Fumigation is a method used worldwide to sterilize soil and to protect foodstuffs and other products against pests and diseases. The chemicals used are volatile, highly toxic pesticides, called fumigants, which in addition to their effect on pests also are toxic to humans. When fumigating an object, a gas tight cover is placed over it and thereafter the space is filled with toxic gas. Freight containers and cargo are fumigated before export in order to protect the cargo from being damaged during transportation and to avoid organisms from spreading to other countries. The gas is expected to diffuse off and disappear to the atmosphere after the fumigation process is over, but often there are high concentrations of gas left when the cargo has reached its final destination and are to be unloaded. This has led to problems for personnel within the Swedish Customs and the Coast Guard, who, at the inspection of cargoes, may have been exposed to high levels of fumigation chemicals. Stock workers at several major importing companies have, while handling and unpacking goods, also experienced symptoms of fumigation chemical poisoning. A variety of instruments for detection of gas are available on the market today, but they often face problems in the detection of one or several fumigants. These chemicals have very different physical and chemical properties, which make the conditions for detection very different.