However, there is a trend to have fibre number exposure limit standards for MMMF. Existing and proposed standards in different countries range from 0.2 f/cc to 2 f/cc. A summary of international standards is presented in Annex III of Appendix I in Section 3.
6.5 - EFFECTIVE FIBRE MONITORING PROGRAMS
The three main requirements to have an effective fibre monitoring program are:
€ Commitment of management;
€ Monitoring strategy;
€ Sound measurement methods.
6.6 - COMMITMENT OF MANAGEMENT
As part of the management process, managers of every company should be concerned with the proper monitoring of employee exposure to airborne fibre. The measurement of airborne fibre in the workplace is crucial:
€ To preserve the health and safety of workers;
€ To comply with regulations;
€ To improve the working conditions of employees;
€ To promote good relationship and better productivity of their employees;
€ To ensure the survival of their company and industry.
The development and adoption of an effective monitoring plan is essential. Responsibilities should be identified to gain the effective implementation of monitoring programs for asbestos and man-made mineral fibres in the concerned industries.
An analytical framework has been developed by the Canadian Environmental Assessment Research Council (1987) for evaluating the rationale, requirements and responsibilities for pre- and post-decision monitoring programs. The following adapted framework assumes that effective monitoring consists of three elements:
€ Monitoring plan;
€ Management process;
€ Measurement objective.
This monitoring triad is in a continual process of readjustment to maintain maximum fit or congruence in a complex and uncertain situation. Experience has shown that no monitoring program is embedded in a static situation. All have elements of the unexpected; hence, the need for flexibility. Depending upon their level of congruence, these three factors can reinforce one another, or work against each other to inhibit effectiveness.
There is no such thing as one "best" strategy for all situations. However, some strategies are clearly better than others for particular situations. Guidelines are provided for comparing alternative strategies. The following are broad considerations:
- Availability and cost of sampling equipment (pumps, filter, direct reading meters, etc.);
- Availability and cost of sample analytical facilities;
- Availability and cost of personnel to take samples;
- Location of employees and work operations;
- Occupational exposure variation (intraday and interday);
- Precision and accuracy of sampling and analytical methods;
- Number of samples needed to obtain the required accuracy of the exposure measurement.
This generalized flowchart of the measurement strategy is suggested to determine the effectiveness of dust control and to assess exposure of workers.
Dusty operations
- Personal and area sampling for ambient monitoring
- Test each operation separately
- Sample at 1L/MIN for 30 minutes
- Assessment of the effectiveness of dust control
Clean operations
- Personal sampling for exposure assessment
- Select maximim risk exmployee(s)
- Sample at 1L/MIN for 6 to 8 hours
- Assessment of worker exposure