Although no one appears to have been killed by the initial Iraqi missile attack on Israel early yesterday, at least three people were reported to have suffocated after failing to remove a cap on the breathing canisters of their gas masks, according to Israeli civil defense authorities.

Dozens more were taken ill after prematurely injecting themselves with a nerve gas antidote. The Israeli government supplied the antidote and gas masks to most of the country's 4.6 million citizens.

The accidental deaths and premature injections illustrate the panic that ensues when people fear that nerve gas might be used. It was not used in that Iraqi attack, although the Scud missiles in Iraq's possession can be equipped with chemical warheads.

A spokesman at the Israeli Embassy here said that those who died were elderly people who failed to remove a plastic cap on the filters of their gas masks. Even though they found themselves suffocating, the Israeli spokesman said the victims were probably too panicked to remove the masks.

"It sounds to me like they put canisters on gas mask and did not remove the sealing device," said one U.S. manufacturer of gas masks. "With the seal on, you couldn't draw air in. You'd suffocate."

Dick Miller of Mine Safety Appliance Co. in Pittsburgh, another manufacturer of gas masks for U.S. troops, said soldiers are trained in use of masks because of the possibility of such accidents.

"The first time you put on a gas mask can be very frightening experience," said Elisa D. Harris, a senior research analyst and chemical weapons expert at Brookings Institution here. "You can feel panicky and claustrophobic."

"It takes some training and some presence of mind to use these masks properly," said Richard Dewey of the Chemical Research, Development and Engineering Center at Aberdeen Proving Ground, Md., where gas mask have been developed.

An embassy spokesman here said the Israelis were given rudimentary instruction in use of gas masks and television also carried instructions.

The first warning of the Friday attack came when Israel radio interrupted its 2 a.m. news broadcast. Sirens wailed and Israelis were ordered into their "safe" rooms and told to don their gas masks.

In preparation for attack, Israelis were told to seal windows of one room with plastic and tape to keep out nerve and mustard gas in case of attack. After the sirens sounded, Israelis gathered in their safe rooms, put on gas masks and placed wet towels at the bottom of the door.

Iraq is believed to have stores of at least two types of nerve gas: tabun and sarin. Chemically related to pesticides, tabun and sarin kill by meddling with metabolic processes and causing a buildup of a key chemical messenger in the human body called acetylcholine, which operates in the gap between nerve and muscle cells.

A buildup of acetylcholine may cause drooling, excessive sweating, cramping, vomiting, confusion, irregular heartbeat, convulsions, loss of consciousness and coma. A single, deep inhalation of sarin can bring death in 10 minutes.

Iraqi President Saddam Hussein's forces may also have another nerve gas known as VX, according to Harris of Brookings.

Depending on weather and wind, dangerous levels of tabun may linger as long as a day or two; sarin may last for minutes to hours. According to Harris, VX can linger for weeks. The area in which the gas is effective is reasonably small and those exposed are usually moved quickly, meaning they would not have to keep gas masks on for long.

Iraqi forces may also possess mustard gas, which burns the skin, throat and lung linings.

Gas mask filters scrub the air wearers breathe. The paper, carbon and various metals in the filter absorb the incoming droplets and vapors of nerve gas.

In case they are contaminated by nerve gas, U.S. soldiers in the Persian Gulf region and Israeli citizens have also been provided needles to inject themselves with a nerve gas antidote called atropine. Atropine counteracts the gas by stopping acetylcholine from building up in the gap between nerve and muscle cells.

If the atropine is administered when a person has not been exposed to nerve gas, it can cause symptoms such as a racing heart, anxiety and hallucinations that doctors compare to the effects of taking too much cold medicine.

Staff writer William Claiborne in Tel Aviv contributed to this report.

At least three Israelis suffocated using gas masks during an Iraqi missile attack early Friday morning. Apparently they failed to remove a cap that seals and protects the charcoal filter when it is not being used.

Canister on mask contains charcoal, which reduces almost to zero the concentration of chemicals in the air.

Screen removes larger particles.

Filter removes aerosols and smoke. Compiled by James Schwartz -- The Washington Post