The US government will install explosives detection trace portal machines at five more airports by the end of May to enhance airport security, the Transportation Security Administration (TSA) announced Friday.

With these five airports -- Miami International, San Francisco International, Phoenix Sky Harbor International, Boston's Logan International, and Los Angeles International, the TSA will have trace portals installed in 14 airports by the end of May this year.

The TSA began the pilot program in summer last year, by starting field testing trace portals at passenger security checkpoints at five airports. The machines were installed in five other airports in the fall last year.

Under the program, select passengers will be directed by the TSA screeners to step into the trace portal. The portal detects explosives by blowing several "puffs" of air onto passengers, and air samples are then collected and analyzed for explosives. If the portal alarms, passengers would have to go through additional screening.

The pilot program was scheduled to continue through early summer to provide the necessary data for future expansion, said David M. Stone, assistant secretary of homeland security for the TSA.

The TSA began another pilot program last year, by deploying an explosives trace detection document scanner at several airports. The scanner can "sniff" passenger documents such as boarding passes and drivers' licenses for traces of explosives, and alerts the screener if explosives residue is detected.

Source: Xinhua