Suggested Practice for Remediation of Highly Infectious Biological Agent Contamination in Indoor Environments

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This suggested practice describes those basic procedures to be followed, and precautions to be observed, when performing remediation and restoration of non-laboratory indoor environments known or suspected to harbor contamination from potentially infectious biological agents, especially those recognized as being easily aerosolized and thus presenting an inhalation risk. This would include contamination from potential biowarfare agents, i.e. weapons of mass destruction, such as the spores of Bacillus anthracis , the causative agent of anthrax.

The source of the contamination is often identified as a dust or powder or similar substance capable of being aerosolized. In some cases, environmental sampling and analysis identifies one or more specific areas of contamination, without identification of an initial source material. In either situation, the remediation and restoration practices are the same. In all cases, the scope of effort focuses on prevention of further contaminant dissemination, the physical removal of the offending agent(s), and the subsequent reduction of exposure risks to the workers, building occupants, and the public at large, with restoration of the environment as it was prior to the biological incident. Attention to detail and the use of common sense should always prevail.

Recommendations contained in this document are based upon information contained in various relevant guidance materials from a number of organizations including OSHA, NIOSH, CDC, DOJ, EPA, ACGIH, and the IICRC. These are identified at the end of this document

Response teams must be properly trained and equipped HAZMAT teams, as defined by the HAZWOPER standard, to include participation in a medical surveillance program. Such teams shall utilize a HAZMAT equipment vehicle that carries all personal protective equipment (PPE) and control equipment that allow the teams to enter an 'immediately dangerous to life and health' environment.

It is anticipated that calls for remediation and restoration of indoor environments with suspected or confirmed contamination with biological agents will occur following the evacuation and closure of the facility, in conjunction with the shutdown of all HVAC systems.

Consistent with current CDC recommendations, each worker must minimally utilize a powered air-purifying respirator (PAPR) with full facepiece and high efficiency particulate air (HEPA) filters, disposable protective clothing with integral hood and booties, and disposable gloves. If it has been determined that an aerosol generating device was used to disseminate the airborne agent, or similar conditions exist, then a NIOSH-approved, pressure-demand SCBA, in conjunction with a Level A protective suit is recommended. Respirators should be used in accordance with a respiratory-protection program that complies with the OSHA respiratory-protection standard (29 CFR 1910.134). Wearing disposable rubber shoe coverings with ridged soles made of slip-resistant material over the booties of the disposable suit will reduce the likelihood of slipping on wet or dusty surfaces. Protective clothing should be removed and discarded before removing the respirator. Disposable gloves should be made of lightweight nitrile or vinyl. All PPE should be decontaminated immediately after leaving a potentially contaminated area.

Identification of a localized source of contamination may require full-scale containment commensurate with current mold remediation and asbestos abatement practices. Fullscale containment requires the use of a sealed critical barrier of polyethylene in conjunction with the use of a negative pressure air machine that exhausts air out of containment through a HEPA filter unit and then to the outdoor air.

Both within and without a full-scale containment area, the remediation effort focuses on the physical removal of the spores or other agent and their related dusts and other particles. A key to effective remediation involves controlling the secondary aerosolization of airborne spores and related particles that can be expected to occur during the cleaning process. Thus the use of portable, high-volume, HEPA-filtered air scrubbers, or controlled and HEPA-filtered HVAC airflow for a particular zone, or the entire facility, is required

All surfaces and materials should be thoroughly vacuumed using HEPA-filtered vacuums. Hard surfaces should be wet wiped using a suitable detergent. Visible amounts of loose suspect powders and dusts can be contained in wet cloths and secured in airtight plastic bags. Care should be taken when bagging such items to minimize creating puffs of air that might spread the contamination. The use of biocides, particularly in regard to anthrax contamination, should be precluded. Aqueous and gas-phase biocides are impractical, since an attempt to inactivate bacterial spores would require: a) an extremely efficient and currently unavailable delivery system necessary to penetrate all areas, and b) the use of high chemical concentrations and extended contact times. Potential worker exposure, as well as harm to valuable materials from direct biocide contact or from its damaging residuals, is an additional deterrent to their use.

