Air pollution is associated with elevated HPA-Axis response to stress in anxious adolescent girls

Research suggests that exposure to fine particulate air pollution (PM2.5) increases hypothalamic-pituitary-adrenal (HPA) axis activation in adults; it is unclear, however, whether PM2.5 is associated with HPA-axis functioning in psychosocial contexts, such as during the experience of social stress. One recent study of adolescents found that PM2.5 was associated with heightened autonomic reactivity to a social stress task, and that this association was strongest for adolescents with more severe internalizing symptoms. Here, we sought to replicate and extend these findings to HPA-axis stress responsivity in an independent sample of adolescent girls (N=130). We estimated PM2.5 concentrations at each participant’s address using data from nearby air quality monitoring stations, and assessed participants’ anxiety symptoms. We measured salivary cortisol in response to a social stress task and characterized HPA-axis functioning by computing area under the curve with respect to ground (AUCg) and with respect to increase (AUCi). Controlling for demographic factors, we found that PM2.5 was associated with heightened HPA-axis stress responsivity (both AUCg and AUCi) for girls who reported more severe levels of anxiety. We did not find a main effect of PM2.5 on HPA-axis functioning. These findings suggest that anxious adolescents are particularly vulnerable to the adverse effects of PM2.5 exposure on biological sensitivity to social stress.