Posts Tagged ‘haz-mat’

Evacuation vs Remaining Indoors

Emergency preparedness routinely includes plans for getting out – family meeting spots, school fire drills, and tsunami evacuation routes, to name a few. There are literally thousands of hits on Google for “bug-out bag” – portable 72 hour survival kits for use in emergency evacuation (my favorite evacuation kit nickname is GOOD bag – Get Out Of Dodge!). But sometimes your best bet is to stay put! Just ask 140,000 Japanese living near the Fukushima Nuclear Power Plant – those living between 12 and 18 miles from the plant were  initially told to stay inside.

Why would you ever want to stay in a dangerous area? Well, sometimes your exposure to a hazard is greater outside than inside, at least for a few hours. If there is a crazy in the neighborhood running around with a gun or bomb, you are better off in than out. Similarly, in severe winter storms, most people just hunker down. These are so obvious, we don’t even consider them as “sheltering in place” – it’s just common sense.

Airborne Chemical, Biological, or Radiation Exposures

Tsunami damage at Fukushima Diiachi - cause of severe nuclear accident. Photo by Martyn Williams.

Tsunami damage at Fukushima Diiachi – cause of severe nuclear accident. Photo by Martyn Williams.

Staying indoors can be equally important if a there is a chemical, biological, or radiologic threat in your area.  In studies, they found an average house changes less than 1/3 of its air in an hour – newer homes exchange even less. In a room sealed with duct tape and plastic, chemical levels after one hour are less than 1/10 of the amount outside. In other words, if you go outside, you get hit with the full dose of the toxic substance. In a sealed room, you get less than a tenth of the exposure, even an hour later. Some types of radiation are also blocked reasonably well by stone or brick walls.

If the event is not controlled, eventually the contaminant enters the building air supply or is even absorbed by the building itself, but this takes hours. For many exposures, the amount in the outside air has dropped off significantly by then, and it is safe to come out. Even when the exposure is still present, emergency teams hopefully have identified the agent within 2-3 hours, figured out wind directions and at-risk areas, and determined a response plan, including orderly evacuation if needed.

Shelter In Place Diagram - http://www.ready.gov/shelter

Shelter In Place Diagram – http://www.ready.gov/shelter

Preparations for Sheltering in Place

Advance preparation for sheltering in place is an essential part of basic emergency planning – at home, work, and school. Identify the room with the fewest doors and windows – interior is best. Above the ground level is better for most exposures (except for radiation exposures, where a basement is better), but the level of the room is not as important as fewer windows and the ability for everyone to get inside quickly. 10 square feet of floor space per person provides enough air for up to 5 hours (hopefully you’ll be out long before that). If possible, the room should have access to water and a hard-wired phone. Store a radio and batteries, duct tape, scissors, and plastic sheeting in the room. To be really ready, precut and label your plastic to quickly cover all doors, windows, vents, electrical outlets, and switches in the room – the faster you can enter and seal a room in an emergency, the less the exposure. Know how to turn off heating, ventilating and air conditioning systems for the building.

The words “shelter in place” are a public safety term. If you hear them, take immediate shelter wherever you are – home, work, school, or inside the nearest building. Alerts may be announced on TV or radio, over loudspeakers from emergency vehicles, or even as an alert on your cell phone. Instructions tell you whether to simply stay indoors, or whether to minimize air exchange with the outside. If you do not or cannot receive instructions, make your best decision based on available information. If you smell, taste, see, or feel contaminants in the air, stay inside a sealed room. In general, whenever there is no immediate threat from an emergency, chemical or not, it is best to stay put and gather more information. Even if evacuation is eventually needed, planned evacuations run a lot better than emergency evacuations (remember those Katrina pictures of traffic jams extending for miles?).

Steps To Take If Told to Shelter In Place

When sheltering in place, no one leaves the building (including pets). Lock outside doors and windows. If there is a risk of explosion, close window shades, blinds or curtains. Turn off fans, heating, ventilation, and air conditioning systems. Bring your disaster supplies to your shelter room, and turn on your emergency radio. If instructed to seal the room, use duct tape and plastic sheeting to seal all cracks around the doors. Tape plastic over windows and vents, and seal electrical outlets and other openings. If you don’t have duct tape and plastic, use anything you can find to block air from easily flowing into the room (packing tape, rugs, plastic bags, newspaper or clothing). Call your emergency contacts to let them know where you are, but otherwise save phone lines for emergencies. Keep the radio on until told either to evacuate or given the all-clear. When you leave the room, open all windows and doors, turn on heating, ventilating and air conditioning systems, and go outside until the building air exchanges with the now hopefully clean outdoor air.

Risk of Chemical Exposure Is Greater Than I Expected

Bhopal Union Carbide Memorial. Over 16,000 people are thought to have died from effects of the 1984 gas leak. Photo by Luca Frediani, uploaded by Simone.lippi

Bhopal Union Carbide Memorial. Over 16,000 people died from effects of the 1984 gas leak. Photo by Luca Frediani, uploaded by Simone.lippi

Despite my work in emergency preparedness, my paranoia about terrorist incidents is actually quite low, so I was not originally convinced about the necessity for shelter-in-place plans. Since then, Hazardous Materials (Haz-Mat) reports have enlightened me about the frequency of trains that derail, trucks that crash, and chemical plants with fires or accidents. The statistics are amazingly difficult to find on-line, although one site mentioned 21 chemical accidents a day in the United States alone. Another official site stated there are too many incidents to actually analyze statistics, and many go events unreported. It is very difficult to find information about the types of chemicals used, stored, or transported in your area. I guarantee there are a lot more than you might expect, particularly if you have a major highway or rail line near you. 

I now highly recommend adding shelter in place to your emergency plans. At least then you’ll have a choice about “should you stay or should you go”. For more information, The National Terror Alert Response Center (a private homeland security blog, despite the name), has a good Shelter In Place page, with step by step instructions on what to do. The FEMA Ready web site has Shelter in Place FAQs, many of which you might not think to ask on your own. So go invest in some duct tape and plastic sheeting. It really works!

Stay safe,

Sheila Sund, M.D.

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