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You know that warm, cozy, sleepy feeling you get after an over-sized meal shared with too many friends and family to fit around a single table? It's some gossip to share in the kitchen, but I will never know the truth of it. My compulsion is to doze off on the couch between two over-stuffed uncles watching the game, where I’m lulled into the safety of sleep by vague murmurs and laughter from the kitchen and the drone of the TV. The post-holiday dinner coma is a comforting part of a familiar holiday tradition. What could possibly be wrong?
Indoor Air Quality
When I do home energy inspections, one of the things I investigate is the air quality inside the home. This involves testing for carbon monoxide (CO), relative humidity (RH), and carbon dioxide (CO2). CO is produced when fuels are not completely burned. A concentration of 0.01 percent CO in air is harmful to humans and 0.3 percent is deadly within minutes. RH is a measure of how much moisture is in the air. RH affects our comfort, but too much moisture in the wrong place can lead to mold growth, which also affects our health. CO2 is a normal result of fuel combustion, and is also a byproduct of our own respiration. CO2 concentration in outdoor air is about 0.04 percent, and the air we exhale contains about 4 percent CO2. These are pretty small numbers, but incredibly important ones if we’d like to stay alive and healthy.
Humans need air that contains at least 20 percent oxygen. Lucky for us, nature has provided us with 21 percent. The main ingredient in air (78 percent) is nitrogen, and the remaining 1 percent is spice in the soup. Mess with the spice, and you ruin the entire meal! The mechanism for removing excess nitrogen from our bodies is through urine, but there is no such efficient biological mechanism for removing most airborne poisons that may be contained in that surprisingly important 1 percent. When CO2 concentration in the air we inhale reaches about 0.12 percent, many of us will start to feel sleepy and maybe head-achy. Not a health risk, but you won’t be functioning at your best. I’ve measured CO2 levels in meeting rooms and school classrooms in excess of .3 percent, eight times higher than normal! Ever wonder why some meetings put you to sleep? Or why your kids are wet noodles when they come home from school? It might not be the presenter’s fault, open a window and let in some fresh air!
The Food Coma
What does all this have to do with your holiday meal? During one family thanksgiving gathering, I got out my CO2 meter to test the air while dinner cooked in the gas oven. The CO2 level in the house quickly shot up to over .15 percent, so we turned on the bathroom exhaust fan. It helped a little, but not much. We needed a large range hood, vented to outside to make a real difference. The CO2 level was closing in on .2 percent and yawns were exchanged by all. Two windows were opened to allow cross ventilation, and within minutes the CO2 levels dropped. But that was just phase one. Cooking complete, windows closed, and fifteen people all exhaling in the dining room meant that CO2 began to rise again. We’ve always blamed the amino acid tryptophan, present in many foods, but I realize now that all those holiday meals at grandma’s house were accompanied by an invisible and unknown poison that put us all to sleep. We were all lethargic from poor indoor air quality, and all we could really manage to do in that environment was watch TV.
A Delicate Mix
The air we breathe is a delicate mix that is easily thrown off balance. Very small changes in its composition can dramatically affect our health, how we think, feel, and behave. Global warming aside, atmospheric CO2 is a pollutant, levels are rising, and our bodies are reacting along with the planet. We are like lobsters that have been thrown into a pot of cold water on the stove top. The heat is on, and we can feel something slowly changing. How long before we start clamoring to get out of the pot?
Get Efficient, Stay Healthy
This year, do your part to keep the flame on the lobster pot low! Check out the Homeowner’s Energy Handbook for ideas. As you tighten up your home for energy efficiency, don’t forget to add a ventilation system for fresh air. Meanwhile, do yourself and your guests a favor by opening a window or two while you’re cooking and entertaining. You’ll be glad you did, and I bet it will lead to more engaging time spent with family and friends.
Paul Scheckel is the author of "The Homeowner's Energy Handbook" and The Home Energy Diet.
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