Exposure to air pollutants in hospitals: indoor–outdoor correlations

Abstract

This study presents an assessment of exposure to air pollutants in a hospital environment using several air quality indicators commonly associated with indoor and outdoor emission sources including carbon monoxide (CO), carbon dioxide (CO2), fine particulate matter (PM2.5), and total volatile organic compounds (TVOC). The distribution and variation of indoor concentrations of CO, CO2, PM2.5 and TVOC were examined in ten working areas of three hospitals randomly selected in an urban and rural setting. Indoor concentrations were then statistically correlated with outdoor sources. The results showed higher levels of CO2 (690 ± 65 ppm) and TVOC (0.30 ± 0.10 ppm) indoors (p < 0.05) compared to outdoors (471 ± 85 ppm and 0.10 ± 0.07 ppm, respectively). A high correlation (r = 0.69) was recorded between indoor and outdoor PM2.5 levels suggesting that indoor environments are directly affected by outdoor levels. At most sampling sites, outdoor PM2.5 and CO concentrations (p < 0.05) were higher than indoor levels. While the PM2.5 indoor/outdoor (I/O) ratio was less than 1 indicating a cleaner indoor environment and minimal indoor PM2.5 sources, indoor levels exceeded outdoor concentrations during a dust storm and reached a 2.6 fold higher than the WHO standard. Higher PM2.5 and CO levels were recorded in urban hospitals (PM2.5 = 81 ± 12 µg/m 3 and CO = 4.62 ± 0.71 ppm) compared to rural (PM2.5 = 27 ± 6.5 µg/m 3 and CO = 1.22 ± 0.43 ppm) suggesting the contribution of construction activities and vehicular emissions to urban levels of PM2.5 and CO in hospitals. Although affected by outdoor levels, most indoor PM2.5 and CO concentrations in both urban and rural setting remained below standards.