Investigation of BTEX and Ozone Concentrations in a Printing Facility in Bangkok, Thailand

The presence of Volatile Organic Compounds (VOCs) in ambient and indoor air is widely recognized as precursors of serious risk to human health. In addition, VOCs contribute to the production of secondary photochemical pollutants such as ozone. Many studies have shown that printing processes lead to indoor emissions of VOCs. In this study, the concentration of four VOCs namely benzene, toluene, ethylbenzene, xylene (BTEX) and ozone in a large printing facility located in Bangkok, Thailand. Air samples were collected and analyzed at the working place (sheet offset printing) during working time (8 hr) using portable ambient air analyzers and colorimetric method from June to September 2005. The concentration ranges of benzene, toluene, ethylbenzene and xylene were 63.9–126.1 ppm, 1.3–2.1 ppm, 0.8–6.5 ppm and 1.1–2.7 ppm, respectively. The four month-average concentrations of benzene, toluene, ethylbenzene and xylene species were 101.7 ± 28 ppm, 1.7 ± 0.3 ppm 3.0 ± 2.5 ppm and 1.9 ± 0.7 ppm, respectively. The concentration of benzene, which is found as the most prevailing VOC, exceeded the recommended maximum level of 5 ppm set by the American Conference of Governmental Industrial Hygienists (ACGIH). The measured concentrations of toluene, ethylbenzene and xylene showed levels below the recommended maximum level set by ACGIH. Ozone concentration remained below 0.01 ppm over four months of measurement campaign, and hence much lower than the ACGIH standard. The observed low concentration of ozone is probably due to low concentrations of the three VOCs associated to low light intensity in the printing facility.