Indoor air quality varies with ventilation types and working areas in hospitals

• Ward and pharmacy departments have higher levels of CO2 and TVOC in hospitals.
• Central air condition can effectively remove aerosol pollutants than that non-central air condition in hospitals.
• Air conditioning types and human activities in different work areas affect air quality in hospitals.

This study aimed to investigate the distributions of indoor air pollutants in different areas of hospitals, and examine how they might be associated with various types of air conditioning systems. We measured CO, CO2, O3, TVOC, HCHO, PM2.5, PM10, airborne bacteria and fungus at 96 sites in 7 different work areas under 4 major types of air conditioning systems from 37 hospitals, randomly selected throughout Taiwan. Statistical analysis showed that there were higher levels of CO2 and TVOC in wards (p < 0.05); pharmacy departments also had higher levels of TVOC, compared to those of other areas. The average concentrations of CO, O3, HCHO, PM2.5, PM10, bacteria and fungi did not differ statistically among various work areas. The CO level was particularly higher at the hospitals with mechanical air-conditioning systems, regardless of whether the hospitals used an air handling unit (AHU) system, fan coil unit (FCU) system or mixed type (p < 0.05). This could be higher outdoor CO levels in hospitals with central air conditioning, and outdoor CO might have been drawn into indoors through ventilation system. Yet, the PM2.5, PM10 and fungal concentrations were higher at the hospitals with non-central air conditioning systems (p < 0.05). Environments equipped with central air conditioning systems appear apt to lower indoor aerosol but show no particular benefit for controlling indoor CO concentrations in hospitals. Future investigation should be designed to explore how different work areas and ventilation types could better manage indoor air quality, and therefore, benefit occupant health.