Hundreds of first responders have told me they remember exactly how they felt during the World Trade Center attacks, even 25 years on.They tell me that they remember not being able to think, see or smell anything. They could focus only on digging and pulling debris out of the way. They could not rest because those trapped beneath the rubble could not wait. Death was all around them, and they could only do as much as they could to hold it back.While what happened on 9/11 was unprecedented, similar tragedies happen quite frequently. As a physician in occupational health who works with 9/11 first responders, I can easily imagine those same thoughts from other firefighters, paramedics and construction workers trying to save lives after the deadly summer 2026 earthquakes in Venezuela, Colombia and Indonesia or the disastrous floods in Nepal.These first responders may also need to recover human remains from the rubble. Surrounding these moments of intimate grief are dust, toxic fumes and cries for help. And this trauma takes a toll.Whether it’s industrial or nuclear disasters, extreme weather, wildfires, volcanic eruptions, war or terrorist attacks, first responders and affected communities can experience significant physical and mental health effects both during rescue and recovery operations and for years afterward. All are vulnerable to mental and physical harm no matter how well trained they may be.Research from my team suggests that among these risks is post-traumatic stress disorder that may cause their brain to age faster. People gather by a reflecting pool during a memorial on the 25th anniversary of the 9/11 terrorist attacks on September 11, 2026 Nearly 3,000 people died in the 9/11 terror attacks in 2001