Soldiers and emergency personnel prepared to deal with chemical and biological weapons incidents need both specialist clothing and rigorous training.
Military-issue gas masks can protect against virtually all known chemical and biological agents.
They will only save the wearer's life if they are put on fast enough. Training involves learning to put the mask on in nine seconds. Masks are usually made of impermeable butyl rubber.
The view from inside a gas mask
A canister containing a filter - usually made of charcoal - absorbs particles from the air. The filter must be changed after a number of hours of exposure.
Masks make it harder to see, hear, talk, eat and drink.
Some have built-in drinking devices and can be fitted with lenses for people who wear spectacles.
A smaller mask covering only the mouth and nose can protect against inhalation of all biological agents.
Israeli civilians were issued with gas masks when Iraq attacked with Scud missiles during the 1991 Gulf War. Chemical weapons were not used, but seven people died as a result of not using the gas mask kits properly, according to the Israeli Defence Force.
In late 2002 gas masks were again being distributed in Israel. Iraqi civilians do not have access to gas masks.
Military NBC (nuclear, biological and chemical) suits can protect against chemical and biological agents for a limited period of time.
Together with gloves, boots and gas mask they take about five minutes to put on.
Heat stress and hypothermia are both risks
Suits are usually semi-permeable, with an outer cotton layer and an inner layer of charcoal-impregnated polyurethane foam.
This allows some flexibility and ventilation, while absorbing particles of chemical or biological agents in the charcoal to stop them reaching the skin.
Like gas mask canisters, a suit becomes ineffective after a certain period of exposure, depending on the form and concentration of the agent.
The suit is usually worn over ordinary clothing and slows down most activity. Heat stress and dehydration become problems in hot conditions and hypothermia is a risk in cold temperatures.
3. Gloves and boots
Totally impermeable butyl rubber boots and gloves are worn, giving full protection to the hands and feet but allowing no ventilation.
Overboots are pulled on over ordinary shoes, while the gloves are worn with an inner cotton lining pair to absorb moisture.
Gloves reduce dexterity, which is particularly an issue for soldiers required to do delicate tasks such as using a keyboard or operating communications equipment.
Forces also try to set up larger "collective protection" areas in buildings, vehicles, tents and parts of ships where individual protective clothing is not necessary.
These give soldiers a break from the stress and discomfort of wearing full body protection.