7 Tips for Good Indoor Air Quality in Winter – GWC Mag

Here we are early in another winter. Because of the weather, most of us spend more time indoors. And the people with whom we share those indoor spaces are getting colds, flu, and other winter maladies. So, what you can do to improve your indoor air quality (IAQ) during these cold, dark months of breathing a lot of indoor air? Well, I’ve got a few tips. Below are 7 good IAQ practices that can help you breathe a little easier as you wait for the return of nicer weather in the spring and summer.

1. Use the range hood

The holidays may be over, but many people are doing more cooking at home now since restaurant meals have become so expensive. And, as you may know, cooking is responsible for a lot of the indoor air pollutants in homes. I certainly see it in my IAQ monitors. There’s an easy-to-identify cooking spike in the graph of volatile organic chemical (VOC) measurements most evenings in my home. And that’s with the range hood turned on.

The biggest reason, though, that range hoods don’t help indoor air quality more than they do is…drum roll, please…they don’t get turned on. Yep. The number one problem with range hoods is that the cook doesn’t flip that switch. So while you’re cooking—especially if you cook with gas and even more especially if you bake with gas—hit that switch, please. Your body will thank you.

2. Turn on bath fans

Using the range hood helps not only to remove pollutants at the source, though. It also brings in outdoor air (through random leaks in the building enclosure, but that’s another issue) to dilute the pollutants that don’t get pulled up into the range hood. So you can run the range hood even when you’re not cooking to help with pollutant levels. And then turn on bathroom exhaust fans to increase the ventilation and help with other parts of the home.

Yeah, you’re not going to dilute indoor air pollutants if the air you bring in is worse than the air in the house, so check the outdoor air quality first. Just go online and search for something like “air quality near me.” Or just look at the weather app on your smartphone.

Exhaust-only ventilation isn’t great in humid climates in warm weather, so this advice works for most people in winter. If you’re in Miami and it’s 86 °F (30 °C) with a 70 °F (21 °C) dew point, you’ll want to moderate the amount of exhaust ventilation you do. But still use the range hood when you cook!

3. Set the thermostat fan to “on” (maybe!)

Speaking of humid climates, setting the thermostat fan to “on” is generally a bad idea in warm, humid weather. You can end up with high indoor humidity and mold problems. But the nice thing about winter (for those of us in the Northern Hemisphere anyway) is that the weather is cooler and drier.

So you can set the thermostat to “fan on” instead of “auto” without worrying so much about problems with high humidity. Doing so can help your IAQ by providing more filtration of the air. One thing I didn’t include as a separate tip in this list is having a clean filter. So before you change that fan setting, you might want to change the filter.

Caution: Even though you’re not likely to add moisture to the home by doing this in winter, it’s possible that other problems could make this tactic a bad idea. If you have significant duct leakage, you could make the indoor air too dry. You also may be more likely to put carbon monoxide into your home. This strategy is mainly for heating systems with good duct systems and good filtration.

4. Use standalone filtration

If you’re still worried about not getting enough filtration with the heating system fan running continuously, set up some standalone filtration systems. There are plenty of those available commercially. And if you’re reading this blog, you probably already know about the Corsi-Rosenthal box, a DIY box fan air cleaner with high-efficiency filters and a high clean air delivery rate. These devices are very good at removing the tiny invisible particles floating around in your indoor air.

5. Monitor carbon monoxide

I would be remiss not to mention carbon monoxide (CO) here. It’s a colorless odorless gas that can kill you at high levels. The standard CO detectors won’t alarm until the level is high enough to put you in the hospital. But you could have lower CO levels for days or months that can give you headaches, dizziness, weakness, rapid heartbeat, shortness of breath, chest pain, or disorientation.

The best thing you can do is to get a low-level carbon monoxide monitor. The standard CO detectors will allow you to breathe levels of carbon monoxide that you really don’t want replacing oxygen in your blood.

6. Monitor carbon dioxide

Carbon dioxide (CO2) is a different thing altogether. It’s not poisonous the way carbon monoxide is, at least not at the levels you’ll ever experience at home. It’s an indicator of how much dilution you’re getting for the indoor air. Most of the carbon dioxide in your home’s air is (or should be) the result of people breathing.

The air that comes out of your lungs has about 40,000 parts per million (ppm) of CO2 in it. That quickly gets diluted with the room air, but if there’s not enough air exchange with outdoor air, the indoor CO2 level rises. That indicates that other pollutants may be building up in your indoor air as well. The level most people take as threshold for indoor CO2 is 1,000 ppm. When it goes higher than that, do more of numbers 1 and 2 above. If that still doesn’t help, consider the last tip below.

7. Open windows

If the weather outdoors isn’t too bad, you can crack a window or two to get more air exchange and dilution of pollutants. Yes, you may have to run the heating system more and thus use more energy, but health is more important than energy use. Besides, if you have a bunch of people over, they’re helping you heat the house, too. Each person gives off about the same amount of heat as a 60 watt incandescent light bulb.

There you have it. A little roundup of things you can do to improve your indoor air quality during the winter. For more good info on IAQ, see the articles below, the EPA’s indoor air quality pages, and ROCIS (Reducing Outdoor Contaminants in Indoor Spaces). Also, check out the new podcast called Indoor Air Pod. I just did an interview with them last month, and it’ll be out sometime this month.

Here’s to safe, healthy, and happy winter!

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Allison A. Bailes III, PhD is a speaker, writer, building science consultant, and the founder of Energy Vanguard in Decatur, Georgia. He has a doctorate in physics and is the author of a bestselling book on building science. He also writes the Energy Vanguard Blog. For more updates, you can subscribe to Energy Vanguard’s weekly newsletter and follow him on LinkedIn.