Methods Different high risk sites were selected by stratified random sampling,and uniform questionnaires about health and other factors of the FSWs were filled.

Research analyses of explosive parameters in hazardous area for powder and explosive materials;

Release source,including the nature of flammable substances,the characters of the release sources,the characters of the ignition resources,mode of the systems operation and the environmental factors are the essential factors affected to the classification of the hazardous areas.

The potential risks and dangers have mainly been analyzed of using the ordinary mobile telephone in the hazardous location, thus, it reminds people to use the Ex mobile telephone or to turn off the ordinary mobile telephone.