Review of the objective pollutant levels in the iaq certification scheme

The Indoor Air Quality (IAO) Certification Scheme is one of the major components of the IAQ Management Programme proposed by the Hong Kong SAR Government. The Scheme incorporates the Guidance Notes (GN) on the Management of Indoor Air Quality in Offices and Public Places. The draft GN issued in November 1999 has been under scrutiny and Subject to trial implementation. The IAQ objectives stated in the GN define indoor concentration standards for 9 major air contaminants on a health-related basis, as well as requirements for 3 physical indoor environmental parameters. This paper critically reviews the rationales for the IAQ criteria based on the standards adopted in other countries and recommended by several international organisations. It is concluded that a number Of Level-2 criteria should be revised to a certain extent in order to maintain an appropriate level of protection for the general public. It is argued that there exists a misconception of a-hour averages for both respirable suspended particulates (RSP) and nitrogen dioxide (NO2). For carbon dioxide (CO2), the benefits with compliance to the Level-1 criteria Of the IAQ Objectives are found to be limited, yet the cost of compliance may be high. A number of recommendations are made for refining the IAQ Objectives in the GN.