Mosquito coils, despite of having been categorized as a source of indoor air pollutant, are still widely used for fumigating mosquitos in Taiwan. Several epidemiological studies have shown that smoke from the mosquito coils has harmful effects on health. For instance, smoke from burning mosquito coils increases the prevalence rate of asthma and persistent wheezing among children between the ages of seven and twelve (Azizi and Henry, 1991). Furthermore, burning mosquito coils is found to be a significant risk factors for epidermoid carcinoma and adenocarcinoma in lung (Chen et al., 1990). Some animal studies also demonstrate the pernicious effects of burning mosquito coils. One study (Liu and Wong, 1987b; Liu and Sun, 1988; Liu et al., 1989) finds that smoke from burning mosquito coils causes morphological, biochemical and cellular changes in the respiratory system of rats, while another study (Moorthy and Murthy, 1994) shows that it raises the frequency of chromatid exchange and chromosomal aberration in rodents. The Ames Salmonella test with TA98 identifies the mutagenic effects of particulate aerosol in mosquito coil smoke (Lofroth et al., 1991).