Coping with dead rodent odours
Bag hidden under table. Photo: Earth Care Products
Pest Control Professionals (PCPs) are often confronted with horrible odours from dead rodents. The death could have been natural, from the use of a rodenticide, or from a trap that struck the rodent, did not capture it, but was fatal. If the technician is lucky, they can find and remove the dead carcass. If the carcass is found and removed then the area should be treated to avoid lingering foul odours from the body fluids of the dead carcass.
Dead rodents can end up in the attic, wall void, insulation, crawl space or some inaccessible place. Demolition is an option to find and remove the dead carcass. However, this can be very costly and may not be successful in finding the carcass. In addition, the customer may not want demolition to occur due to expense and mess. If the dead carcass is in or behind a masonry wall demolition is not an option.
Outcomes from a PCP search:
Finds and removes carcass. In this case, the technician should remove or treat the affected area to rid it of the odour from the body fluids that have soaked into the surface. If the carcass is on insulation, the insulation should be removed. If it is on a structural member, the structural member should be treated to remove the odour. Otherwise a money losing call back could occur.
Searches for the carcass and cannot find it. The technician may suspect the carcass is in an attic in the insulation somewhere, or in a crawl space, or a wall void, or in some inaccessible place. After spending considerable time looking for the carcass, they are not able to find it.
Knows location of carcass but would require demolition to remove. It could be in a wall void or in an inaccessible crawl space. If it is in or behind a masonry wall then demolition would not be viable.
Dealing with the odour:
Do nothing: After hunting and not finding and removing the carcass the technician can tell the customer the odour will most likely disappear in a couple weeks and to just spray some room fragrance to cover up the odour.
Masking agents: These work well in that they cover up or mask an unpleasant smell with a more desirable fragrance. They also work right away. Sometimes a fragrance may be offensive to the customer. In either case you end up with a blend of a pleasant fragrance and dead rodent odour. Also, some customers are allergic to certain fragrances. When the fragrance wears off then the customer is left with the foul odour once again which can result in a money losing call back. The foul odour will persist until the carcass has totally dehydrated which could take two weeks or longer. Many such products are readily available and too numerous to mention.
Ozone generators: They cannot run in a room where humans or animals are present because ozone attacks the mucus membranes in the lungs and destroys fabrics. The machine must run for at least one hour, then the room must be aired out and the machine must be retrieved. If the carcass is not found and removed the odour will return when the machine is no longer running. This method is typically more costly since the technician would need to be on site two times, once to install and close up the structure, and a second time to make sure the machine is off, open up the structure to air it out and remove the machine. This would be the least desirable solution due to the health hazard, the cost of the machine, and the time on site required and the likelihood of the odour reappearing creating a call back. In addition, there is a potential liability issue. Ozone generators are often sold online falsely as air purifiers and should be avoided.
Enzyme sprays: They are usually very effective in eliminating airborne odours quickly. Enzyme sprays must come into contact with the odour producer; therefore the carcass must be found. If the dead carcass is found in an attic on insulation the technician should remove the carcass and the insulation the animal was laying on to eliminate the odour. If the carcass is on a structural member, then it should be treated with the enzyme. If not, a return visit may be requested due to the residual odour. In addition, if demolition is required to remove the carcass such as in a wall void, then the cost and time on site increase significantly, not to mention possible issues with the quality of the repair work. In addition, there is no guarantee of finding the dead carcass. Two good products available in the USA are Bac-A-Zap and Epoleon.
Anions: These are negatively charged particles that attract ions (positively charged particles), just like a magnet. Most odour molecules such as dead rodent odours, urine, musty mildew odours, etc. are ions. The anions attract the ions, which cling to the surface of the anions. Once the ion clings to the surface of the anion, typically an ion exchange takes place giving up one atom of oxygen or nitrogen and in the process totally changing the makeup of the ion, which no longer has any odour. Anions constantly adsorb the odour from a dead carcass even if the carcass is not found and removed. Assuming there is a dead rodent in an attic or wall void, to get rid of the odour simply hang a bag in every room where you smell the odour.
If the carcass is in an attic or crawl space hang an additional bag in that area as well, but always hang at least one bag in the room where people are. It is best to hang one bag per 10 square metres (100 square feet). The odour should be gone in 24 hours.
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Activated carbon (AC) can be used as an anion to adsorb odours but there are several drawbacks besides the messy black dust. AC pores clog reducing its effective life to remove odours, especially when it is expected to last until the dead carcass dehydrates. AC absorbs oxygen as well so care should be taken when used in confined spaces where people are without sufficient ventilation to replenish the oxygen. AC is highly flammable and the dust is explosive when exposed to heat or flame. The presence of water assists ignition, as do contaminants such as oil.
An excellent anion solution is the Earth Care Odour Remover Bag. EarthCare Bags use a blend of natural minerals that are put through a proprietary process that enables it to be very effective in getting rid of dead rodent odours. The EarthCare bag requires no registration, is safe to use around children and pets, is clean to use and lasts approximately three months in use.
Further Reading:
- Hazardous Ozone-Generating Air Purifiers, California Air Resources Board
- https://ww2.arb.ca.gov/our-work/programs/air-cleaners-ozone-products/hazardous-ozone-generating-air-purifiers
- Activated charcoal hazard: https://cameochemicals.noaa.gov/chemical/10765#
- OSHA Hazard Information Bulletins, Fire Hazard from Carbon Adsorption Deodorizing Systems, August 17, 1992
Author: Bill Vaughan Earth Care products, bvaughan@cleartheair.com
Published in International Pest Control – July/August 2022 issue.
Category: Public health
