Abstract:In Guangdong province, many hot springs were exploited and developed into popular places for tourist. In addition, hotels have been set up near hot spring sites to attract people, including local citizens, to spend their spare time inside these so-called "spring hotels". In our study, indoor air quality was investigated in four hot spring hotels in Guangdong province, China. Measured indoor pollutants included CO 2 , CO, PM 10 , PM 2.5 and Volatile Organic Compounds (VOCs). As the result show, high concentrations of carbon dioxide might be attributed to poor ventilation; and the variations of indoor PM 10 , PM 2.5 concentrations were related to occupants' activities. Alpha-pinene and toluene were the most common VOC species in the hot spring hotels other than monocyclic aromatic hydrocarbons like Benzene, Toluene, Ethylbenzene and Xylenes (BTEX), which were at medium levels among the reported indoor pollutants. High cancer risk of benzene in the newly decorated rooms should be seriously taken into consideration in the future. Indoor to Outdoor air concentration ratios (I/O) for CO 2 and VOCs were higher than 1, indicating their strong indoor sources. Negative correlations were found between indoor CO 2 and all the other compounds, and VOCs were shown to be significantly correlated (p < 0.01) to each other, including aromatic hydrocarbons and mono-terpenes. For indoor and outdoor air compounds, correlation coefficients among all compounds did not show a significant correlation, which indicated that these pollutants had different sources. Principal components analysis by SPSS showed that indoor materials, inhabitants' activities and respiration, cleaning products and outdoor sources were the main sources of indoor detected pollutants in hot spring hotels.