Nontoxic Gas Test Near Pentagon to Aid Defense Against Attacks

WASHINGTON — The military will release an invisible nontoxic gas into the air around the Pentagon in the coming weeks as part of an effort to develop defenses against a chemical or biological attack, officials said Monday.

The release of the odorless sulfur hexafluoride, expected over a three-day period in early May, will allow sensors to trace its flow in and around the building, the Pentagon said in a statement. By studying how it circulates through the Pentagon’s air system, experts will be able to simulate how a chemical or biological weapon might spread during an attack on the building.

The study will include the launch of a 30-foot-long blimp in the Pentagon’s parking lot. It will fly mostly at night and measure wind speeds around the building.

The exercise, called “Pentagon Shield,” will aid development of an advanced chemical and biological protection system for the Pentagon and its occupants, the military statement said. The Pentagon said the gas was safe and frequently used in airflow testing.