move out over the Atlantic. To add to this concern, Jenkins believes it could be "quite plausible" that pathogenic bacteria on the dust could be driving most of the acute respiratory infections seen across Senegal from an earlier study he had co-authored.
Every year, around 2 billion tons of dust enters the atmosphere, globally, according to the World Meteorological Organization (WMO), leading to sand and dust storms that can affect the weather, the environment and people's health. Among the health concerns that the dust can bring are respiratory problems and heart disorders. Dust storms can also spread diseases such as meningitis, according to the WMO.
"We're extremely nervous because during the wet season, which begins in most places between April and say, July, flu cases always go up. So people's immune systems are going to be compromised," Jenkins said. "But in addition, that's the time of year we start to see malaria," he continued, adding waterborne diseases also become an issue at this time of year. "It's a very uncertain next few months in West Africa."
The "new dust" comes with the other dust season that rolls around in West Africa, typically around January. This summer dust season, however, comes with the concern of the coronavirus pandemic.
"Dust is going to be transferred down to the Atlantic for the next two months," Jenkins said. The only difference (from past SAL) is we have a pandemic, which makes it more worrisome like somehow all these factors can play a role in people's health."
Penn State University meteorology professor Gregory S. Jenkins discussing Saharan dust with AccuWeather over a Zoom call this week. (AccuWeather)
Past research has investigated if the coronavirus could spread via pollution particles such as NO2 and particulate matter, including dust. While there has been no conclusive answer, Jenkins points out that high levels of these pollutants, being linked to cerebral vascular disease and respiratory disease, could contribute to the mortality rate. Even more concerning, levels of dust in West Africa after these dust storms could remain high in the environment unless rain washes it away.
A look at the air quality in Dakar, Senegal, provided by Plume Labs showed that conditions were "unhealthy” and air quality in Podor, Senegal, “very unhealthy” on Wednesday. AccuWeather and Plume Labs have a partnership that allows users to monitor the realtime air quality in a given location from the AccuWeather website or mobile app.
"It's like a one-two whammy that we could be dealing with, and we really have to monitor carefully all the potential environmental variables that could be playing a role in COVID mortality, but also we don't know if it's spreading," Jenkins said. "If that was the case, that would be dangerous because ... some COVID virus hitches a ride on Saharan dust, it not only goes around West Africa, but it travels down to Brazil, it travels over to the Caribbean and the Southeast U.S."
The sky over Havana, Cuba, was brown on June 25, as dust from the Sahara Desert in Africa settled over the city.
While this variable is still uncertain, Jenkins said, he advises people to have a heightened level of awareness when a dust plume is overhead.
"Not only are asthmatics going to suffer more, but if there are pathogens on that dust," Jenkins said, "the number of respiratory infections could go up, potentially weakening people's immunity to (the) severity of COVID, so you just have to be on alert. I mean all across the Atlantic as it relates to dust at this point."
Strong winds had lofted dust particles "quite high up" to an altitude of 5 to 6 kilometers, or just under 4 miles, above the surface by Thursday before the cloud reached the Gulf Coast, according to Tyler Knowlton, director of communications, communities and partnerships at Plume Labs. "This particulate matter will tend to drop down over time, but usually due to heavy rainstorms, so it’s not something that people will be inhaling."
A thick orange haze hung over Podor, Senegal, June 6, 2020. (image/Mamadou Drame)
But could bacteria and the virus survive a trip across the Atlantic? Jenkins says the bacteria could -- it just needs to be activated from its dormant state. That activator could be taking residence in a body or the first rainfall of the season.
During the dry season, the bacteria will remain dormant, according to Jenkins, but then "wake up" at the first rain of the season. Once activated, Jenkins said, the bacteria will excrete a chemical compound that is another air pollutant -- as well as a potential ride for the coronavirus. Because of the activated bacteria, pollution levels in places like Senegal spike when it first rains, Jenkins said.
"The summer events are very unpredictable," Jenkins said. "They tend to be intense, and they may not last that long, but that suspended material is probably going to hang around for a minute. So we know less about that one."
However, Jenkins' recent measurements in northern Senegal indicate dust remaining at high levels afterward, with no rain to wash the dust from the environment. For him, there's a personal connection to the work he's doing.
"My ancestors came from West Africa. I've worked there on the ground. I see the level of poverty, and for me, it's not just crunching numbers or running models, it's actually serving a higher goal of helping those who have less," Jenkins said. "I don't feel there's any reason why a child should die from respiratory disease if there are ways to avoid that. We don't want that for our children. If there are ways that we can help, we do it."
This year, of course, there's been an added layer of worry due to the pandemic. Concern has grown over the dust lingering in the air for an extended period of time and how that could further impact health conditions and possibly play a role in worsening COVID-19 symptoms.
Living in a crowded, polluted city brings a higher risk of dying from a respiratory and cardiovascular disease, Jenkins said. But with exposure to dust in the air for an extended period of time on top of exposure to COVID-19, there's uncertainty in how drastically the factors could stack up against someone. As for people in more rural areas, Jenkins said they may never get to a hospital and pass away at home.
"It could be very tragic what we are seeing in Africa in the months ahead, and probably until we have a vaccine," Jenkins said. "We have to pay attention to vulnerable populations and how the environment might actually make it worse for them during this pandemic, and we have to be vigilant until there is a vaccine because we just don't know it is coming."
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