Indoor Air Quality and Related Health Impact in an Electronic Factory, an Office and a Winery in Malaysia.

Abstract

Indoor Air Quality is the quality of air within a building that affects the health of occupants. Both indoor and outdoor air quality are issues of growing concern. In the past, there has been more emphasis on outdoor air quality. However, it is now accepted that the effect of indoor air quality may be more significant because occupants spend 90% of their time indoors daily. In factories, indoor air may be contaminated by both chemical and biological agents, which are sometimes related to the industrial processes involved. The indoor concentrations of these contaminates may also be influenced by physical factors such as humidity, temperature, light and dust. Various health problems have been associated with indoor air quality in both office and factory environments. These include allergic reactions such as hypersensitivity pneumonitis, allergic rhinitis and asthma. Health problems may also occur as a result of direct infection from a microorganism, like Legionellosis, or from release of chemical or biological toxins such as Lipoid pneumonitis, bronchitis and humidifier fever. This study aims to identify and isolate microorganisms from air samples in the two factories and an office environment in Malaysia. Air samples were drawn using an Ideal Air Sampler. Trypticase soy agar (TSA) was used for the isolation and sub-culturing of non-fastidious bacteria. TSA enhanced with hemin, NADH and CO2 was used for the isolation and sub-culturing of fastidious bacteria. Cycloheximide was added to the medium at a concentration of 12ml/L to inhibit fungal growth. Sabouraud’s dextrose agar (SDA) was used for isolation of non-xerophilic fungi while dichloran glycerol agar (DG-18) was used for isolation of xerophilic fungi. Chloramphenicol was added at a concentration of 0.05g/L to inhibit the growth of bacteria. Identification of the yeasts and bacteria was undertaken using commercial biochemical kits. CFU was calculated according to the Ideal Air Sampler (Biomerieux BBL) manufacturer’s manual provided. Light intensity was measured with a LUX/FC light meter (Tenmars, Taiwan). Temperature and relative humidity were measured with a Hygrometer (Comark, UK). An independent company was contracted for sampling of the chemical parameters. The sample size for the questionnaire survey was determined using Raosoft ® sample size calculator with 10% margin of error, 95% confidence interval and 50% error distribution rate. An interviewer-administered questionnaire was used to collate data on the health status of workers. All data collected from six sampling events at the three study sites were analysed using Excel 2003 and SPSS Version 16.0 (SPSS. Inc., Standard Version). Indoor microbial loads were generally greater indoors than outdoors at the three study sites. The electronic factory had the highest indoor microbial counts (in the order of 102 to 103 CFU/m3 of air). Most of the micro-organisms identified are not pathogenic to immune gg bbbbbbb hy,h,hybtgvft5gujm icompetent individuals but some like Micrococcus luteus, Kytococcus sedentarius, and Cryptococcus laurentii amongst others have been implicated in infections ., c x occurring in immunocompromised individuals. Micrococcus luteus and Kytococcus sedentarius were the dominant bacteria both indoors and outdoors of the three study sites. The dominant yeast species inside the electronic factory was Cryptococcus laurentii. Gram positive cocci were the most dominant group of bacteria at the three study sites, Gram positive rods were isolated in lower proportions while Gram negative bacteria were seldom isolated. Light intensity was generally higher outdoors than indoors. The outdoor light intensity had a significant effect on indoor microbial loads. There were significant negative correlations between outdoor light intensity and indoor microbial loads due to the bactericidal effect of ultraviolet light. The relative humidity observed was in the range 52% to 69% at the three study sites. All these ranges fall below the permissible limit but are high enough (above 50%) to support microbial growth. The temperature range at the office was between 22 to 240C while the temperature range at the winery and electronic factory fell between 28 to 320C and 28 to 300C, respectively Formaldehyde was not detected at the electronic factory and office but this does not rule out the possibility of its presence. It is most probably present below detection limits. However it was detected at the fermentation area in the winery at concentrations above the recommended level for industries. Carbon dioxide was detected below the recommended level at most sampling points. This study did not establish any line of causation between the isolated micro-organisms and the identified health effects at the study sites. However, there were some statistically positive correlations between some isolated micro-organisms and some identified health symptoms, albeit with low r – correlation coefficient - values. This study has provided baseline data from which further pathogenicity studies may be undertaken on the health effects of micro-organisms identified to immunocompetent individuals.