Nube de polvo del Sahara: qué complicaciones de salud puede causar y qué recomendaciones hay para protegerse

En su habitual recorrido de miles de kilómetros desde el norte de África, las partículas de polvo del desierto del Sahara ya alcanzaron esta semana el sureste de México y varios países del Caribe.

Cada año, más de 100 millones de toneladas de polvo sahariano se levantan desde el desierto, según la Administración Nacional Oceánica y Atmosférica de EE.UU., y buena parte llega a Europa y América.

De acuerdo con Olga Mayol, experta del Instituto de Estudios de Ecosistemas Tropicales de la Universidad de Puerto Rico, la actual nube tiene las concentraciones más altas de partículas de polvo observadas en la región en el último medio siglo.

Y aunque es un fenómeno común, que incluso tiene efectos benéficos en ecosistemas como el del Amazonas, este año se ha sumado a las preocupaciones de salud por los problemas respiratorios relacionados al nuevo coronavirus SARS-CoV-2.

Al alcanzar el territorio mexicano, el líder de la estrategia del gobierno para la pandemia, Hugo López-Gatell, pidió el miércoles a la población del sureste del país tomar medidas de precaución.

“Las partículas tienen un tamaño de entre 2,5 y 10 micras, que son las partículas respirables. Entonces, pueden entrar por nariz y boca al momento de respirar y alojarse en la tráquea, en los bronquios o llegar incluso en menor tamaño las 2,5 hasta los terminales, los bronquios y los alveolos en los pulmones”, explicó el epidemiólogo.

Las nubes de polvo suelen afectar a las personas que ya padecen enfermedades respiratorias crónicas, como el asma, el enfisema o la bronquitis crónica, que son parte de la Enfermedad Pulmonar Obstructiva Crónica (EPOC).

Y estas personas son más vulnerables a sufrir complicaciones si se contagian del nuevo coronavirus.

Más que solo polvo
La Organización Mundial de la Salud (OMS) explica que el peligro de este fenómeno “radica en el contenido de bacterias, virus, esporas, hierro, mercurio y pesticidas que presenta el polvo”.

Y es que cuando los vientos en el desierto del norte de África levantan arena, recogen contaminantes al pasar por zonas deforestadas de la región, principalmente de los países subsaharianos.

“Estas tormentas cuando logran concentrarse y alcanzar áreas pobladas de Europa y América, pueden provocar la aparición de alergias y crisis asmáticas en muchas personas”, explica la OMS.

Las personas con problemas respiratorios o inmunodepresión, que a su vez son los más vulnerables al covid-19, suelen ser los más afectados.

“Muchas veces se refieren casos de ‘gripes’ persistentes o alergias sin causa aparente que pueden haber sido provocadas por el contacto con partículas de origen biológico presentes en estas brumas”, dice la OMS.

¿Qué se recomienda hacer?
Lo ideal es evitar la exposición prolongada al polvo sahariano, por lo que la recomendación general es mantenerse en casa cuando hay presencia de estas nubes.

Los mayores cuidados deben ser tomados por personas que tienen problemas del grupo EPOC, así como adultos mayores, mujeres embarazadas y niños, señala la OMS.

Recomienda usar protectores faciales, como mascarillas o un pañuelo de tela húmedo que cubra completamente la nariz y la boca.

“Si se tiene sensación de cuerpos extraños en los ojos, lávese con abundante agua. Es preferible utilizar agua potable, hervida o clorada. Lávese las manos antes de iniciar el procedimiento”, añade.

También es importante cubrir fuentes de agua (pozos, recipientes o estanques) para evitar la contaminación. Y humedecer el piso antes de barrer para evitar que el polvo vuelva a quedar suspendido.

Sahara desert dust storm moves into US

Dust lofted into the air by a few dust storms across Africa has made the 5,000-mile journey across the Atlantic, the Caribbean, the Gulf of Mexico — and it has now moved into the United States.

