After a structural collapse, common household chemicals can result in a toxic environment.

The introduction of an ignition source may result in a fire or explosion. Eliminate ignition sources e.g. cigarettes, open flame light sources.

Hazardous materials in the collapse site or adjacent to it should also be considered. This could include materials stored on site or used in the construction and include:

* Asbestos
* Compressed gas cylinders
* Biological and radioactive materials
* Pesticides
* Cleaning agents
* Acids and oil
* Contaminated waste products
* Medical waste

The use of the structure will give you some information about the types of hazardous substances you may encounter. A collapsed fish and chip shop, for example, will probably have a lot of oil and gas for cooking.

Rescuers should avoid contact with all of the above substances and ensure that other rescuers are made aware of their presence.