Emergency
112European emergency 117Police 118Fire brigade 144Ambulance 1414Rega (air rescue) 145Tox Info (poisoning)
Local time
Guide · GUIDE 18

Protection in a chemical accident

Last reviewed on 29.06.2026

A chemical or industrial accident («major accident») releases dangerous substances – toxic, flammable or explosive gases and liquids. The main danger is a spreading cloud of pollutants. Unlike many hazards, the protective rule here is not «out» but «in»: anyone who reaches a building, closes windows and doors and switches off the ventilation is much better protected than outdoors.

Current situation: check the situation dashboard to see whether any warnings are currently in effect for this hazard.

What do I do during a chemical alarm?

  1. Get into the nearest building immediately, close windows and doors
  2. Switch off ventilation and air conditioning
  3. Move to higher rooms (many gases are heavier than air)
  4. Switch on the radio (SRG/FM/DAB+), follow Alertswiss, wait for instructions
  5. Take neighbours and vulnerable people into the building

Before: prepare

  1. Know: on a chemical alarm, get inside – not outside
  2. Keep a battery radio (FM/DAB+) and the Alertswiss app ready
  3. Know which rooms can be sealed well (few windows)
  4. Recognise the general alarm of the siren (rising/falling, 1 minute)

After: wait for the all-clear

  1. Only ventilate and go outside once the authorities give the all-clear
  2. Handle contaminated clothing/objects according to instructions
  3. In case of irritation of eyes, airways or skin, seek medical help

What equipment do I need for a chemical accident?

The most important things are a network-independent information channel and a sealable room – not expensive protective gear.

  1. Battery/crank radio (FM/DAB+) with spare batteries, Alertswiss app
  2. Tape and damp cloths to temporarily seal window/door gaps
  3. Drinking water and some food for the time in the sealed room
  4. Charged phone and power bank
  5. Know which interior room is best suited (interior, few windows)

Common mistakes

  1. Going outside or driving to the accident site during a chemical alarm
  2. Leaving the ventilation/air conditioning running and drawing in pollutants
  3. Leaving windows open or going to «take a look»
  4. Constantly using the phone instead of keeping it free for emergency calls
  5. Ignoring the general alarm or not switching on the radio

Frequently asked questions

What should I do during a chemical or major accident nearby?

Go indoors, close windows and doors, switch off ventilation/air conditioning, listen to FM radio, follow Alertswiss. Leave the shelter only when the all-clear is given.

What does the General Alarm mean in this context?

A rising/falling wail of one minute (possibly repeated after 5 min): listen to the radio, follow instructions. In a chemical event, as a rule: go into a building and seal it.

Why should I stay indoors during a chemical accident rather than flee?

Closed rooms protect against airborne pollutants. Outdoors you expose yourself to the cloud. So: go in, seal up, get information until the all-clear.

Official sources