Publication: Sunday Sun
Paper Section And Page: 15A
Paper Date: Sun, Oct 7, 2001
Category: News
Byline: Terry Ally
HUGE African dust clouds don't only create haze in Barbados, they are also
responsible for triggering upper respiratory tract infections such as
asthma, runny noses, itchy eyes, and breathing difficulties. It is not the
actual dust that impacts the health of Barbadians but the bacteria and fungal
spores which travel with some dust clouds.
"It was previously thought that bacteria and fungi would be killed by ultraviolet radiation from the sun on its way across the Atlantic Ocean but my research has proven that to be incorrect. There is a link between the arrival of the dust with pathogens and an upsurge in upper respiratory tract infections in Barbados," Edmund Blades told the SUNDAY SUN.
Barbadians breathe about 14 litres of air per minute or about 20 cubic metres per day and in a dust-contaminated atmosphere Barbadians inhale between 200 to 7 500 spores per cubic meter of air which Blades said the immune system can easily handle but those with compromised systems or those susceptible to asthma or other respiratory illnesses or the elderly can become sick.
Blades, a (technologist) at the Queen Elizabeth Hospital, has been studying the impact of the dust on asthma in Barbados. He is the first author on two recently published papers on the subject. Other authors were Professor George Matthison of the University of the West Indies and Dr Raaina Naidu of the Accident and Emergency Department of the hospital. The first paper looked at the microbiological analysis of Sahara dust and its association with asthma in Barbados while the second focused on the impact of pollen and spores aeroallergens on asthma in Barbados.
Apart from proving the theory to be incorrect, Blades has identified the types of bacteria and fungus which comes over on the dust and what types of impact they can have on human health. Everyday Blades collects dust sample from the University of Miami's dust monitoring station at East Point in St Philip and cultures the samples to see whether bacteria or fungi would grow. If they appear, he identifies them and so far he has identified nine major groups of pathogens so as to determine what type of illnesses can arise from the inhalation of the bacteria or fungi.
"The largest group is mycelia sterilia or sterile fungus which we are unable to identify. The next largest group comprises several species of Aspergillus," he said.
Some bacteria and fungi may cause upper respiratory tract infections and others cause lower respiratory tract (lung) infections. People whose immune systems are compromises could die from the inhalation of these airborne pathogens. Blades discovered that not every dust cloud carry pathogens and that dust also from different parts of Africa, and carry different pathogens however more research is needed in this area, he said.
The dust monitoring station at East Point has been in operation since 1965 and is operated by Professor Joseph Prospero of the University of Miami who is the acknowledged expert on the air-transport of Saharan dust. His research has primarily focused on the chemical characteristics of the dust while Blades has looked at the biological characteristics.
Eugene Shinn of the United States Geological Survey has estimated that 500 million to one billion tonnes of dust travels across the Atlantic annually and it was recognised since the early decades that bacteria and spores could travel with the dust. The most graphic example was October 14 and 15, 1989 when large African desert locusts were transported in dust clouds to Trinidad, said Shinn. The years of the largest dust influx was between 1983 and 1987, he said.
In each year dust could travel mainly between April and October. Data at Barbados shows that the active dust transports started around the mid-1970s and started to fall off in the mid-1990s. This was because of prolonged drought in the Sub-Saharan (Sahel) region and correlates to the inactive cycle of the Atlantic hurricane seasons. Professor Bill Gray of the Colorado State University said that one of the things which drives Atlantic hurricanes was the level of rainfall in the Sahel. He said that dry periods correlate with suppressed hurricane activity and wet periods correlate to enhanced hurricane activity.
The professor of atmospheric sciences also said that between 1970 and 1990 there was a multi-decadenal cycle of low hurricane activity but this has reversed in the mid-1990s when he believes that the Atlantic has entered a new 30-year cycle of increased hurricane activity. If the correlation is in fact correct it means that asthmatics can breath easier in the next three decades.