How to improve and track your home’s air quality

If the pandemic was the big story of 2020, then climate change was the big story of 2021, with prolonged freezes in Texas, raging wildfires in California, and devastating floods in Europe. Yet even as more and more people wake up to the reality of a hotter world, we’re apparently still not ready to pull out all the stops to prevent another half-degree rise in temperature. We are, however, increasingly looking for policies — and devices — that can mitigate the impact of climate change on an individual level.

As we’ve written, one of the biggest impacts of climate change is on air quality. I’ve spent the past few years playing with a variety of options designed to ensure clean air, from standalone air quality monitors for inside and outside the home, as well as air purifiers. It’s a big area for investment. Even Amazon is releasing a smart air quality monitor, which will ship in early December.

So what factors should people take into consideration when trying to assess the quality of their indoor air, and how should they attempt to clean it if problems arise?

First, let’s talk about measurement. When it comes to indoor air quality monitors, there are dozens of options out there. Generally speaking, they will track some subset of the following five things: temperature, humidity, non-volatile organic compounds (VOCs), particulates, and carbon dioxide. Some might also track carbon monoxide and radon.

These devices may also use their sensor data to create algorithms that will tell you the likelihood of mold growth or illness caused by poor ventilation. Some will track carbon dioxide, and will tell you when the air quality is no longer conducive to productivity (CO2 can make you sleepy). The caveat, however, is that everyone’s algorithms are different, and while there is research about CO2 making people sleepy, those personalized CO2 trackers feel pretty gimmicky.

When looking for a tracker, it’s worth noting what, exactly, it tracks. For example, I love my Awair Glow monitor, which tracks temperature, humidity, CO2, and VOCs, but after using it for a few years I realized that, other than opening a window, nothing I do will change the VOC reading. And even when I do open the window, that reading eventually shoots back up after closing it.

It’s also worth knowing what today’s filters are best at filtering. To address those persistently low VOC readings I would need an air purifier that uses an activated carbon filter to clean the air, but it looks like the most effective way to use it would be on a home HVAC system that vents air outside. There are a few air purifiers that use active carbon filtration, but I’ve not tested any except the Molekule, which was a total waste of money. It looked nice, though.

When it comes to climate change, the biggest culprit to bad indoor air is smoke from wildfires. Both this year and last year, we ran our air purifiers constantly, for days at a time, in an attempt to reduce the particulate matter in our house caused by wildfire smoke. I ran four different purifiers this year alone: an older Coway, a “smart” Coway, and two versions of the Filtrete Smart Air Purifier that uses the statically charged Filtrete filters.

As a result, I have the following suggestions. First up, if you or someone you live with has allergies and/or you live in a place prone to wildfires, you should have an air purifier. And that air purifier should have a HEPA filter and be sized appropriately for the room you want to clean.

If you don’t live in an area with wildfires and are only dealing with allergies, I’d recommend running an air purifier (again sized for the room) for an hour before going to bed, max. For that use case, you don’t need either an air quality monitor or a smart air purifier; all you really need are good HEPA filters. You don’t need monitoring because allergens may not show up on the monitors. Concentration isn’t the main problem here; rather, it’s simply the presence of the allergen.

But if you also live in a wildfire-prone area or are super concerned with your indoor air quality because you cook a lot or use a wood-burning fireplace, get an air purifier with an internal monitoring feature. If you’re feeling super nerdy, go ahead and spring for a filter with an app, although I don’t think it’s necessary. Smart purifiers have integrated monitors that track particulates and sometimes temperature or humidity as well.

For me, the best experience comes from setting these machines on automatic and letting them adjust to the filtration needs of the air around them. When in automatic mode, they quietly exchange air in the background, and when they sense particulates, they boost their air exchange to filter air more quickly.

In the case of the 3M’s Filtrete line, if you’ve downloaded the app you can set it to notify you to turn the purifier on whenever it senses bad air. We use that feature with our largest purifier in the family room because generally the air in there is pretty good; we don’t tend to run it in there unless the outdoor air quality is terrible or we are cooking. This saves us energy and a bit on the filter life. (Most machines run at an energy level that will add about $1 to $3 a month to your utility bill, depending on what your utility charges per kilowatt-hour.)

The 3M app also tells me the outside air quality and temperature (although it runs about 2 degrees off from other thermometers in the room). It lets me see trends, although I found I don’t care to see them. In fact, without the ability to tie my temperature and humidity sensors into other apps, such as my HVAC, the external monitors are pretty useless.

The one exception to that is the Airthings Wave monitor that I put in a storage closet where the humidity is high and the temperature is cold. I worry about the likelihood of mold developing, so I keep the monitor there because Airthings has a mold assessment algorithm that I think might warn me if temps get too out of line. I used to have a Bluetooth version of the monitor but upgraded to a Wi-Fi gateway because Wi-Fi allows me to get notifications from anywhere as opposed to me actively walking by the area to check it every few days.

Finally, if you’re going to buy a monitor, I recommend setting it up for notifications around specific parameters, especially those parameters you can change. If you can open a window to lower VOCs or carbon dioxide levels, then get a notification for when those are high and take action. But for the most bang for your buck, it’s much nicer to have a monitor that’s integrated with a device that can take action on your behalf. Because it’s only through such integration that smart home devices actually become smart.