Removing asbestos in workplaces - Compliance ... - WorkSafe Victoria

Appendices300mmThe breathing zone.300mmAppendix H – Exposure standard andatmospheric monitoringHow is an employee’s exposure determined?Employees’ exposure to asbestos can be determined through personal atmosphericmonitoring and comparing those atmospheric monitoring results with the asbestosexposure standard.What is personal atmospheric monitoring?Personal atmospheric monitoring involves the use of sampling and analyticaltechniques to obtain an estimate of the level of airborne asbestos inhaled byemployees. This level is then compared with the asbestos exposure standard.Under the asbestos part of the Regulations, these measurements must be made inaccordance with the Australian Safety and Compensation Council’s Guidance NoteMembrane filter method for estimating airborne asbestos dust 2nd Edition [NOHSC:3003 (2005)].What is the exposure standard?The asbestos part of the Regulations set the exposure standard for all forms ofasbestos at 0.1 fibres per millilitre of air (0.1 f/ml). This standard is expressed as atime-weighted average fibre concentration of asbestos calculated over an eight-hourworking day. An exposure standard represents an airborne concentration of aparticular substance in the breathing zone, which according to current knowledge,should neither impair employees’ health nor cause them undue discomfort.The breathing zone is defined as a hemisphere with a radius of 300mm extendingin front of a person’s face measured from the midpoint of an imaginary straight linejoining the ears.Exposure standards do not represent ‘no-effect’ levels at which every employeecan be guaranteed adequate protection nor do they constitute a ‘fine line’ betweensatisfactory and unsatisfactory working conditions.The results of the atmospheric monitoring are compared with the asbestos exposurestandard to determine if an employee’s exposure to asbestos is excessive.Results of atmospheric monitoring can only be directly compared to the exposurestandard if personal monitoring was performed in the breathing zone of the employeeover a continuous period of not less than four hours and the sample is consideredrepresentative of exposure.The results of static or fixed position monitoring should not be used as an indicatorof actual employee exposure to a substance. However, in certain circumstances,static or fixed position monitoring can help in determining the design of risk controlsor the effectiveness of existing risk controls.When is atmospheric monitoring required?Personal atmospheric monitoring must be carried out to determine employees’exposure to airborne asbestos fibres if, based on reasonable grounds, there isuncertainty as to whether the exposure standard has been exceeded.In other words, atmospheric monitoring is needed if risk to health cannot bedetermined with confidence by simply reviewing the information about asbestosand examining the nature of the work.WorkSafe Victoria Compliance code / Removing asbestos in workplaces 95