Background Indoor air quality directly affects people's health, especially the impact of chemical pollutants in residential indoor air on children and the elderly is more significant.

Objective To understand the pollution status of common chemical pollutants in residential indoor air in Shijiazhuang, evaluate the health risks of chemical pollutants to school-age children and the elderly, and provide reference for controlling indoor pollution in residential environment.

Methods Using stratified random sampling, a total of 60 households were selected from 2 urban areas and 1 surrounding rural area in Shijiazhuang City, specifically in July 2023 (non-heating season) and December 2023 (heating season), respectively. Relevant data was collected through on-site sampling including CO, CO₂, PM₁₀, PM_2.5, NO₂, SO₂, O₃, ammonia, formaldehyde, benzene, toluene, xylene, total volatile organic compounds (TVOC), trichloroethylene, and tetrachloroethylene and survey questionnaires. The pollutant concentrations were evaluated following the Standards for indoor air quality of GB/T 18883-2022, and the inhalation exposure risks of the target population were assessed based on the health risk assessment method.

Results In the indoor air of the urban and rural residence in Shijiazhuang City, except for CO, NO₂, SO₂, toluene, and xylene, which did not exceed the standard limits, other pollutants showed varying degrees of exceedance. The non-qualified rates of PM₁₀, PM_2.5, and CO₂ in the urban areas were higher than those in the rural areas (P < 0.05). The seasonal difference analysis showed that the non-qualified rates of PM_2.5, PM₁₀, CO₂, trichloroethylene, and tetrachloroethylene in the urban areas were higher in the heating season than in the non-heating season (P<0.05); the non-qualified rates of ammonia and formaldehyde in the rural areas increased significantly in the non-heating season(P<0.05). The health risk assessment indicated that the maximum hazard quotient (HQ) of tetrachloroethylene for the elderly exceeded 1, while the HQ values for ammonia, formaldehyde, benzene, toluene, xylene, and trichloroethylene remained below 1 for either children or the elderly. For carcinogenic risks, the median carcinogenic risk (CR) of formaldehyde for school-aged children or the elderly fell within the range of 10⁻⁶-10⁻⁴, whereas the median CR values for benzene, trichloroethylene, and tetrachloroethylene were all below 10⁻⁶.

Conclusion The primary indoor air pollutants exceeding the national standard limits in residential areas of Shijiazhuang City include CO₂, PM₁₀, TVOC, PM_2.5, formaldehyde, ammonia, trichloroethylene, and tetrachloroethylene. The levels of these pollutants exhibit significant urban-rural and seasonal variations. Special attention should be paid to the non-carcinogenic risk of tetrachloroethylene to the elderly and the carcinogenic risks of formaldehyde to school-age children and the elderly.