We’re in hurricane season. Hurricane Gonzalo has filled headlines over the past week. But rather than focus on the destruction, at ThermaPure, we rebuild from the remnants. The path to mending from hurricane disaster begins with proper information.
The Real Damage Caused by Hurricanes
Extensive flooding has created significant environmental health concerns. The potential contaminants in floodwaters include a variety of biological pathogens. These pathogens present the opportunity for a number of water and excreta-related health problems and diseases. Many of these pathogens can remain viable in a structure for up to a year. Some can remain longer in a moist environment. As structures dry, many can be aerosolized and move within the building. Rodents and insects also act as vectors transporting these pathogens throughout a structure. Disinfection of this group of pathogens in flooded structures is a complex and demanding problem.
Floodwaters present non-biological contamination problems as well. Gasoline, pesticides and other chemicals may be carried by water into structures. The volatile organic compounds (VOCs) associated with many of these chemicals present a potential hazard to occupants as they slowly off-gas over the next several months.
Understanding E. Coli Testing
Typical assessment of pathogens found in floodwater focuses on the measurement of Escherichia coli. The presence of E. coli is used as a yardstick for the assumption of biological contaminants in structures impacted by floods or other sewage contaminated water. Although this assessment is generally adequate to determine the presence of sewage related biological pathogens, it may not be adequate to determine the appropriate remedial response for the structure. Some floodwater pathogens may be more difficult to kill or reduce to safe levels than E. coli.
One of the difficulties with using E. coli as an indicator pathogen for environmental fecal contamination is that its survival rate must be equal to or greater than other bacteria or pathogens found in contaminated environments. Recent studies of E. coli contaminations indicate that there is a possibility of human infection up to 10 months after the original contamination.[1] Other species are known to have even greater durability. Salmonella, for example, has a longer life outside of the host and therefore has the potential of infecting a larger number of species, including flies, cockroaches and other vectors. This may be true of other microbes as well. It is important to note that floodwater contaminated structures can remain a health concern for a long period of time. This is particularly true if the building remains moist or wet. In fact, the conditions will worsen over time.
Other Pathogens Distributed by Hurricanes
The bulk of data used in this paper regarding pathogens in floodwater is found in studies provided to assist in the management or design of water supply and sanitation systems.[2] Because of the size and magnitude of some of the hurricane floodplains the contaminated water and attendant pathogens are comparable to sewage contamination. Efficacy studies regarding the thermal death rate of floodwater pathogens are derived from these sources.
Pathogens found in buildings affected by sewage-impacted floodwaters include bacteria, viruses, protozoa, and helminthes. According to the World Health Organization (WHO) these pathogens impact human health. Although it is not the purpose of this paper to understand specific health concerns associated with these pathogens, it is the intent to understand the resolution – structural pasteurization of floodwater contaminated buildings. Included in these categories are a few of the assumed water and excreta-related pathogens.
- Bacteria:
- Escherichia coli
- Salmonella enterica
- Viruses
- Rotovirus
- Protozoa
- Giardia lamblia
- Entamoeba hystolitica
- Helminths
- Nematodes – roundworms, hookworms, Ascaris lumbricoides
- Cestodes – tapeworms
The potential for infection of occupants in a structure comes from various vectors. The vectors found to transport or transmit these pathogens in buildings include[3]:
- Feco-oral
- Water-washed
- Water-based
- Excreta-based insect and rodent vectors
- Aerosol
The importance of this is to demonstrate the dynamic nature of a floodwater-contaminated building. Occupants can be affected by a wide variety of routes and vectors making the resolution more complex. ThermaPureHeat® is the only process that effectively treats all of the pathogens present as well as impacting the vectors and routes.
