5 ways your Home Assistant server can use an air quality monitor

Since adding an air quality monitor to my Home Assistant server, I’ve been intrigued by the data I’ve collected. I’m now able to create automations around these numbers, triggering alerts and devices when certain criteria are met.

Here are some ideas that might convince you it’s time to invest in an air quality monitor (or several).

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Receive an alert when PM 2.5 reaches a certain level

I’m lucky to live in a city with relatively clean air, close to the coast and covered in trees. As a result, air quality is generally excellent, with PM 2.5 levels barely recorded. Unfortunately, we also face bushfires in the warmer months and controlled burning (designed to prevent bushfires) in the colder, drier months.

As a result, air quality can drop whenever there is smoke in the sky, and this isn’t always immediately noticeable until the whole house smells good. Sometimes PM 2.5 levels reach 30 to 50 inside before realizing something is wrong and running around the house closing the windows. Since my usual levels are 3 or lower, I have now set an alert on Home Assistant to send me a notification whenever PM 2.5 levels reach 10.

This gives me enough notice to walk outside, take a deep breath, and decide if I need to seal the house to protect myself from the smoke. No house is truly airtight, but sealing doors and windows can make a huge difference. One way to improve this automation would be to install an air quality monitor outside, under the porch, sheltered from the rain but still exposed to outside air, for early warning.

Track the Humidity (and Do Something)

High humidity exacerbates high temperatures and makes cold temperatures even worse. At the same time, low humidity can be a bane for many people, leading to dry skin and other problems. For most people, an intermediate level is best.

Many air quality sensors detect much more than particles and other pollutants, and having access to humidity readings is both interesting and useful. If you integrate your cooling or heating system with Home Assistant, you can trigger it to dry out your home if excessive humidity is detected. You can do the same with humidifiers and dehumidifiers to remove or add humidity to rooms.

Monitoring humidity levels could even save you money on your heating bill.

Receive an alert when your home needs ventilation

The most surprising thing I learned when I added an air quality monitor to my home is that volatile organic compounds tend to linger long after the event that caused them. For example, boiling water with my gas stove significantly increases VOC levels throughout the house, even if I burn gas in the kitchen.

These levels are significantly reduced if I do it with an open window in the same room, while the VOCs disappear quickly when I open more windows in my home. Just learning this taught me a lot about home ventilation, but you can take it a step further and receive an alert on your mobile device (or smart speaker, or any other device).

VOCs aren’t the only trigger you can use here, since CO2 levels and even PM 2.5 (caused by cooking smoke) can also indicate that ventilation is needed.

Trigger fans, windows and other devices

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You can use just about any data point from an air quality monitor in Home Assistant as a trigger for an automation, which means you can automate all sorts of behaviors that you would normally need to perform manually.

For example, excessive humidity in a bathroom may indicate that someone is taking a shower. Excessive humidity in the kitchen suggests that you are cooking. The threshold humidity levels for these areas may be different, but by adding a simple on-off relay to your extractor fan in either room, you can tell Home Assistant to vent excessive humidity for you via simple automation.

This means you don’t need to go back to the bathroom after a shower to turn off the fan since it will automatically turn off when the humidity level has dropped enough. You can perform similar tasks in other rooms, such as automatically ventilating the space housing your 3D printer.

It might even give you the push you need to install motorized windows in your home, especially in hard-to-reach places like the ceiling.

Build conditional automations based on different readings

Credit: Justin Duino / How-To Geek

Home Assistant’s ability to take conditions into account in its automations is one of the reasons it’s so powerful. This works especially well when you bring together multiple data sources, such as an air quality sensor located indoors and another located outside. This allows you to create smarter automations.

For example, you could have an automation that sends you a notification to open the window when a certain level of VOCs is detected. This is fine, as long as it’s not colder or too hot outside. By adding an “If” consideration, you can tell the automation to do something else, like turn on the central air if it’s below or above a certain outdoor temperature.

The same goes for other factors, like PM 2.5. There’s no point opening windows to ventilate your home if the PM 2.5 levels outside are through the roof. An alert that, if a certain part of the house falls below a certain temperature compared to your living room or kitchen, could be used to trigger an alert that a window has been left open in the dead of winter.

Beyond these many useful automation possibilities, air quality sensors provide you with interesting data about your home. The one I use from IKEA is now affordable, so it might be a good buy if you’re looking for something nice and cheap that works via Zigbee.