It is important to emphasize that chemical fogging should be an adjunct to conventional disinfection and not a replacement for traditional decontamination. The use of disinfectants on visibly soiled areas/surfaces and the complete scrubbing and wiping down of trays, tables, chairs, lights, and instruments are of greater importance in the SARS-CoV-2 era than ever before. The addition of fogging is designed to address the aerosolized threat and to allow disinfectants to fumigate into spaces that are not otherwise reachable by wiping.
To fog a liquid is to create a mist of very small particles. The mist is released into an enclosed space. Over several minutes, the mist lands on surfaces, where it helps kill bacteria and viruses, before evaporating shortly thereafter. Foggers use large amounts of low-pressure air to aerosolize liquids before dispersing the mist through a nozzle. Traditional spraying creates particles in the 50-micron range, while fogging a liquid can result in fine particles less than 20 microns in size.
Since the 1980s, ultra-low volume foggers have become quite important in the greenhouse industry as the fogging of pesticides has become the mainstay of insect control. Fogging, rather than directional spraying, has superior surface area coverage: the fog lingers, allowing it to fully envelop a space, including hard-to-reach areas. The process is relatively automated and very little labor is involved except for filling the solution tanks and moving the fogging machines. In greenhouses, many of the pesticide targets are smaller than 50 microns, so ULV fogging’s ability to create small particles is crucial.
With the ongoing pandemic, fogging is increasingly important in augmenting conventional disinfection to allow for inexpensive, quick, and effective disinfection of large areas. In all instances, fogging is not a replacement for traditional spray-down and wipe-cleaning protocols, but it is a potent complementary technology.
Many sectors have started using chemical fogging to help combat the coronavirus:
Airline industry: Since February, Delta Airlines has been fogging the insides of planes arriving from Asia. Other airlines soon followed suit (American, United, Frontier).
Hotels have also begun to fog; Marriot plans to roll out fogging devices to more than 7,000 of its hotels over the next several months.
Hospitals: Early in February, Halosil International sent 150 foggers to Chinese hospitals.
In many instances, the chemical being fogged is not disclosed. Reports simply indicate the substance is not toxic to humans after application.
Cruise lines have been the first to indicate they are using hypochlorous acid as a safe disinfectant. Norwegian Cruise Line is using chemical fogging to disinfect public areas, cabins, and galleys on its cruise ships.
Fogging is also an important adjunct in disinfecting trains, buses, schools, nursing homes, offices, warehouses, and grocery stores.