CO2 Fumigation

CO2 Fumigation

August 2023 edition: 

CO₂ fumigation works by using carbon dioxide as a pesticide to control and eliminate pests by displacing or reducing the oxygen needed to survive. Carbon dioxide is non-toxic, leaves behind no harmful residues, and is highly effective in pest management while allowing products to maintain their organic rating. CO₂ has application options for grain facilities, food producers, storage and warehousing, museums, mills, pharmaceutical production, breweries and distilleries, exports, and the outside grounds of municipal facilities, parks, and residential areas.

CO₂ as a molecule is heavier than oxygen. It can be stored in a cylinder as a gas or a liquid due to pressure. When stored as a liquid CO₂ expands 535 times its volume when it transitions to a gas which also decreases temperature due to thermodynamics. These characteristics can be a challenge when using CO₂ to control pests.

 In the way of rodent control at the burrow the weight of CO₂ is an advantage, as is the respiration rate of the target, however the expansion rate is a challenge. The amount of CO₂ needed to affect rodents is relatively low targeting only 30-70% concentration of the air in the treated space. CO₂ in this case would be in a cylinder under pressure as a gas rather than a liquid. From this container a simple gas regulator is utilized to slow the gas enough that it does not create a cooling effect or any type of auditory disturbance that would send the target fleeing. By closing off alternative exits connected in a network of burrows, and through slow silent introduction, rodents have been very successfully controlled using CO_2. 

When using CO₂ to control insects the approach seems worlds apart. In large spaces or structures, CO₂ can be difficult to contain as the target concentration would be 70-80% for a much longer window of time. When targeting insects, it is preferred to have CO₂ as a liquid under pressure for transportation and efficiency of application. This is why industry typically isolates products to a smaller and tighter method of containment to treat for insect targets, either in a specialized chamber that can control atmospheric pressure and use those advantages alongside CO_2, using a tarpaulin chamber, or even a well-sealed tarp fixed to a finished concrete epoxy coated floor. Vacuum is used in these scenarios to draw down the total amount of air in the vessel so that a higher concentration of CO₂ can be achieved. There has been some testing completed of regulated flushing systems that have proven to be very effective. They require more time to reach equilibrium but have far fewer dips in concentration during the time of treatment.

CO₂ treatments have often been lumped in historically with many other types of oxygen depletion methods as oxygen is a required molecule for life pest or otherwise. As the molecule now has a label as a pesticide in most of the United States, it lends itself to the market as a viable fumigation option. Availability has been its greatest challenge. In small quantities, it could get to market intermittently, especially in the Midwest, but those challenges seem to be getting resolved. As it becomes more available in larger quantities, I do believe it will be more widely used to target insects especially in organic food products, in route between facilities to prevent the possible transportation of pests or to isolate at-risk products that cannot be exposed to more commonly used fumigants and retain their organic ratings.