Do you know how to ventilate your home? How often do you open a window or sense the need for fresh air? According to researchers, very few people are aware of the need for ventilation, and many have zero perception of the relationship between indoor air quality and health.
Since the energy crisis in the 1970s our buildings are increasingly airtight, reducing access to fresh air. This has taken a toll on our health, according to Dr. Tim Sharpe of the Glasgow School of Art.
Poor indoor air quality, particularly in bedrooms, is hard for people to detect. There are clear links between poor ventilation and ill-health, so people need to be aware of the buildup of CO2 and other pollutants in their homes and their potential impact on health.
Sharpe and a team of researchers surveyed 200 homeowners and found the following:
- 83% of Mechanical Extract Systems were underperforming, with 42% below Building Regulations requirements for moisture control
- 63% of trickle vents were kept closed
- Only 20% of people leave bedroom windows open at night
- 82% of people had received no advice on ventilation
- There was no perception of Indoor Air Quality (IAQ)
Because of Sharpe’s research, all new buildings in Scotland must now be equipped with CO2 sensors to give residents an indication of how well their homes are being ventilated.
I purchased a CO2 monitor this summer (found here) and watched the levels vary dramatically depending on ventilation. Summer is the time of year when our house is closed up much of the time. Thus our levels, measured in parts per million, were higher than desired. (Optimal levels range from 350 ppm to 1,000 ppm.)
Our levels varied from 1,100 to the mid-300s depending on time of day and access to fresh air. Most of the time they hovered in the 800 range. The CO2 equaled outside air after a monsoon, as seen below.
It’s important to note that while CO2 levels do not give you specifics regarding toxic mold or other contaminants, high CO2 levels do keep bad company and can indicate an unhealthy indoor environment.
How to Ventilate Your Home
- Be more aware of the need for fresh air.
- Take note of the presence of chemicals in the home. Chemicals such as formaldehyde used in building materials will off-gas and impact IAQ. Choose chemical-free household products when possible.
- Watch moisture. Be aware of water leaks. Ideal humidity levels range from 40-50%. (For more on mold growth, see A Beginner’s Guide to Toxic Mold.)
- Keep trickle vents (common in Europe) or windows open when cooking or showering.
- Open windows at night.
- Dry laundry near an open window. (See Dr. Sharpe’s previous study Environmental Assessment of Domestic Laundering.)
- Make sure you understand how the ventilation system of your property works. Clean vents regularly. Here’s a before and after of one of our larger vents.
Dr. Tim Sharpe discusses his research and offers more practical information in this edition of The Connecting Place.
Ventilation is equally important in office settings and schools. Check out these previous posts for more specifics.
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Hello, Andrea! I hadn’t heard of home CO2 monitors before. Very interesting! This is really an important topic because we spend so much of our lives indoors. I live in an area that has long, hot and humid summers and lots of pollen in the spring, so our windows are rarely open from April to October. I know it’s not good, but it’s miserable with the windows open. We do regularly change the filters in the air conditioning system, anyway. Fortunately, we’ll be moving to a much better climate next month. I’m looking forward to having the windows open a lot more there. 🙂
I hope the move goes smoothly for you, Marge. Nice to hear from you!
While I understand the wisdom of keeping windows open at night, nighttime and early AM are when the dew point is highest–and thus, introducing mold into the house would seem to be a problem. Because my health has been severely adversely affected by mold, how would you manage the risk/benefit ratio of open windows vs. introduction of “marker molds”?
That’s an excellent question, Lana. I would be curious about the CO2 levels with the window open vs. window closed. We live in a dry climate so I can’t really compare. If the air is cool and still muggy my guess is it would still be beneficial. I think you have to see how you feel through trial and error.
Andrea, I know my question isn’t relevant to the mold issues discussed above, but I’m wondering if there are health concerns about using ultrasonic pest and insect removers in the home. Would technology like this cause any problems? Thank you.
This is one of those trade-off questions. The benefit of pest control in this manner can outweigh the potential for dirty electricity which I understand can be an issue with these. The use of them is probably better than harsh chemicals.
You’ve given me something to look up – I have never heard of “dirty electricity “. Thanks, Andrea!
Hi, I am working on learning more on the topics you post about, and may need to get your advice as a building biologist. I just got a CO2 meter as well, same brand! Can’t figure out how to contact you directly though.
Raina, You can email me directly at andrea@it-takes-time.com