Dr. Nir Greenberg

The 2025 Southern California wildfires were among the most severe natural disasters in recent U.S. history, leading to mass evacuations and a massive emergency response. This retrospective cohort study aims to understand how first responders (FRs) across the U.S. expressed and managed their emotions and communications during the crisis, by analyzing their activity on X (Twitter). We identified 338 U.S.-based FR accounts using regular expressions and manual verification, and constructed a matched control group of 6061 U.S.-based non-FR accounts based on account-level features using KDTree similarity and statistical validation. To analyze patterns of emotion, discourse, and attitudes toward authorities, we performed multimethod analysis consisting emotion classification, topic modeling, and prompt-based evaluations. Our results indicate that FRs exhibited consistently higher levels of fear and lower levels of joy compared to non-FRs, suggesting possible secondary traumatic distress - even among those not directly involved in the emergency response efforts. The discourse analysis showed that FRs focused on professional responsibilities and operational risks, reflecting an extension of their occupational identity into the digital sphere. Unlike non-FRs, FRs were more critical of political leadership but more supportive of operational agencies such as CAL FIRE and FEMA. Post-crisis data showed a narrowing of the emotional gap in joy, possibly reflecting adaptive resilience and a sense of mission accomplishment. These findings highlight the psychological impact of the crisis on FRs and show how social media can supplement traditional mental health assessments by providing aggregated distress-related signals when real-time evaluation is impractical.