Environmental officials are reviewing the daily air pollution index to reduce confusion caused by terms used to describe air quality.
Terms used - 'good, moderate, unhealthy and very unhealthy' - may be changed to more objective descriptions.
Environmental Protection Department assistant director Tse Chin-wan said the index was accurate, but had caused misunderstanding.
Three indexes for different localities and terms used to define air quality had caused confusion, he said.
Mr Tse said descriptions such as 'high', 'medium' and 'low' were options under consideration which would be more in keeping with an index of pollution rather than air quality.
However, he added: 'The fact we have mostly moderate descriptions over the year does not mean air quality is good. We have a very high background of respirable suspended particulates therefore air pollution is a major problem.' Two additional roadside stations will be set up in Causeway Bay and Central and a separate roadside index started this year.