Thermal Inactivity of Specific Pathogens
Temperature is a more thorough intervention process in the inactivation of enteric pathogens. According to the WHO, “…heating to pasteurization temperatures (generally 60C) for periods of minutes to tens of minutes will destroy most waterborne pathogens of concern” (Sobsey, 2002)[4]. This general statement may be adequate to recommend utilization of heat for the disinfection of floodwater-impacted structures. However, for the purpose of this paper, more specific targets have been identified to further define the efficacy of the process. The following table shows specific pathogens that can be rendered inactive by temperatures within the range of ThermaPureHeat®:
| Pathogen
Genus, Species |
Family |
Thermal
Death Rate |
Time
Required |
Source |
| Escherichia coli | Bacteria | 60C/140F | 45 minutes | Padhye & Doyle[5] |
| Salmonella | Bacteria | 60C/140F | I hour | Feachem[6] |
| Shigella | Bacteria | 55C/131F | 1 hour | Feachem[7] |
| Giardia lamblia | Protozoa | 60C/140F | 2-3 minutes | Univ of Utah[8] |
| Entamoeba hisolytica | Protozoa | 60C/140F | 1 minute | Feachem[9] |
| Rotovirus | Virus | 63C/145F | 30 minutes | G.N. Woode[10] |
| Poliovirus 1 | Virus | 60C/140F | 5 minutes | Wiley (1969)[11] |
| Enteroviruses | Virus | 60C/140F | 2 hours | Feachem[12] |
| Ascaris lumbricoides | Helminths | 55C/131F | 1 hour | Feachem[13] |
Application of ThermaPureHeat® Technology
The efficacy of ThermaPureHeat® in its simplest form is a result of the combination of temperature and duration. The complexity of any sanitization is achieving efficacy in all areas of the structure. What differentiates ThermaPureHeat® is the ability to sanitize the entire structure, including inaccessible areas. Buildings are complex and the requirement for uniform temperature throughout a structure is necessary to achieve efficacy. Heat technicians are thoroughly trained in construction materials, thermal dynamics and the intended targets. Buildings have materials that conduct heat, that create radiant losses, and that are heat sinks. The heat technician must understand each of these conditions. Temperatures are monitored real-time in difficult to heat locations. In a wooden structure these places might be under sill plates and between header boards. Crawlspaces and sub-areas provide additional difficulties. All structures can be treated by ThermaPureHeat®
The process of pasteurization of a structure appears to uniformly impact these pathogens related to floodwaters. Other methods of pasteurization are not as uniform in result. For example, Giardia cysts are resistant to chlorination and a wide range of pH.[14] Other methods may not be ovacidal such as in the case of helminths. Ascaris eggs are hardier than the larvae. Other processes are not as safe and are not as effective. Heat, as a pasteurization, is uniform and non-discriminatory in application. Pasteurization of a building is an effective process to reduce pathogens to safe levels.
Conclusion
All buildings affected by floodwaters should be sanitized. The most thorough method of sanitizing is ThermaPureHeat®. ThermaPure has extensive experience with hurricane and flooding disasters, such as those caused by Hurricane Katrina.
ThermaPureHeat® is a patented, non-chemical, engineered process that “pasteurizes” structures. This process is the most effective because it is the only process that kills or inactivates the majority of pathogens present. Additionally, it is the only treatment that inactivates these pathogens in inaccessible areas. By more thoroughly drying the structure it prevents these pathogens from vectoring from other sources and becoming viable. Vector sources include rodents, cockroaches, and other insects. Added value for the process is the reduction of VOCs that may have resulted from chemical contamination associated with the floodwaters. Much like the pasteurization of food products, ThermaPureHeat® reduces the biological contaminants in a structure to levels safe for occupants.
1 Varma, J.K., et al, (2003). “An outbreak of Escherichia coli infection following exposure to a contaminated building”. Journal of American Medical Association, 290(20), 2709-2712.
2 Feachem, R. et al,(1983). Sanitation and Disease Health Aspects of Excreta and Wastewater Management. Wiley, Dorchester, England.
3 Mara, D.D., Feachem, R.G.A., (1999) “Waterborne and Excreta-Related Disease: Unitary Environmental Classification”, Journal of Environmental Engineering-ASCE, 125 (4), 334-339.
4 Sobsey, M., (2002) “Managing water in the home, accelerated health basis of improved water supply”, World Health Organization.
5 Padhye, N.V. and doyle, M.P. 1992. “Escherichia Coli 0157:H7: Epidemiology, pathogenesis, and methods for detection in foods”. J. Food Protect. 55(7):555-565.
6 Feachem, R. et al,(1983) Sanitation and Disease Health Aspects of Excreta and Wastewater Management, Wiley, Dorchester, England, p278.
7 Feachem, R. et al,(1983) Sanitation and Disease Health Aspects of Excreta and Wastewater Management, Wiley, Dorchester, England, p294.
8 Wilderness Medicine, (2005) University of Utah, School of Medicine.
9 Feachem, R. et al,(1983) Sanitation and Disease Health Aspects of Excreta and Wastewater Management, Wiley, Dorchester, England, p342.
10 Feachem, R. et al,(1983) Sanitation and Disease Health Aspects of Excreta and Wastewater Management, Wiley, Dorchester, England, p188.
11 Feachem, et al, (1983).
12 Feachem, et al, (1983)
13 Feachem, et al, (1983).
14 Feachem, et al, (1982) p354.
