One hundred and thirty-five participants (67 males and 68 females) were recruited and tested to obtain respiratory rates, showing the median values of respiratory rates were 11.7 m3/day and 14.0 m3/day for subjects aged 6-18 years (n = 100) and 41-50 years (n = 35), individually for the resting condition. As for showering condition, the median values of respiratory rates were 14.7 m3/day and 17.0 m3/day for subjects aged 6-12 years and 41-50 years, individually. It was shown that the current default values of respiratory rate during resting (15.8 and 15.32 m3/day for children and adults, respectively) and showering (13.9 and 24 m3/day for children and adults, respectively), recommended by the Environmental Management Administration Ministry of Environment, could be overestimated. Additionally, 60 participants (29 males and 31 females) aged 31.5 ± 8.6 years were recruited to wear the accelerometer on non-dominant wrists and waists to obtain the metabolic rates under different physical activities with various intensities. Results from the accelerometer worn on waists indicated the proportion of time contributed by the light physical activity (LPA) and the moderate-to-vigorous physical activity (MVPA) were 97.0% and 2.9%, individually. In most subjects evaluated in this study, sedentary behaviors were more frequent than the more health-beneficial moderate-to-vigorous physical activities. The metabolic equivalents (MET) measured by the accelerometer were plugged into the equation proposed by Layton (1993), estimating the median daily inhalation rate (DIR) at 13.3 m3/day (16.9 and 11.3 for males and females, respectively). Notably, the athletes and polices have significantly higher DIR than those of other subjects due to their higher physical activities. This study also reviewed the relevant literature on the types and wearing conditions, the seal leakage and penetration rate, and the filtration efficiency and protection factor of hazards of respiratory protective equipments (RPEs) used in the contaminated sites. Moreover, we interviewed the on-site workers to investigate the actual wearing conditions of RPEs in a polluted area, showing that they mainly wore the essential protective equipment, i.e., disposable masks, long sleeves, trousers, sun protection accessories, gloves, and safety shoes. On-site workers also noted that they would temporarily remove the RPEs due to sweating during high-intensity activities. Therefore, because they would not always wear RPEs during work, on-site workers might be exposed to the inhalation risk of harmful substances for a short time. According to the results of expert meeting discussions, it is recommended that the protective efficiency of RPEs is more suitable for protecting particulate matter (PM) in heavy-metal-contaminated sites than for those contaminated by oil products or volatile organic compounds (VOCs). For the localized parameters of respiratory rate relevant to the targeting objects of this project, it is suggested that the default values of first-level health risk parameters be set according to the upper bound of the 95% confidence interval. In that regard, the upper bound of the 95% confidence interval of the respiratory rates for children and adults during resting conditions were 13.2 and 13.5 m3/day, respectively, while those during showering were 16.1 and 15.8 m3/day, respectively.

health risk assessment, inhalation rate, respiratory protective equipment, risk conversion coefficient, receptor exposure factor