Chemical Agents

By U.S. Department of Health and Human Services

Posted 3/29/06

Basic Facts

This section discusses four major types of chemical agents, grouped according to how they affect the human body:

Other categories of chemicals include:

For more information on these other chemical categories visit www.bt.cdc.gov.

Chemical agents can come in the form of poisonous gases, liquids, or solids.
These agents are usually fast acting and toxic to people, animals, or plants. (Note: A major exception is mustard agents, for which symptoms appear several hours after exposure.)
Poisoning by chemicals is not contagious. However, if residual chemical agents or vapors are on the skin, clothing, or hair or in biologic fluids (such as vomit), others can be exposed and affected. Once the agent is removed (e.g., by removing clothing and showering), the illness caused by a chemical agent cannot be spread.

Assessing the Risk

Because certain chemical agents are used in industry and household products, they are highly available.
After an outdoor release, the dangers associated with many chemical agents decrease over time because the chemical gets diluted as it spreads over a given area.
Terrorists could be minimally skilled to launch a limited chemical attack. A more widespread attack would require more expertise.
How lethal an attack is depends on several factors, including amount and type of agent used, route of exposure, time elapsed before decontamination, and access to medical care.

Chemical Agents as Weapons

Sufficient quantities must be used for chemical weapons to be effective.
Weather factors have an impact on the effectiveness of an open-air release. These factors include:
Temperature
Wind speed and direction
Humidity and air stability
Chemical agents are typically more deadly in confined or crowded areas, such as buildings, subways, or battlefields, where evacuation options are limited.
Chemical agents can be deployed in five ways:
Spraying the chemical with wet or dry aerosol sprayers (e.g., crop dusters, handheld spraying devices)
Using a heat source to vaporize the chemical for release
Using an explosive device to disperse the chemical
Pouring the chemical on a specific site (e.g., building floor, sidewalk, subway platform)
Contamination of food, water, or pharmaceuticals (such as the 1982 intentional contamination of acetaminophen products with cyanide)

Identifying an Attack

A chemical release may result in environmental clues, including:
Dead plants, animals, or insects
Pungent odor
Unusual clouds, vapors, or droplets
Discoloration of surfaces
Some common immediate physical symptoms from an airborne attack may include:
Tightness in chest and difficulty breathing
Nausea and vomiting
Watery eyes and blurry vision
A chemical attack is different from a biological attack in the following ways:
It is often an easily identifiable incident (e.g., chemical release from a fire at an industrial manufacturing facility).
Signs and symptoms appear rapidly after exposure (usually within minutes).
Victims are not contagious, although rescue workers can become ill if there is still residual chemical on the patient's clothes or skin, or in biologic fluids, and they are exposed to these agents without proper personal protective equipment (e.g., gloves and masks).

Lessening the Impact of Exposure (to Chemical Agents in General)

Follow the instructions of emergency workers, if possible.
Move away from the site of release (if known) during an outdoor release or go indoors.
Take shelter in place if you are indoors near an outdoor release.
Evacuate the affected building during an indoor release.
If you've been exposed to an agent, remove contaminated clothing and place in a plastic bag.
Wash with soap and water (when appropriate).
Flush eyes with water (when appropriate).
Seek medical attention if you have breathed in chemical fumes or if chemicals have touched your skin.
Patients should be decontaminated if they have chemicals on their clothes and/or skin (when appropriate).
If medically indicated and available, get appropriate antidote(s).
Consider using protective masks and clothing to minimize exposure.
Whenever possible, get emergency personnel in protective gear to assist in the removal of contaminated clothing.

Instructions for Sheltering in Place and Sealing After a Chemical Incident

If you have been exposed:

Remove contaminated clothing if coming from outside and seal it in a plastic bag.
Shower and wash with soap, if possible.
Find a room with as few windows and doors as possible.
Go to the highest level possible.
Turn off the air conditioner, heater, and fans.
Close the fireplace damper.
Fill sinks and tubs with water.
Turn on the radio for instructions.
Keep a telephone handy.
To seal the room, tape plastic over windows and doors; seal with duct tape. Tape over vents and electrical outlets (and any other openings). (Within a few hours, the plastic and tape may need to be removed to allow fresh air to enter the room to prevent suffocation. Follow the instructions of emergency workers and/or public health officials.

Shelter-in-place supply list (maintain enough for three days; check supplies every six months)

More information on disasters and emergencies is available at the U.S. Department of Health and Human Service's website: http://www.hhs.gov/emergency