Urban exposures, frailty, and mental illness in World Trade Center Health Program responders

General responders of the World Trade Center Health Program were uniquely exposed to chemical toxicants and extreme psychological stress during the 2001 terrorist attack, and now experience unusually prevalent health outcomes for a mid-aged population, including frailty, Post Traumatic Stress Disorder, and depression. We study whether these conditions are linked to later-life urban environmental exposures among 18,734 responders, evaluating associations with annual fine particulate matter, temperature, and Green View Index. A decile incremental increase in the overall exposure-mixture is associated with increased frailty (0.56%; 95% CI: 0.14%;0.98%) and Post Traumatic Stress Disorder scores (0.31%; 95% CI: 0.07%;0.55%). Effects are more pronounced among responders with higher World Trade Center exposures, suggesting increased vulnerability. Here, we show that urban environmental exposures compound the chronic health burden in World Trade Center responders, with effects possibly amplified by World Trade Center exposure history. This suggests that a history of trauma and toxicant exposure can create lasting biological vulnerability to subsequent environmental stressor.