Filtration
Filtration – An Essential Element of the ThermaPureHeat® Process
The ThermaPureHeat® process involves a series of steps to assure efficacy, including, among others, setting temperature targets, probing or monitoring temperatures, protecting building materials and personal belongings, and protecting workers and occupants of the structure. The ThermaPure® training program provides much instruction on the issue of protecting workers and occupants, but one of the most important elements of this training and implementation is the use of filtration. Indeed, this is the element that differentiates ThermaPure’s process from other types of heat treatment. In a recent PCT Magazine article, “A Unique Heat Treatment”, ThermaPure executives discuss the merits of this popular process.
(click here to read PCT article)
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Convective Heating Generates Aerosol
ThermaPureHeat® is an engineered application of heat to a structure or portion of a structure. To accomplish this application, significant amounts of heated air are moved throughout a structure or the portion of the structure being treated. This convective heating process is engineered to provide uniform temperatures, set to meet the target criteria for the organism or objective of the heat treatment process. Convective heating processes generate tremendous amounts of aerosol.
It is likely this aerosol may be harmful to both the workers providing the treatment and the regular occupants of the structure. For this reason ThermaPure stresses the importance of filtration as a part of remediation process. This is true regardless of the target, it is not the target that creates the particulate, but the environment of the space. Normal household dust can include biological allergens and pathogens such as insect parts, mold and fungi, bacteria, dust mites and may include parasites and viruses. It will also include chemicals, dusts, pollens, and dirt. Applying a convective heat process in an occupied structure, regardless of the level of cleanliness, will generate large amounts of aerosol. This is a fact.
Michael Geyer, PE, CIH, has studied and reported the effects of convective heat applications in structures and determined that significant levels of aerosol are generated. Levels high enough in some areas to require engineering controls and personal protection for workers. In his article, “Active Dry Heating for Bed Bug Eradication without Air Filtration is Dangerous and Negligent”, Geyer summarizes his article:
…heating structures or areas within structures is fast becoming the most effective bed bug eradication method and as a remediation technique. Effective structural heating relies on equal and uniform distribution of the hot air and this is best accomplished with aggressive air mixing. However, aggressive air mixing generates significant aerosols. Methods exist to control the aerosols and they should be judiciously implemented to do so – HEPA-filtered fan units are the best available control technology to mitigate aerosols generated during active heat treatment. Failing to control the aerosol generated during an effort that employs aggressive air mixing may be negligent, because studies have indicated that it is very likely to be harmful or injurious to persons exposed to the post-treatment aerosol. (To read this excellent article in its entirety, click here)
Filtration Required in Water Loss Restoration
Other industries utilizing high temperature technologies, such as water loss restoration, also recognize the necessity for filtration as an integral part of the process. Kevin Fisher is the Education Program Manager for Dri-Eaz Products, who, according to their website “provides the world’s best solutions for restoration, remediation and portable environmental control”. Mr. Fisher is a recognized expert in the restoration industry as an approved IICRC instructor in Applied Structural Drying (ASD) and Water Damage Restoration (WRT) and has authored many industry publications. In one of those publications, “Using Air Filtration in Water Loss Restoration”, Mr. Fisher states:
Because today’s customers are more concerned with indoor air quality, air filtration is often used for customer – and employee – safety and peace of mind. Air filtration devices, or AFDs, are needed in water restoration work whenever the job involves:
• contaminated water
• contaminated structure
• high levels of particulates being added to the air
• strong air movement.
Typically, at least one of these conditions exists in every drying environment. Air filtration is a must whenever there are building occupants who might be at higher risk for discomfort or illness from an elevated level of particles in the air (e.g. the very young, the elderly, or those with respiratory problems or a compromised immune system). When walls or other cavities are known to contain particles, drying systems should include AFDs.
Other experts have also provided strong input to the necessity of filtration as a part of the engineering control requirements of a remediation project. Abatement Technologies, a “worldwide leader in the design and manufacture of powerful air abatement products that remove harmful particulates, bioaerosols and volatile organic compounds” has argued strongly for the use of filtration devices in every water damage remediation job. (Link to Article) They argue:
It is very important to note that the very activities undertaken to remediate the problem can increase the risks of air contamination. For example, as forced-air drying evaporates water from surfaces, carpet and other materials, contaminants such as fungal spores and ultra-fine dust and dust particles are likely to be released into the air. Once aerosolized (suspended in air), workers exposed to these pollutants can inhale them. Particles stirred up during remediation also create housekeeping and cleanup issues that can increase the cost of the cleanup.
Airborne Particulate is Unhealthy
There is a preponderance of medical evidence regarding the health effects of airborne particulate. Much of the research was done to evaluate the health effect of outdoor air. These studies apply to indoor air quality as well because the concern is about particulate size, type and abundance. Outdoor environments tend to replicate themselves indoors. Indeed, conditions indoors may be worse because of housekeeping standards or other environmental factors such as water loss occurrences, chemical use, or pesticide application. Abatement Technologies discussed particle size and suspension:
Studies have shown, however, that more than 99% of the particles suspended in air are ten microns (0.0004 inches) or less in size. That’s five to 10 times smaller than a human hair and smaller than we can see with the naked eye. Particles and allergens this tiny are typically light enough to remain aerosolized for long periods of time and can readily spread through a building or home on air currents, and they are easily re-aerosolized when they do settle onto surfaces. They also pose the greatest potential health threat.
The health effects of particulate exposure are well known. The American Lung Association has numerous data and publications on this topic.
While larger particles (those greater than 10 microns in diameter) get caught in the nose and throat, and are cleared naturally by coughing or swallowing, particles smaller than 10 microns in diameter are easily inhaled into the lungs. Of these, the smallest particles are most likely to reach the alveoli, where they can remain embedded for years, or in the case of soluble particles, be absorbed into the bloodstream. For this reason industrial hygienists often refer to them as ‘lung damaging particles’.
The American Lung Association has also compiled the numerous studies on health effects and concluded the following:
According to the findings from some of the latest studies, short-term increases in particle pollution have been linked to:
• Death from respiratory and cardiovascular causes, including strokes,
• increased numbers of heart attacks, especially among the elderly and in people with heart conditions,
• increased hospitalization for cardiovascular disease, including strokes and congestive heart failure,
• increased breathing difficulty and need for asthma inhaler,
• hospitalization for asthma among children; and
• aggravated asthma attacks in children.
The U.S. EPA has recognized indoor particulate as a potential health problem. The following statement is found on a grant application to the EPA for research on this topic:
Recent epidemiological studies have shown that exposure to suspended airborne particulates, especially to the thoracic fraction and finer particles, can lead to adverse health effects. Such conclusions have prompted the U.S. Environmental Protection Agency (EPA) to revise National Ambient Air Quality Standards (NAAQS) to include both PM10 and PM2.5 (particulate matter with aerodynamic diameters less than 10 µm and 2.5 µm, respectively) to further protect public health.
People spend more time indoors (more than 85%) than outdoors (less than 15%). Therefore, exposure to indoor particulate contaminants can constitute a higher potential health hazard than that of outdoors.
Conclusion
Indoor airborne particulate generated by convective heating processes, such as ThermaPureHeat®, require the use of engineering controls, specifically filtration, to manage the aerosol. This is an integral part of the ThermaPure process and should be a standard in all drying applications and remediation efforts where a convective process is used.
