Respiratory and Cardiovascular Medical Emergency Calls Related to Indoor Heat Exposure through a Case-Control Study in New York City.

Understanding when and where heat adversely influences health outcomes is critical for targeting interventions and adaptations. However, few studies have analyzed the role of indoor heat exposures on acute health outcomes. To address this research gap, the study partnered with the New York City Fire Department Emergency Medical Services. Paramedics carried portable sensors that passively measured indoor temperatures at 3-min intervals while responding to calls during summer, 2016. Patient care reports provided the patient's chief health complaint and sociodemographic and health status information. Propensity score matching increased comparability between groups exposed to elevated indoor temperature versus those unexposed. To assess indoor heat-health associations, we conducted independent case-control studies between indoor heat exposures and cardiovascular (n = 735) and respiratory (n = 296) emergency medical calls when compared to heat-insensitive controls (n = 1611). Patients experiencing heat exposures (indoor temperature ≥ 28 °C) were not significantly more likely (OR, 1.15; 95% CI, 0.64-2.09) to receive care for respiratory conditions. Both outdoor and indoor temperatures increased the odds of receiving care for cardiovascular versus comparison calls. Outdoor temperatures consistently elevated cardiovascular risks (OR, 1.12; 95% CI, 1.05-1.19). There was some evidence that indoor temperatures further increased the odds of cardiovascular distress (OR, 1.44; 95% CI, 0.97-2.13). Sensitivity testing suggested indoor temperatures at a lower threshold (≥ 26 °C) were unrelated to either health outcome. Along with converging lines of evidence linking extreme heat to adverse cardiovascular outcomes, we present one of the first indoor heat observational studies.