7 Good IAQ Practices for the Holidays
Here we are in the midst of another holiday season. You may already find yourself in a house full of relatives and friends, wondering what you might be able to do at the last minute to improve your indoor air quality (IAQ) during the festivities. Well, I’ve got a few tips for you today. Here are 7 good IAQ practices that can help you breathe a little easier over the holidays.
1. Use the range hood!
Holidays mean more cooking than usual. And cooking is responsible for a lot of the indoor air pollutants in homes. I see it in my IAQ monitors. There’s an easy to identify cooking spike in the graph of volatile organic chemical (VOC) measurements. 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. 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!)
And speaking of humid climates, setting the thermostat fan to “on” is a bad idea in warm, humid weather. You can end up with high indoor humidity and mold problems. But the nice thing about these holidays (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 about humidity problems. 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, go 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 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 but sleep on low levels either. 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. I know it’s a bit late for this holiday season, so you’re going to have to rely on the ventilation strategies mentioned in the other parts of this article for now.
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 over the holidays. 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 this week, and it’ll be out sometime next month.
Here’s to safe, healthy, and happy holidays!
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.
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4 Ways a Bad Duct System Can Lead to Poor Indoor Air Quality
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As part of our remodel that added a new full basement under our house I included an HRV. We live in the Pacific NW so this is supposed to be the right choice vs ERV. At present it is connected only to basement rooms and has stubs up into the rest of our two story Victorian for inclusion as we rework those floors. Already we love it. The basement now generally smells like nothing. It is fully finished and had that new home smell. We use it as our base of operations and paint things down there and when we do, I set it to MAX for the first hour or so after application of stinkier paints and the smell is undetectable in the rest of the house so it seems to be working really well. The ductwork was a real pain as I ran almost all of it between and through the floor joists, the latter using 3″ x 7″ oval but so worth it. We did include a bath fan in the new bath down there and will in the baths we plan to add upstairs. Many Victorians had no baths so we are catching the building up after 125 years.
Indoor humidity is also affected in locations like San Diego where the outdoor air can be extremely dry. If you run the kitchen exhaust hood for a very long during a Santa Ana events here in San Diego, you’ll find the indoor humidity levels can drop extremely low in spite of any effort to humidify the house, which I do during the these events. It’s also important to note that if you are using an ultrasonic humidifier in your house your need to make sure that the water has zero parts per million of dissolved solids. I found that the orange flame on my stove burners were being caused by using water from my RO system that had only 20 ppm of dissolved solids and that the humidifier was then pumping tiny particles back into the air that caused the stove burners to burn orange. My solution was to use a secondary “zero filtering” system that removed the rest of the dissolved solids from the humidifier water (DI water is recommended by the manufacturers). Since I was starting with only 20 ppm my zero filters lasts a very long time only having to remove a small amount of dissolved solids. Prior to discovering this anomaly with ultrasonic humidifiers, I thought there was some issue with my stove. Now the nice blue stove flame is back. Running a natural gas stove is yet another issue of course as we’ve all found out with recent reports and running the kitchen exhaust hood can help mitigate some of the resulting pollutants until you can convert to electric, which most cooks like my wife hate, so that might not happen for us, lol.
Just be very careful with those humidifiers. Even in the high desert mountains where humidity is often in the teens, many homes that try to humidify end up with mold in hidden places. And SD is already a pretty moldy place. I recently checked out over a dozen short-term rentals and long-stay hotels, and every one had mold.
Introduce her to 21st century induction electric cooking – boils water faster than gas.
I always use ceiling fans when I humidify to mix the air to avoid local wet spots. And it can get so dry that you get shocked all the time during santa anna events. But I’m 8-10 miles from the beach and much drier than the beach which is generally always high humidity, 70+%. I agree San Diego beaches and the zone close to the beach probably has major mold issues but SD has a large variety of micro-climates that don’t fit the definition of humid at all. It is important to mix the air if you humidify though and keep it in a health range.
Happy New Year!
I understand what you are trying to promote with #3 but I am wary of giving the advice to run the AHU all the time for good IAQ. More than once, that advice has led to degraded IAQ due to poor humidity control (yes, less of a risk in colder months) but mainly the concern is due to leaky ductwork and associated pressure imbalance.
Leaky ducts can greatly contribute to pollutants being exchanged with the indoor occupants and can effectively over-dry a home during colder months (due to duct leakage spurred infiltration) – the opposite is true in humid months. Recommendations to run the fan continuously for IAQ without specifying that the ducts are proven to be air tight could backfire.
Cheers, -mikeb