Criteria for air quality in enclosed car parks

This paper addresses concerns about the environment found within enclosed car parks in Hong Kong. These concerns have been expressed in terms of the levels of carbon monoxide found in car parks following a survey. The outcome has been the development of a code of practice for car park ventilation system design and performance. It is recognized, however, that too stringent criteria may lead to over-design of ventilation systems and unwarranted use of energy. The criteria need to take into account the levels of exposure likely to be experienced by two separate groups - car park users and car park employees or maintenance contractors. In public car parks the former group embraces the entire population as drivers or passengers, whilst the latter group can be expected to include only working adults. The criteria for exposure for each group are considered with respect to various health and occupational guidelines used in developed countries. In addition, the potential for impairment of driving performance is considered. Criteria for safe exposure levels in car parks are recommended.