“The Saharan dust will overtake entire states,” CNN meteorologist Tyler Mauldin says. “Even southern Illinois and Ohio may get into the mix. That’s how far north it could get pulled up.”

An area of higher pressure over the Southeast will allow the Saharan dust layer to move into much of the Gulf Coast region over the next couple of days.

Forecast models show a lighter amount of dust moving into the Gulf Coast states on Thursday morning. This week’s more dense concentration, seen in images across the Caribbean, won’t move fully into the southern US until later today and into the weekend.

Portions of Texas, Louisiana, Alabama and Florida could see milky-looking skies and an enhanced sunset this evening.

“The main impacts of the Saharan dust will be hazy skies during the day, locally reduced visibility and degraded air quality,” the Weather Prediction Center said. “However, this will also make for some very colorful sunrises and sunsets with deeper oranges and reds compared to normal.”

By Friday and into Saturday, the dense plume will move across all of the southern US.

Through the weekend, a thinner amount of dust will advance across much of the eastern US. At the same time, a denser concentration will hang around the Southeast, mainly Alabama, Georgia, and Florida.

“Some of this dust will settle to ground level,” CNN meteorologist Chad Myers says. “People should monitor their local air quality and possibly limit outdoor exposure.”

This Saharan dust plume is historic
“The ongoing Saharan dust outbreak across the tropical Atlantic is by far the most extreme of the MODIS satellite record — our most detailed, continuous record of global dust back to 2002,” tweeted Atmospheric Scientist Michael Lowry.

“It is definitely historic,” Olga Mayol-Bracero, a researcher at the University of Puerto Rico, told CNN Weather. “We knew we were going to be in an extraordinary situation.”

Many of her colleagues across the Caribbean said they have not seen air quality conditions this bad in their entire careers, she said.

Aerosols, measured in PM10, at Mayol-Bracero’s research station in northeastern Puerto Rico, have never reached the levels they have seen the past few days. Records at this station go back 15 years.

The dust was so thick in Puerto Rico and across the Caribbean, it darkened the skies and reduced visibility to only a few miles.

The Saharan dust plume is nothing new. It is called the Saharan Air Layer or SAL by scientists who study it and its effects on hurricane development.

But scientists say this one is historic because of the dense concentration of dust.

“While it’s normal for Saharan dust to reach the US every hurricane season, this event is unprecedented in thickness and coverage,” Mauldin says.

“Usually by the time dust from the Sahara has traveled this far, much of it has been dispersed and/or deposited to the ocean so that typically this long-range transport to the Americas would involve much lower concentrations,” Claire Ryder, NERC Independent Research Fellow at the University of Reading, told CNN Weather.

How the Saharan dust plume got its start

The initial dust outbreak was driven by a few smaller storm systems over central and west Africa. Several of these thunderstorms caused downdrafts and large-scale haboobs, or dust storms, to develop. This led to a large amount of dust being uplifted into the atmosphere from the Sahara, Ryder said.

At the same time these smaller dust storms were happening, the African Easterly Jet — strong winds higher in the atmosphere which usually transport dust westward — was anomalously weak this June.

That means a more significant amount of dust than usual was able to accumulate just off the west coast of Africa. It then could be transported west in a very dense plume when the jet picked up speed again.

The Saharan dust layer has paused hurricane season
To a hurricane, the Saharan dust is nothing more than extremely dry air. And hurricanes hate dry air; they need a hot, humid, and calm environment.

“The dust is the visible part of the reduced tropical development potential area,” explains Myers. “It is the dry air and additional vertical wind shear along with the dust that are the driving factors in limiting tropical storm development.”

Vertical wind shear is the change of wind speed and direction with height. For a hurricane to form, it needs little to no wind shear and a very moist atmosphere.

As long as the Saharan dust is around, the National Hurricane Center is likely to be watching fewer areas in the tropics. By CNNWire