Objective To conduct an exposure factor investigation related to the physical characteristics, intake, and time-activity patterns of the population around a site, with a coking plant in Shanxi province, China as an example, and to provide data support for regional environmental health risk assessment.

Methods The investigation was conducted from April to May 2021. A primary school and a middle school were randomly selected by lottery within 5 km around the coking plant. Based on stratified cluster sampling, two or three classes each were selected from all grades of the schools, and the selected students' family members (usually resident within 5 km around the coking plant for more than half a year) were surveyed by questionnaires to obtain the exposure factors. The results were compared with the national and international recommended values of relevant exposure factors.

Results A total of 892 participants were investigated, including 445 males and 447 females. The mean body weights of male and female adults were 70.1±9.3 and 60.5±8.8 kg, respectively. The mean skin surface areas were 1.78±0.12 and 1.59±0.12 m², respectively. The mean long-term inhalation rates were 17.6 and 14.3 m³/d, respectively. The mean outdoor activity time on working days and rest days was 225 and 210 min/d for adult men, respectively, and 165 and 180 min/d for adult women, respectively. Adult men had significantly higher values of mean body weight, skin surface area, long-term respiratory capacity and outdoor activity time than adult women (all P < 0.05). The mean body weight(F=248.98), mean long-term inhalation rates(χ²=176.06), drinking water quantity(χ²=7.35), indoor activity time(χ²=36.30), outdoor activity time(χ²=36.30), bathing time(χ²=31.16), and soil-dust contact time(χ²=12.37) between different age groups had a significant difference(P < 0.05).The adult population in the surveyed area showed higher values of physical characteristic factors and lower values of intake factors than the national average levels. The results of adults' time-activity patterns in the surveyed area, including indoor and outdoor activity time, bathing time and swimming time were different from national and international data.

Conclusion The survey obtained the exposure factors of a representative population around an actual site, which provides data support for the future health risk assessment of populations in the vicinity of the site.