Following thorough vacuum cleaning, carpet and upholstered furniture can be cleaned using an extraction process as described in the IICRC carpet and upholstery cleaning standards. HEPA air scrubbing should then continue for an additional minimum of 72 hours.

Clearance Testing. Designed on a case by case basis, a clearance testing protocol should be implemented to include sampling of representative areas and materials using composite wipe samples for detection of the presence of the biological agent, followed by acceptable analytical techniques, such as rapid PCR or other recommended methods. Absence of the biological agent (e.g. anthrax spores) from all samples collected, would provide presumptive evidence of remediation effectiveness, and permit re-occupation of the building.

Mechanical Hygiene. Building HVAC systems should be assumed to be contaminated, and therefore must be contained, inspected, thoroughly cleaned, and cleared through sampling and analysis, as previously described. Again, the remediation emphasis should be on physical removal of contamination rather than the use of biocidal agents.

Decontamination of PPE and equipment is essential. Therefore, an area for washing of protective clothing to remove potential biological agents and associated particles prior to removal of the gear must be available. Likewise, all cleaning equipment must be decontaminated by thorough washing, rinsing, and drying.

All disposable materials used in the remediation are to be disposed of according to applicable local, state and/or federal requirements. At the present time, a number of states consider all potentially contaminated materials from an anthrax remediation site to be potentially infectious medical wastes and are to be treated and disposed of according to current medical waste regulations. An initial, yet unofficial recommendation of the USEPA is to treat such materials only by incineration or steam autoclaving.

Biological remediation workers should be thoroughly trained and knowledgeable about the clinical symptoms of the disease agents to which they may be potentially exposed, and notify a pre-designated physician or medical center immediately if any symptoms or suspected symptoms occur. Consensus statements on biological warfare agents have been published by the American Medical Association and are excellent training resources (Inglesby 1999).

Only those workers who have previously undergone medical screening and are designated as healthy should serve as biological agent remediation workers. This includes completion of a thorough physical examination, as well as acceptance of appropriate, recommended, and available immunizations.

ACGIH. (1999). Shaughnessy, R. J. and P. R. Morey, Remediation of Microbial Contamination . In : J. Macher, ed., Bioaerosols: Assessment and Control, American Conference of Governmental Industrial Hygienists, Cincinnati, OH.

CDC. (2001a). Interim Recommendations for the Selection and Use of Protective Clothing and Respirators Against Biological Agents, Centers for Disease Control and Prevention, Atlanta, GA.

CDC. (2001b). Protecting Investigators Performing Environmental Sampling for Bacillus anthracis: Personal Protective Equipment, Centers for Disease Control and Prevention, Atlanta, GA.

IICRC. (1999). Standard and Reference Guide for Professional Water Damage Restoration (S500), 2nd edition, Institute of Inspection, Cleaning, and Restoration Certification, Vancouver, WA.

IICRC. (1997). Standard and Reference Guide for Professional On-location Cleaning of Installed Textile Floor Covering Materials (S001 Carpet Cleaning Standard), Institute of Inspection, Cleaning, and Restoration Certification, Vancouver, WA.

IICRC. (2000). Standard and Reference Guide for Professional Upholstery Cleaning (S300 Upholstery Cleaning Standard), Institute of Inspection, Cleaning, and Restoration Certification, Vancouver, WA.

Ingelesby, T.V. et al. (1999). Anthrax as a Biological Weapon - Medical and Public Health Management, JAMA, 281:1735-1745.

NIOSH/NCID. (1997). Histoplasmosis: Protecting Workers at Risk, Centers for Disease Control and Prevention, Atlanta, GA.

OSHA. (1994). Standards Interpretation and Compliance Letters - Members of a HAZMAT Team, Occupational Safety and Health Administration, Washington, DC.

USDOJ. (2001). State and Local Approaches - Mass Casualty Decontamination: Massachusetts' Rapid Response System, U.S. Department of Justice, Washington, DC.

USEPA. (2001). Mold Remediation in Schools and Commercial Buildings, United States Environmental Protection Agency.

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