Find out what exactly makes smoke black and why it is dangerous
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As a Durbanite, I am accustomed to clear blue sunny skies, dotted with white fluffy clouds, but last week, these beautiful skies were blocked out by billowing black smoke, signalling to those kilometres away that destruction lives here.
The thick, black smoke choked out our skies, sometimes blocking out the sun for as far as the eye can see.
The source of the dark clouds were the shopping malls, stores, warehouses and factories which were set alight by arsonists during last week’s looting and riots in KZN and Gauteng.
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Being an obvious environmental and health concern, I will try to explain what exactly makes smoke black and why it is dangerous.
According to Firefighter Insider, smoke is simply a by-product produced when a fuel burns but is not consumed in its entirety.
In a braai, for example, the smoke particles are what we might think of as “ash”.
It depends on the fire and the product being burned and how well it is being burned as to what kind of smoke may be produced.
Smoke is usually made up of tiny particles of either partially oxidised, fully oxidised or unreacted fuel particles. It can be poisonous if the particles contain toxic elements or compounds and its smoke is very dangerous in the event of a building fire, where it can cause suffocation even if there is no toxic element to it.
The majority of people who die in a fire die from smoke inhalation rather than being burned by the fire itself. This is because the smoke may contain numerous toxic chemicals from plastics and paints and because the smoke can displace the clean oxygen in and around the immediate vicinity, leaving little to breathe.
The mountains of black smoke we saw last week in KZN was an indicator of heavy fuel, synthetic chemicals or manmade materials on fire. These materials produced black smoke that is extremely toxic, laden with harmful chemicals. So, in general, the darker the smoke, the more dangerous it is.
Firefighter Insider further advises that white smoke tends to indicate that the fire is creating either gas or water vapour and it can mean that the fire has only just started burning or is in the process of going out. It may also mean that light materials are on fire such as hay or other dry plant fibres.
Grey smoke, in general, means that the fire has nearly run its course and it may be struggling to burn material effectively.
A 2014 study published by the European Commission Science for Environment Policy stated that increased black smoke pollution was associated with increased mortality rates almost a month after exposure.
“The researchers studied death rates in relation to pollution concentrations over a 22-year period in the city of Glasgow, UK, and found significantly higher mortality rates among residents at 13-18 and 19-24 days after increased exposure to black smoke.”
According to the Oregon Health Authority, “acute health effects that result from exposure to these types of fires include eye, nose and throat irritation, exacerbation of asthma and respiratory conditions and potential exacerbation of pre-existing heart disease”.
“The most serious health impacts from exposure to tyre fire smoke appears to be effects on those with pre-existing cardiovascular disease or respiratory conditions such as asthma.”
Acid rain could be an environmental concern as well. According to the United States Environmental Protection Agency “acid rain results when sulphur dioxide (SO2) and nitrogen oxides (NOX) are emitted into the atmosphere and transported by wind and air currents. The SO2 and NOX react with water, oxygen and other chemicals to form sulfuric and nitric acids. These then mix with water and other materials before falling to the ground. Acid rain damages crops and buildings, may kill wildlife and livestock without protection and contaminate freshwater sources.