Cold Weather Disinfecting
Every year there comes a time when the mercury drops and temperatures below freezing become a constant battle. Freezing temperatures make every day processes a challenge and biosecurity and sanitation are no exception to this. Consistent temperatures below freezing will have a significant impact on the efficacy of disinfectants and their ability to successfully kill microorganisms.
When disinfecting in cold temperatures, it is imperative to ensure adequate contact time for the disinfectant to kill the targeted organism(s). This can be achieved by adding antifreeze compounds to the disinfectant solutions. However, disinfecting in cold temperatures is not as simple as just pouring antifreeze into the disinfectant solution. There are many factors that need to be taken into account when disinfecting in cold weather. These factors include the antifreeze compound, the choice of disinfectant, the ambient temperature, and the targeted organisms.
There are a variety of antifreeze agents available that can be added to disinfectants to prevent freezing. Available antifreeze compounds are propylene glycol (PG), ethylene glycol (EG), methanol typically in the form of windshield washer fluid (WWF), and calcium chloride. The two most commonly used are PG and WWF. EG is not recommend for use due to its toxicity and calcium chloride is not recommended due to it being highly corrosive to metallic surfaces (Guan et al., 2015).
Both PG and methanol (WWF) are organic in nature and have the potential to react with certain disinfectant classes. When selecting an antifreeze, it needs to be compatible and miscible with the disinfectant. If there is a chemical reaction between the two products, it is likely that the efficacy of the disinfectant will be impacted which can yield unsatisfactory results. If the two products are not miscible and do not stay mixed, it is also likely to yield unsatisfactory results.
The efficacy of most disinfectant classes has been evaluated when mixed with antifreeze agents. The evaluated classes include and are not limited to phenols, quaternary ammonia compounds (QAC), QAC and glutaraldehyde blends, peroxygens, and liquid halogens. It has been shown that mixing phenols, QAC and QAC blends with PG and WWF did not result in a decrease in efficacy of the disinfectants (Davison et al., 1999). There has been concern raised around mixing antifreeze compounds with oxidizers such as peroxygens and halogens due to the potential interaction between the antifreeze and disinfectant (Blinov et al., 2014). If oxidizers are going to be used, it is recommended that the solution is used shortly after mixing or to increase the concentration of the disinfectant if the product label allows (Guan et al., 2015).
The majority of studies looking at the efficacy of disinfectants mixed with antifreeze compounds evaluated the efficacy on enveloped viruses. Enveloped viruses tend to be sensitive to a variety of biocides; therefore, the results should not be extended to other organisms or classes of organisms but examined individually (Davison et al., 1999). If there is a specific organism or organisms of concern, the manufacturer of the disinfectant should be directly consulted.
When preparing the antifreeze and disinfectant solution, the ambient outside temperature on any given day will need to be taken into account, as it will dictate the amount of antifreeze that needs to be added to prevent freezing. The colder the temperature, the more antifreeze that needs to be added. For example, a 5% PG solution has a freezing point of 29 degrees F, whereas a 50% PG solution will not freeze until temperatures drop below -30 degrees F. The rate of inclusion will be highly variable depending on temperature fluctuations and will have to be adjusted accordingly to match the temperature.
The temperature is often overlooked when equipment is washed indoors then moved outdoors after being cleaned and disinfected. Depending on the temperature, freezing of the disinfectant that has been applied can occur in a matter of minutes. Having a successful disinfection program during periods of temperatures below freezing can be done with the proper disinfectant and antifreeze mixtures.
If you have questions related to cold weather disinfecting, please reach out to your MWI Animal Health Territory Manager. We are here to help!
Blinov, V., K. Volcheck, C.E Brown, and E. Rohonczy. Cold Weather Decontamination/Disinfection Methods and Technologies, Proceedings of the Thirty-seventy AMOP Technical Seminar on Environmental Contamination and Response. Environment Canada, Ottawa, ON, pp. 198–215, 2014.
S. Davison, C.E. Benson, A.F. Zeigler, R.J. Eckroade. Evaluation of disinfectants with the addition of antifreezing compounds against nonpathogenic H7N2 avian influenza virus Avian Dis., 43 (1999), pp. 533–537
Guan, J., Chan, M., Brooks, B. W., and Rohonczy, E. (2015). Enhanced inactivation of avian influenza virus at− 20° C by disinfectants supplemented with calcium chloride or other antifreeze agents. Can. J. Vet. Res. 79(4): 347–350.