Study summary
Environmental health risks and benefits of the use of mosquito coils as malaria prevention and control strategy
Hogarh JN, Agyekum TP, Bempah CK, et al.
Read the original paper- Study type
- Review
- Year
- 2018
- Published in
- Malaria Journal (2018), PMC6048806
- Evidence strength
- Well-supported evidence
Summary
The mosquito coil is the oldest and cheapest airborne repellent device, a spiral you light so that it smolders and releases a pyrethroid such as allethrin or pyrethrins into the air. This review weighed both sides of the coil: how much it actually protects against mosquitoes, and what the smoke does to the people breathing it. It is a helpful reality check for anyone reaching for coils as a low-cost area repellent, because it puts modest efficacy next to a real air-quality cost.
Key findings
On the efficacy side, the review found that mosquito mortality from burning various coils averaged only about 24 to 64 percent, which the authors judged too low to rely on for serious protection, especially against disease vectors. On the health side, burning a coil is combustion, and it releases fine particulate matter (PM2.5), carbon monoxide, and volatile organic compounds, along with other combustion byproducts documented in the coil literature such as formaldehyde. The review notes that coil smoke has been implicated in respiratory harm and lung cancer in prior research, while its own quantitative risk characterization found aggregate exposure under typical use fell below standard hazard thresholds. The honest buyer takeaway is that coils deliver only partial mosquito control while adding indoor and near-field smoke you would generally rather not breathe, so they are best used sparingly and in well-ventilated outdoor air.
Limitations
This is a review that pools coil products of widely varying quality and composition, so both the efficacy range and the emissions vary a great deal by brand, coil, and ventilation, and no single number describes them all. The health risk estimates depend on assumptions about room size, ventilation, and how long and often a coil burns, and the review itself reaches a nuanced rather than alarmist conclusion. It does not settle long-term health outcomes for regular users, and coil performance against any given local mosquito was not the focus.