BAGHDAD — For the second time in two days, suspected Sunni Arab insurgents Wednesday targeted civilians with a crude chemical weapon: a bomb attached to chlorine gas canisters that killed two people, sickened 25 and injured eight others.
The attack was the third in a month involving a combination of explosive devices and chlorine. Though all three attacks were apparently botched, they hint at an ominous new tactic being cultivated by insurgents to subvert a U.S.-Iraqi security crackdown in Baghdad.
Violence around the country left at least 40 other Iraqis dead. An American soldier was reported killed in a small-arms fire attack a day earlier in Baghdad, and a U.S. Black Hawk helicopter was forced to make a hard landing Wednesday north of the capital amid reports of ground fire, the military said.
The chlorine gas attack took place on the road leading to Baghdad's airport. A car filled with chlorine gas cylinders exploded near a fuel station in a religiously mixed neighborhood.
The tactic was used the day before in Taji, north of Baghdad, when insurgents detonated a truck holding two chlorine gas tanks. Six people were killed, and scores more suffered nausea, vomiting and irritated eyes.
A suicide bomber also plowed a dump truck filled with explosives and a chlorine tank into the base of a rapid-reaction force near Ramadi on Jan. 28, killing 16 people. "There are no indications of any casualties caused by the release of chlorine gas," the U.S. military said at the time.
The use of chlorine gas weapons in warfare dates back at least to World War I, when Germans first used them in April 1915 to dislodge French soldiers from trenches. The weapons caused far more injuries than deaths.
Chlorine can burn the eyes, nose and throat and cause dizziness, nausea and vomiting. In higher doses -- a few breaths at a concentration of one part per thousand -- it can damage enough lung tissue to be fatal.
Chemists said that exploding high-pressure canisters are at best a crude way to disperse the green gas. Some would burn off, and the rest of the gas, which is heavier than air, would be unlikely to spread much beyond the blast zone.
Stephen Bradforth, a chemistry professor at USC, suggested that the most serious damage could be psychological.
An explosion "would launch a cloud of gas that is colored and highly corrosive and would lead to panic and more injuries," he said. "It's the chemical equivalent of a nail bomb."
