ASBESTOS RISK ASSESSMENT SURVEYS AND MONITORING SERVICES
Introduction
Scientific evaluation of all the available human data provides no evidence for a “safe” level of asbestos exposure, thus any quantity should be considered potentially dangerous. However, a health risk exists solely when asbestos fibres are released into the air and when that contaminated air is inhaled into the lungs. Even then it appears that most people exposed to relatively small amounts of asbestos do not develop problems. The fact remains, however, that the chances of developing serious respiratory illnesses, including lung cancer, are greater in those exposed to airborne asbestos fibres.
Conversely, this correctly confers that many asbestos bearing materials or products are of no health risk whatsoever when used in the normal course of events. However, any level of asbestos containing materials inside a building constitutes a hazard. It should be noted that hazard is a potential for harm, whereas risk is the probability that this potential may become actual. With this distinction, it is self-evident that a simple identification and analysis of asbestos containing materials (ACMs) is insufficient to guage the degree of risk. Since it is the airborne fraction of asbestos that is dangerous, a major factor in assessing risk conditions is to have a knowledge and understanding of the design of the building in general and its air handling system in particular. Thus, all our building surveys include a review of the ventilation system layout and operation.
Asbestos Survey
Step 1
Review all existing building records and drawings to ascertain if asbestos was specified in the building’s original construction or subsequent renovation.
Step 2
Examination of the design and operating practices of the air handling system serving the building, checking the design of the air handlers and their supply and return air systems.
Step 3
Systematic investigation of the building preferably starting at roof top level (tiles, shingles, cooling towers, surface finish of walls, etc). Progressively moving down through the ceiling voids, plant rooms, general offices, hallways, sub-floor voids, basements, garages, equipment rooms, etc.
Photographs are taken of key inspected areas and of all substances sampled. Samples are taken of all insulation materials, suspect wall materials, tiles, surface finishes, gaskets, etc.
Care is taken to differentiate between layers of materials. Surface coats, undercoats, or primers, core materials, etc. are all separately sampled. Large areas need several representative samples and all physically different materials (colour, texture, size, etc of tiles) are sampled as discrete materials.
Step 4
Building engineers are consulted to add their input. Voids, rooms, closets, garages, etc, are reviewed with the engineer and his knowledge used to locate or identify any other possible locations. Maintenance and supply stores are checked to identify ACM materials in spare tiles, adhesives, gaskets, jointing compounds, spackling, etc.
Analysis
All the bulk samples are returned to the laboratory for analysis under EPA bulk asbestos proficiency guidelines by trained analysts using polarised light microscopy and dispersion staining analytical techniques. Wherever possible. The analysis identifies other materials present.
Qualitative Risk Assessment
The qualitative evaluation provides information for estimating the fibre release potential of the asbestos and the potential exposure of building occupants to asbestos containing materials. In order to set priorities, algorithms have been developed with combine relevant factors to generate a numerical index for the potential asbestos hazard within a building or complex of buildings. Several types of risk assessment algorithms have been utilised to date. The Ferris Index and modified Ferris Index have been used respectively by the Massachusetts Asbestos Commission and the Colorado Department of Education. The EPA has used the Sawyer Index entitled “EPA’s Asbestos Hazard Evaluation Algorithm”, and the United States Navy developed a risk evaluation logarithm entitled “US Navy Asbestos Hazard Index.”
All of the above referenced algorithms compile relevant factors relating to the amount of asbestos present, such as the condition of the asbestos at the time of the inspection, a potential for physical change, and the proximity to air currents and air plenums, and the degree of potential for occupant exposure to asbestos fibres. Subjective factors such as friability, accessibility, and percentage of asbestos in a bulk sample of suspect material are combined with the relevant variables and assigned a numerical score. The factors compiled into overall indices which provide the risk assessment analyst with relative rather than absolute rankings of hazard potential.
Note: We are aware that a correlation study funded by the EPA compared airborne asbestos levels with their algorithm score for 48 sampling sites in 25 schools. This study concluded that the existing algorithm was not a valid indicator of exposure to airborne asbestos. In addition, wide variances existed between different inspectors both trained and untrained. As a result, the EPA withdrew its Asbestos Hazard Evaluation Algorithm as an assessment tool in 1983.
However, most assessment/management experts agree that despite this lack of official government endorsement, these algorithms are good for general purposes and they are currently the most practical options available in evaluating asbestos hazards.
Recognising that these studies are very subjective, care needs to be taken in ensuring that the inspectors are well trained and have extensive experience with these procedures. In each survey we undertake, we complete, as a policy, both the Ferris and Sawyer indices and compare these results with a data base of several hundred prior surveys conducted by Healthy Buildings International Inc. since 1981.
Conclusions and recommendations are then based on the data generated. However, any conclusion based on these studies should be recognised as potential risk evaluations based on qualitative data only. In all cases, when asbestos is identified, those areas adjacent to the ACM materials should then be checked for airborne asbestos.
Report and Recommendations
The findings of our asbestos survey and risk assessment analysis are compiled into a bound report for each building. These reports are fully comprehensive identifying the location, nature and extent of asbestos containing materials. Whenever possible, they are fully illustrated with relevant photographs.
Specific recommendations are made for monitoring or abatement, whether enclosure, encapsulation or removal. Priorities are set and suggestions are given as to how diverse ACM materials can be tackled concurrently with other abatement projects.
These reports become the basis of the subsequent asbestos abatement bidder specifications enabling diverse removal companies to compete on an equal footing with each other since each is fully appraised of the extent of the job.
Monitoring Services
We offer experienced, third-party monitoring of any class of asbestos abatement project. If necessary, we draw up detailed removal specifications that can be integrated in the clients’ ACM abatement bid package.
Thereafter, we review the abatement contractors specifications and qualifications. Once the project starts up, we establish a program of inspections to check the integrity of the containment areas; use of correct equipment, clothing and work practices; establishment of negative air areas; conformity with disposal permits and regular and monitoring outside the containment areas.
Prior to the removal of the containment structure, we make a visual inspection of the cleared area and take final air clearance samples. Once satisfied with the quality of the abatement contract, we direct the contractors to vacate the site. Our final report will then summarise the project providing documentation and records of compliance with recent specifications.
Independence
Because Health Buildings International does not provide any asbestos abatement services and has no links with companies which do, HBI maintains complete independence and believes that in acting as third party consultants any conflicts of interest are completely avoided. Thus, where specifications or procedures are identified and recommended, the client can be confident that there are no other commercial interests which might influence the recommendations.
