The best defense that thousands of Iraqi Kurds have against a lethal gas attack is a homemade hood of vinyl, cotton and charcoal, tied tightly around their necks with a shoelace.
No government or aid agency answered the Kurds' call for gas masks, even used ones with basic supplies to refurbish them. The few imported masks in the local bazaar were sold out a month ago.
So a team of Kurdish scientists came up with a cheap alternative that it says will save lives if Saddam Hussein's forces attack the Kurds with gas as they did in the late 1980s.
Materials for the masks are easily found around the home or in the nearest market. When assembled properly, they make a device that "is chemically and scientifically proven effective," said Wishyar Ali Ismael, head of the Chemical Experts Union.
The masks probably are only 80% as effective as those manufactured abroad, Ismael acknowledged.
But without filtered hoods, most Kurds would have no better defense against chemical or biological weapons than a damp cloth and a prayer.
In 1987 and 1988, Iraq launched more than a dozen chemical weapons attacks on Kurdish villages in northern Iraq, local scientists say.
The most notorious attack on the Kurds, whom Hussein accused of siding with the Iranians during the Iran-Iraq war of the 1980s, killed 5,000 in Halabja on March 16, 1988.
A minor panic struck Irbil on Friday morning when a blast sent a thick plume of white smoke billowing high above a neighborhood on the city's outskirts.
Hiwa Tayful, 30, was selling gasoline from plastic containers at his makeshift filling station when a shell exploded about 30 yards away at the edge of a garbage dump.
"I just dropped face down on the ground," he said later. "I thought that it was the [ruling] Baath Party bombarding the area. I was terrified that it was poison gas, frightened to death when I saw smoke. It was white as snow."
No one was injured in the explosion, but Karim Sinjari, the regional government's interior minister, called it an attempt to terrorize people by mimicking a gas attack.
"Whoever was behind the terrorist attack wants the most negative effect to show people it is possible to have a chemical attack," Sinjari told reporters.
Local police and scientists were investigating the incident and there was no immediate evidence that the shell contained anything more than regular explosives and "a lot of smoke material," Sinjari added.
Police found a second artillery shell nearby that had not exploded, Sinjari said.
Tayful said he had never heard of a homemade gas mask, although the regional government has sponsored radio and television spots that give detailed instructions on how to make one. The government started pushing the idea only a few weeks before the war began, even though the scientists union had been trying to get the campaign started for more than a year, Ismael said.
"They didn't want to panic people," he said of the regional government.
The union has made about 3,000 masks and an unknown number of people have taken up the call and made their own, Ismael said.
The scientists came up with the concept by taking apart Iraqi army gas masks imported from the former Yugoslavia. The tight-fitting rubber masks, with glass eyepieces, have activated charcoal filters in metal canisters that hang from the front.
The Kurdish version is a loose hood of vinyl upholstery material, with a clear plastic window and a sealed packet of home-baked charcoal sewn to the front. It costs less than $7 to make, Ismael said.
The key ingredient is 150 grams of charcoal, the amount the scientists found in the Yugoslav gas masks. The charcoal is ordinary burnt wood, crushed into bits about the size of coffee grounds and heated in a kitchen oven at high temperatures for about an hour.
Once the charcoal has cooled in the open air, it is folded in soft cotton cloth, which is sewn onto the front of the vinyl hood, with breathing holes poked through the material.
The cotton blocks the killer smoke, while the activated charcoal absorbs any vapor that gets through, Ismael said.
A shoelace pulled tightly around the neck is supposed to keep gas from seeping in. It's not perfect, Ismael acknowledged, but it's better than nothing.
By studying the effects of mustard gas on survivors of attacks, the Kurdish scientists found that those who had covered their faces with wet cloths suffered serious blisters only on the uncovered parts of their heads.
The homemade masks give people at least a fighting chance to get out of an area contaminated by chemical or biological weapons and to a safe zone, Ismael said.
But they do have one defect, he admitted. It's a lot harder to breathe in the homemade masks because they don't allow air to pass in and out as easily as the commercial models do.
Although Iraqi Kurds have suffered the worst of Hussein's poison gas attacks over the years, the scientists union doesn't think the Iraqi president's regular troops will use the weapons against the Kurds during this war.
Terrorists are the real threat now, Ismael said.
"He no longer has the ability to attack us with chemical weapons from a distance," Ismael said. "But within 24 hours, he can create poison gases and he could send them with someone in a can.
"He is a criminal. We expect everything bad from him."