Jet Crash
You've probably heard that a F/A-18D jet crashed in San Diego on approach to Miramar, killing 3 on the ground (the pilot ejected and is fine). A lot of the news reports noted that ~20 homes were evacuated due to 'toxic chemicals'. What sort of chemicals would you be worried about?
First Responders and Bystanders
Beyond the physical hazards (things under pressure like hydraulics, O2 canisters,...etc), there's all kinds of stuff to worry about like fuel, oils, hydraulic fluids, beryllium, lithium, chromium, mercury, and possibly radioactive compounds. But the biggest hazard is simply the…