Don’t make me out to be a liar. I teach safety classes to child care providers. In one of my classes I teach evacuation procedures and during this class I tell them about Sheltering in place. I tell them that they should only be evacuated during a chemical incident is if they are in the blast zone.

As a fire line officer it was always my idea that, if there is a chemical leak or incident that people need to be evacuated. As I researched my class I found that in many cases that is the worst thing to do. Why you may ask? When you’re evacuating people where are they going? From their home to another location and they need to go outside to do that and in many cases they are being exposed to the chemical.

Some items from a study of the National Institute for Chemical Studies;

Sheltering in place as a public protective action has received large amounts of attention as a result of the submission of Risk Management Plans (RMP). Although sheltering in place has been used by emergency management officials for many years, very little data have been collected on how it has been used and its effectiveness. Both supporters and critics alike have expressed interest in such a collection of data about sheltering in place.

Many, if not most communities in the United States are vulnerable to the health and safety impacts of a hazardous materials emergency. These types of emergencies can result from accidents that occur at a wide variety of places including industrial facilities, government and educational institutions, commercial establishments, farms, and during transport. When these events occur, emergency response officials have two basic tools to protect the threatened public. One is to evacuate the public out of the area affected by the hazardous material release. The other is to request that the public “shelter in place, “ that is, go indoors, close up the building and wait for the danger to pass.

Evacuation has long been used to move the public away from danger. Its goal in hazardous materials emergencies is to avoid or minimize exposure to dangerous chemicals. When evacuation can be completed before dangerous levels of hazardous materials move into the community, it is the public protective action of choice. This will avoid exposure to the hazardous material completely. It may also be preferable when the leak is large, unpredictable and difficult to control, or when there is a high risk of explosion or flash over. However, evacuations can take a very long time to complete, particularly in areas with high population density. And evacuating has inherent risks unrelated to the hazardous material. Managing an evacuation is a resource-intensive activity for local emergency management agencies.

(In a conversation with a emergency management agent I was told that it could take as long as 4 hours from the time the OIC says evacuate until the first person is walking into a shelter)

Shelter in place as a public protection tool has gained acceptance as a public protection tool. The goal of sheltering in place during hazardous materials accidents is to minimize the exposure of the threatened public to the dangerous chemical(s). Sheltering in place uses a structure and its indoor atmosphere to temporarily separate people from a hazardous outdoor atmosphere. The people will still be in the endangered area, but will be protected by the barrier created by the shelter and the short-term protection of its indoor atmosphere.

Scientific studies of Sheltering as a Protective Action

Some early studies of sheltering effectiveness calculated that, for a typical dwelling and a plume lasting 10 minutes, the dose indoors would be about one-tenth of the outside dose. For other types of dwellings and
releases, the indoor dose could be as little as one percent of that received outdoors.2

In this modeled example, a person staying outside would have been exposed to 400 parts per million of the toxic gas for 10 minutes. On the other hand, a person who immediately closed up his house prior to the
arrival of the cloud would have been exposed to no more than 60 parts per million during the same 10 minutes. If the hypothetical toxic gas causes harmful effects in a person exposed to 100 parts per million for
10 minutes, it is clear that sheltering in place would have been beneficial to a person using this technique.

Basically what their saying is that a person is usually safer inside then out. Several examples

Houston, TX on May 11, 1976
A tank truck carrying anhydrous ammonia wrecked on an exit ramp and toppled onto a freeway below. On impact, the tank ruptured and released about 7,500 gallons of ammonia. The ammonia immediately vaporized and formed a thick plume. With winds of about 7 mph, most of the ammonia cloud had dispersed
after 5 minutes. The cloud surrounded the nearby Houston Post newspaper building – birds on the roof were killed. For people within 1,000 feet of the release point, 78 were hospitalized for symptoms of ammonia exposure, 100 were treated for less severe injuries, and 4 died as a result of ammonia exposure. The National
Transportation Safety Board (NTSB) investigation concluded that people who sheltered and stayed inside buildings (including workers in the Houston Post building) received no harm from the ammonia release. NTSB also concluded that people who stayed in their cars generally received less

Pensacola, FL on November 9, 1977
A railroad tank car carrying anhydrous ammonia derailed and was punctured resulting in a release of ammonia vapors. Two deaths and 46 injuries were reported for those who were evacuated. In six
houses that were very close to the accident site, there was no time to evacuate. Those residents closed their windows and doors and stuffed towels under doors and around windows. NTSB concluded that a breathable and survivable atmosphere was maintained

Miamisburg, OH on July 8, 1986
A CSX rail tank car derailed releasing liquid phosphorus. About 30,000 people were evacuated from the surrounding area. However, a local hospital near the accident site was unable to evacuate. The hospital staff and patients sheltered in place and were not injured. (Information from a telephone interview on 12-
15-97 with Lt. Andy Harp, Miamisburg Fire Department, one of the first responders on the scene, as reported by East Harris, TX Manufacturers Association)

And for me the best example of sheltering in place working

Fort Rucker, AL on November 8, 1994
Chlorine gas (150 lbs.) escaped from a sewage treatment facility at the U.S. Army Aviation Center and Fort Rucker. The release occurred in the early evening, 6:10 pm, and lasted for about 2 hours. According to the RMP filed by the facility, 128 people sheltered and 128 people evacuated. This resulted in 21 public
responders being hospitalized , 22 workers being injured and injury to one member of the public who was onsite at the time. The chlorine release also damage plants in the area. Stability conditions of F meant that the cloud of chlorine gas dispersed very slowly; temperature was 65 F and wind at 3 knots from the south.

Some studies have shown that people who are evacuated have a 16% chance is long term illness due to exposure as opposed to only 1% of those that sheltered in place. The chance is immediate injury from exposure during evacuation is 38%.

The best thing for you do to is contact your local or state Emergency Management Agency and find out, how long it would take to set up evacuation, their procedures for evacuation and their thoughts on sheltering in place.

Sheltering in place is not very complicated. All you really need is some plastic and duct tape. I have my day cares putting together kits with Radios, water, snacks, first aid kits and toiletries for less then $75.

More Information if needed
www.redcross.org/preparedness/cdc_english/Sheltering.asp
www.fwps.org/info/emergencies/preparation/shelter.html
www.floodconference.com.au/.../Session%207%20paper%2023%20Coates.pdf
eetd.lbl.gov/ie/pdf/LBNL-62107.pdf