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the use of exposure limits implies examining only one pollutant after the other in isolation, without taking into account the combined effect of exposure to more than one pollutant and the possible interaction of the various pollutants which can be present at the same place.
The practice in Hong Kong is that Occupational Health Officers Occupational Hygienists investigate cases of possible air-pollution in the working environment. When they find that the pollution, due either to pollutant or a group of them, is likely to present hazards to health, they will advise the employers to take preventive or remedial action to bring the pollution within the current TLV. It is not practicable to specify the exposure limits beforehand.
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The United Kingdom Codes of Practice for industrial noise form 'the basis of criteria for Factory Inspectors to determine the existence of noise hazard or otherwise. At present there are no criteria for hazards relating to vibration.
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Regarding the Direct Request made by the Committee of Experts, the Hong Kong Government would like to report that the criteria or limits of occupational hazards due to air pollution have not been laid down in legislation. The standards adopted administratively are in line with the most recent knowledge on toxicity of the air pollutants. It is felt that if the standards are written into legislation, there will be less flexibility in adopting the new standards. With the present set up of the Occupational Health Division in Hong Kong, it is not possible to draw up its own standards. The approach taken is to adopt the current Control Limits and Recommended Limits listed in the Guidance Note Environmental Hygiene EH-40 published recently by the Health and Safety Executive of the United Kingdom as the criteria and standard for the workplace environment. Reference is also made to the Code of Practice published by the Health and Safety Executive in drawing up codes of practice for local industries.
chemicals not listed in the EH-40, reference is made to the Threshold Limit Values (TLV) of the American Conference of Governmental Industrial Hygienists (ACGIH), Permissible Exposure Limits of Occupational Safety and Health Administration (OSHA) and the recommendations of the National Institute of Occupational Safety and Health (NIOSH) of the USA. Through administrative procedures, the Government has set limits to air pollution in workplaces as stipulated in the various codes of practice on asbestosis, silicosis and byssinosis. To avoid adverse health effect due to air pollution, the course of action is to reduce the airborne concentrations of contaminants to the minimum. For situations where the airborne concentrations of the pollutants are below the TLV, staff Of the Occupational Health Division still advise on reasonable and practicable preventive measures to be taken to abate the pollution.
situations where the air pollution exceeds the standard,
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