According to Legadima, what is being experienced is not necessarily a “sulphur smell” but the smell of hydrogen sulphide gas – which smells like rotten eggs – and is now being experienced due to air dispersion.
“In the last three weeks we’ve been having more rain, and the weather is changing. One of the factors that influence air pollution is wind speed, direction, pressure and the temperature,” said Legadima.
⚠️ ALERT: UNHEALTHY AIR QUALITY LEVEL FOR SENSITIVE GROUPS in GAUTENG WEDNESDAY, as SULPHUR STENCH CONTINUES!!!
????HIGH RISK GROUPS:
•Those with lung disease
•Those with heart disease
????Air quality levels considered ‘OK’ for healthy adults
— Gauteng Weather (@tWeatherSA) February 17, 2021
Where does it come from?
Those who have been experiencing the smell pointed at Mpumalanga power plants as the source of the smell that has caused headaches in some people.
While Legadima did not point to a certain direction, he mentioned refineries – especially petroleum refineries that use crude oil and arch furnaces where coal is used – as the culprits.
“It might come from chimneys where they burn hydrogen sulphide. We’ve been having more rain in the last three weeks so you might find that there are challenges from those refineries.”
According to Legadima, the province is experiencing what is called temperature inversion, where the cold air from the top of the atmosphere presses the warm air to ground level.
Once it presses the warm air to ground level, the gas from the chimneys does not go up, it goes straight and spreads on the ground level, hence people experience the smell.
Is it harmful?
Legadima said government was looking into making hydrogen sulphide a criteria pollutant, but it has not yet been declared as such because it does not necessarily make people sick.
“It’s a nuisance, but not necessarily harmful because the concentration is not as high,” said Legadima.
“It’s going to go away, because it is already in the atmosphere. Two elements have bonded together – hydrogen and sulphur. Sulphur has high electronegativity compared to hydrogen, it cannot be broken easily – even by the UV [ultraviolet] rays from the sun.
“Over some time, I can’t say tomorrow or in three weeks’ time because the weather is changing – it’s just a matter of weather conditions, it will go away because the weather is changing.”