The threat of homemade explosives (HMEs) is not new. Events after 9-11 such as the "shoe bomber" in 2001, the London Underground bombings in 2005 and the "underwear bomber" in 2009 re-emphasized the threat and the need for a strong program to detect these new threats.

As these threats are often made of common commercial items, it is a challenge to distinguish true HME threats from the many innocent gels and liquids in personal baggage or cargo. The HME Characterization Program examines the chemical and physical properties of these explosives in order to support the development of new screening technologies. The program is developing decision support tools for responders to help mitigate HME incidents and respond more efficiently and safely. EXD has also made it a priority to develop standard procedures for the safe handling of HME threats. This baseline data allows EXD to work with its partners at universities and in industry to develop systems that will screen for a broader range of threats to the travelling public.