The main pollutant of concern to health during a smoke haze is the fine particulate matter or PM10 (particulate of size 10 micron and below). The health effect depends on the severity of the smoke haze as described by the PSI (Pollutant Standards Index) reading. At a PSI of 101 and above, the air quality is deemed unhealthy.

During a smoke haze, the fine particulates enter an air-conditioned building through the fresh air intake and by infiltration through openings and gaps. The particulate levels indoor can thus build up to unacceptable levels. This could have undesirable health effect on the occupants of the building and adversely affect the efficiency of the air-conditioning system.