Our study examined the associations between WTC exposures and COVID outcomes using two analyses: one focused on COVID severity and the other on post-acute sequelae of SARS-CoV-2 infection (PASC), which is known as long COVID. In the severity analysis, our aggregate exposure measure revealed that a significant portion of the effect on COVID severity is mediated by obstructive airway disease (OAD), indicating that impaired respiratory health is a key pathway linking WTC exposures to more severe acute illness. In the PASC analysis, we found that the overall effect of WTC exposures on long COVID is largely mediated by impaired respiratory health. These findings suggest that while OAD is a critical mediator for both COVID severity and PASC, additional mechanisms likely contribute to long-term outcomes.