Sahara dust – The good, the bad, and the unhealthy

HERE IN THE Caribbean, we are periodically inundated with Sahara dust. At such times, like recently, our vividly blue Caribbean skies are temporarily faded by the desert’s dust. The Sahara dust’s potential to impact the health of the residents in our region, while generally underappreciated, is significant.

Origins of the Sahara Dust Sahara dust is generated from the Sahara desert, the largest desert in the world, which is located in Northern Africa. High-velocity winds traversing the Sahara, especially its Bodélé Depression in northeastern Chad, generate these dust plumes which are capable of travelling westwardly for thousands of kilometres and reaching the Caribbean in just a few days. The Caribbean is more than 10,000 kilometres west of the Sahara.

While the peak months for the Caribbean to be affected by the Sahara Dust are May through September, however, in recent years we have been impacted at other times of the year.

It is estimated that over 180 million tons of Sahara dust, generated in pulses, traverse the Atlantic Ocean in any given year. As the Sahara’s dust plumes make their way over the Caribbean, its dust rains down in variable amounts on the countries and people of our region.

What is the Sahara Dust made up of?

The Sahara dust is made up of:

● Silicates

● Sulfates

● Quartz

● Calcium

● Soot

● Iron

● Phosphorous

● Carbon-rich particles

● Bacteria

● Fungi

● Viruses

The beneficial effects of the Sahara dust

The Sarah dust is not all bad news. It plays an important role in the biology and climate of our planet.

Such roles include, but are not limited to:

● It mitigates the intensity of hurricanes in the proximate two-thirds of the hurricane season. The presence of the Sahara dust high in the atmosphere over the Atlantic Ocean has a drying effect on the atmosphere, which in turn results in an unfavourable environment for the formation and strengthening of hurricanes.

● The iron and phosphorus in the dust transported to the Amazon basin serves as its main source of fertilizer. In the process it helps to sustain one of our planet’s primary carbon sinks, resulting in the sequestration of vast volumes of atmospheric carbon.

● The light-coloured Sahara dust acts to reflect some of the sun’s incoming rays and in the process has a mitigating effect on the atmosphere’s and ocean’s temperatures.

● The marine bacteria and phytoplankton in the Atlantic Ocean and Caribbean Sea are highly dependent on the Sahara dust for their iron supply.

These bacteria and phytoplankton are a major source of atmospheric oxygen.

The bad effects of Sahara dust

● While it is not settled what factors are specifically responsible for the sargassum blooms, however, several scientists are convinced that the reason could be multifactorial- inclusive of climate change, fertilizer run-off from and destruction of the Amazon, and the iron and phosphorous raining down from the Sahara dust.

● The “dirty rain” from the Sahara dust can become deposited on solar panels and reduce their efficiency.

● In June, 2020, the Sahara dust inundated the Canary Islands resulting in considerable disruption to air travel.

● Studies have linked some of the bacteria transported on the Sahara dust particles to coral reef damage in the Caribbean.

● On many occasions, the presence of Sahara dust in the atmosphere significantly reduces visibility.

● The sargassum blooms, dulling of our skies, the impact on our coral reefs, its negative health impact, and the disruption of air travel are a recipe for potentially compromising our tourism industry.

Sahara dust and our health Sahara dust is primarily made up of particulate matter (PM).The WHO estimates that 1.4% of all deaths worldwide are caused by PM.

The Sahara dust can affect anyone. However, those most vulnerable include:

● Babies and young children

● Elderly

● Asthmatics

● Those with COPD – i.e. emphysema and bronchitis

● Those prone to respiratory tract allergies The coarser particles are more likely to cause:

● Eye irritation

● Skin irritation The finer particles are more likely to cause:

● Respiratory tract irritation – Sneezing, runny and itchy nostrils, sinus congestion, itchy throat, post nasal drip, coughing.

● Increased susceptibility to upper respiratory tract infections, bronchitis, and pneumonia.

● Exacerbation of asthma attacks.

● Exacerbation of COPD.

● Increased incidence of cardiovascular deaths – e.g. heart attacks and strokes.

● Silicosis.

How to reduce the negative health impacts of the Sahara dust: