Measurements of airborne asbestos fibre concentrations in indoor atmospheres are made for several reasons related to short-term or long-term exposure of building occupants to asbestos. One application of such measurements is to ensure that airborne asbestos fibres dispersed in areas of a building that are undergoing asbestos abatement do not result in unacceptable exposures of occupants in other areas of the building. After asbestos abatement is completed, measurements are made prior to removal of containment barriers and before safety precautions are discontinued to determine whether any residual asbestos that may remain in the abated area could give rise to unacceptable airborne asbestos exposures when the areas are re-occupied.
The characterization and assessment of ambient air at a fixed position, whether in a building or outside, is normally based on a series of measurements made over a long period of time, generally months or years.
However, the release of asbestos fibres into ambient air is not constant, and human, or in some cases animal, activity will result in short-term release episodes. Maintenance activity, in particular, will disturb asbestos containing materials and settled dust in buildings. Control and monitoring of these activities will determine the long-term exposure levels. Workplace atmospheres are also assessed by a series of repeated measurements, the number of measurements depending on the difference between the measured value and the control limit.
In contrast to the strategy used for assessment of long-term asbestos fibre concentrations and personal exposures, the assessment of asbestos fibre concentrations in connection with asbestos abatement measures is nearly always based on a set of measurements made at one time.
This special situation needs to be taken into account, both when planning the measurements, and during collection of the air samples. It is not possible to predict long-term changes of airborne asbestos fibre concentrations resulting from any deterioration of asbestos-containing material or the type of usage of the rooms.
However, if appropriate sampling strategy and sampling technique is used, and by taking extreme, but realistic, conditions into consideration, it is possible to simulate and estimate the short-term maximum asbestos fibre concentrations that can occur.
BS EN ISO 16000-7 specifies procedures to be used in planning of air measurements to determine the concentrations of asbestos in indoor atmospheres. Careful planning of the measurement strategy is important, because the results can become the basis of recommendations for major building renovations, or for the return of a building to normal occupancy status after removal of asbestos-containing materials.
Part 7 of ISO 16000 uses the following definition for indoor environments as specified in BS EN ISO 16000-1:
- Dwellings having living rooms, bedrooms, do-it-yourself (DIY) rooms, recreation rooms, cellars, kitchens, and bathrooms
- Workrooms or workplaces in buildings that are not subject to health and safety inspections in regard to air pollutants (for example, offices and sales premises)
- Public and commercial buildings (for example, hospitals, schools, kindergartens, sports halls, libraries, restaurants and bars, theatres, and other function rooms)
- Cabins of vehicles and public transport.
Contents of BS EN ISO 16000-7 include:
Foreword
Introduction
Scope
Normative references
Sources and occurrence
Terms and definitions
Symbols and abbreviations
Measurement strategy
Quality assurance
Simulation methods
Choice of analytical method
Example of sample data form
Example of the summary report form
Bibliography