Mosquito coils are commonly used in homes to reduce mosquito activity, particularly during the evening and night. But while they may help repel mosquitoes, burning them also produces smoke that can contribute to indoor air pollution.
Scientific studies have detected fine particulate matter and several gaseous pollutants in mosquito-coil emissions. The concern becomes greater when a coil is burned for extended periods in a poorly ventilated room.
Why Does Mosquito Coil Smoke Matter?
A mosquito coil does not simply release its insect-repelling ingredient. It slowly smoulders, and the combustion of its other materials generates smoke and airborne particles.
Research examining mosquito-coil emissions has identified PM2.5, volatile organic compounds, aldehydes and polycyclic aromatic hydrocarbons (PAHs) among the substances that can be released. The exact emissions can vary depending on the product and its ingredients.
Because fine particles can be inhaled deep into the respiratory system, repeated exposure to polluted indoor air is a concern.
Closed Rooms Can Increase Exposure
Ventilation makes an important difference.
Studies measuring mosquito-coil emissions have found higher concentrations of pollutants when coils are burned under poorly ventilated conditions. One investigation found substantially higher carbon-monoxide concentrations in closed rooms compared with ventilated conditions.
This is particularly relevant when people spend several hours in the same room while a coil continues to burn.
What Can the Smoke Do to the Respiratory System?
Smoke and fine particles can irritate the eyes and airways. People who are sensitive to smoke or already have respiratory problems may experience greater discomfort when exposed to polluted indoor air.
The available evidence does not mean that every person who uses a mosquito coil will develop a disease. Risk depends on factors such as the product, duration of exposure, room size, ventilation and individual susceptibility.
However, prolonged exposure to indoor particulate pollution is an avoidable concern, making ventilation and alternative mosquito-control methods worth considering.
What About Children and Other Sensitive Groups?
Children can be more vulnerable to the effects of indoor air pollution because their respiratory systems are still developing. People with existing respiratory conditions may also be more sensitive to smoke.
WHO educational material identifies mosquito-coil burning as a source of indoor pollution and notes that smoke from coils can worsen indoor air quality.
For households where children or people with respiratory problems are present, reducing unnecessary exposure to smoke is therefore a sensible precaution.
How Much Pollution Can a Coil Produce?
Older laboratory research has shown that some mosquito coils can generate substantial quantities of fine particles. One widely cited study found that, under its specific experimental conditions, the PM2.5 mass emitted by one tested coil was comparable to that from burning 75–137 cigarettes.
That figure should not be interpreted as meaning that using one coil is medically equivalent to smoking 75–137 cigarettes. It is a comparison of measured particulate emissions under particular test conditions, not a comparison of disease risk or overall toxicity.
Different products can also produce substantially different emission levels.
Can Families Reduce Smoke Exposure?
Families can reduce indoor smoke exposure by avoiding unnecessary burning of coils in tightly closed rooms and maintaining appropriate ventilation.
Non-burning approaches, such as mosquito nets and properly fitted window or door screens, can provide physical protection from mosquito bites without adding combustion smoke to indoor air. WHO material also recognises mosquito nets as an important mosquito-control measure.
The choice of mosquito-control method should also take local mosquito-borne disease risks into account. Avoiding mosquito bites remains important, so replacing a coil with another method should still provide effective protection.
What Should People Remember?
Mosquito coils can be useful for mosquito control, but the smoke they generate is not simply harmless vapour. Research has shown that burning coils can release fine particles and other pollutants, with indoor concentrations affected by factors such as ventilation and room size.
The practical takeaway is straightforward: avoid unnecessary exposure to mosquito-coil smoke, particularly in poorly ventilated spaces, and consider non-burning mosquito-control methods where they are suitable.
Anyone experiencing persistent breathing difficulty or other concerning symptoms should speak with a qualified healthcare professional rather than assuming that mosquito-coil smoke is the only possible cause.