GAS MASKS

Eight Scud-B missiles from Iraq--all high explosives rather than the feared poison-gas type--struck Israel early Friday. A dozen Israelis were hurt. But tragically, three women and a 3-year-old child suffocated in their gas masks during the raid. Most of the victims apparently had failed to remove the cap on the breathing canisters of their government issued gas masks.

Different kinds of masks are used in different nations; the U.S. military offers three main types:

M17 A1 is used by the infantry. It has small eyelets. The filter, inside the cheek pouch of the mask, is good for about 24 hours before filling with dust.

M43 is used in helicopters. It allows Apache pilots, in particular, to wear their special sighting system gear and the mask at the same time. The M43 also is attached to a ventilator which blows in fresh air.

M25 A1 is used by tanks and armored vehicles. It is similar to the M17 and is also connected to a breathing unit. It has a wider face cover than the M17 so that the vehicle operators have far better visibility.

Ideally, masks are fitted to the individual wearer to avoid readjustment in the 13 seconds required for putting them on. Masks are put on like catcher’s masks, then attached by four straps. A wearer needs to blow into the canister to clear it, then breathe normally.