What is a mosquito coil?
“Mosquito coils contain a mix of substances. Along with the products that deter mosquito biting, there are also products that hold the coil together and enable it to smoulder slowly,” writes Cameron Webb, Clinical Lecturer and Principal Hospital Scientist, University of Sydney.
Additionally, there are two types of coils.
“Those that contain insecticides will kill (or at least “knock down”) mosquitoes, while those that contain aromatic substances (such as citronella) will repel mosquitoes or reduce the likelihood they’ll bite,” he adds.
Do mosquito coils prevent disease?
However, when a disease, such as malaria is concerned, reducing the number of bites isn’t enough.
“When there is a risk of disease, you need to stop all mosquito bites,” said Webb.
Referencing a review of previously published studies, Webb says there’s no evidence burning insecticide-containing mosquito coils prevented malaria.
The other growing concern with mosquito coils is the health risk involved from being around the smoke emitted from a coil.
Webb cites a study that estimated “the particulate matter produced from burning one mosquito coil was equivalent to burning 75-137 cigarettes.”
“This amount of exposure poses a health risk but there is a lack of clear evidence that the long-term exposure to mosquito coil smoke increases the risk of more serious health impacts, such as lung cancer,” he wrote.
“In the face of this uncertainty, the key message should be to avoid prolonged exposure, especially in enclosed spaces.”
So what is the best way to repel mosquitoes?
"There’s enough evidence to show that when used outdoors, burning a mosquito coil will assist in reducing mosquito bites, but should be used judiciously," Webb writes. Using them in combination with topical insect repellents probably provides the best protection."