How to Monitor Indoor Air Quality (IAQ) in Your Smart Home

Because indoor air quality (IAQ) is such an important health issue, I recently wrote about techniques for cleaning the air in a home using the home’s forced air HVAC system. That article can be found here.  However, I only touched on some of the monitors that allow people to measure the air quality in their home.

First it is important for people to understand how important of an issue this is. According to the Environmental Protection Agency (EPA) the air inside a home may be up to five times more polluted than the air outside a home and people may spend up to 90 percent of their time indoors. In our quest to conserve energy, our homes have become so well sealed that it is impacting the quality of air inside them.

In addition, the EPA’s AirNow.gov web site states:

“As people age, their bodies are less able to compensate for the effects of environmental hazards. Air pollution can aggravate heart disease and stroke, lung diseases such as chronic obstructive pulmonary disease and asthma, and diabetes. This leads to increased medication use, more visits to health care providers, admissions to emergency rooms and hospitals, and even death.”

Given the above, it is important to understand the kinds of air quality issues that can exist in a home:

• Particulates are very small particles in the air that can penetrate deep into the lungs. Particulates are divided into two primary categories, PM2.5 and PM10. PM2.5 particles are 2.5 microns, or less, in diameter. Examples of PM2.5 particles are soot and tobacco smoke. On the other hand, PM10 particles are 10 microns, or less, in diameter. Examples are dust, pollen, and mold. Exposure to particulates can cause coughing, sneezing, and irritation of the eyes, nose, and throat. Long term exposure can have negative impacts on people with heart and lung disease.
• Carbon Monoxide (CO) is an odorless, colorless, and poisonous gas. It is generated by incomplete combustion from gas/kerosene fueled space heaters, poorly ventilated furnaces, gas-operated water heaters, wood stoves, fireplaces, gas stoves, car exhaust, and more. Because CO is odorless and colorless it cannot be detected by people that are exposed to it. High levels of CO in a home can cause death.
• Carbon Dioxide (CO2) is a naturally occurring, colorless, and odorless gas that is part of the air we breathe every day. As people breathe, their lungs absorb the oxygen in the air and we exhale CO2.  In a home that is not ventilated properly with fresh air, the occupants, simply through breathing, can use up the oxygen in the air and raise the concentration of CO2. Combustion, for example, from a gas stove or fireplace can also increase the concentration of CO2 in a home. Exposure to even moderate levels of CO2 beyond what is normally found in the air can cause headaches, sleepiness, impaired judgment, nausea, and death in high concentrations.
• Volatile Organic Compounds (VOCs) are emitted from various solids and liquids in a home. Some sources of VOCs are aerosol sprays, stored gasoline, cleaners, disinfectants, new furniture, and building materials. Even cooking can release VOCs into the air. Exposure to VOCs can cause irritation of the eyes, nose, and throat, headaches, and nausea. Some VOCs are known to cause cancer. Sensors typically measure Total VOCs which is abbreviated as TVOC.
• Radon is a colorless, odorless, and radioactive gas that is the result of radium in the soil and rock beneath a home. Radon gas enters a home through small cracks and leaks in the foundation. In homes without a continuous, concrete foundation radon gas can even more easily enter a home through the exposed ground below the house. According to the EPA, “Radon is the second leading cause of lung cancer. Radon is responsible for about 21,000 lung cancer deaths every year.”

With this background it is easy to see how important it is to understand the air quality in a home and, as appropriate, integrate indoor air quality monitors into a smart home so systems can be triggered to address air quality issues.

It should be noted that the foobot evaluated for this article was purchased as part of my previous article “Optimizing Smart Home Air Quality and HVAC Efficiency.”  The Awair and Airthings Wave Plus monitors were both provided by the manufacturers for this article.

Awair

The Awair IAQ monitor includes sensors for PM2.5 particulates, TVOC, CO2, temperature, and humidity. The visually pleasing wood enclosure allows the device to be easily placed anywhere in a home. A built-in light sensor automatically adjusts the intensity of the display so the Awair can be placed in a bedroom without disrupting people’s sleep.  The unique matrix of LEDs provides graphical feedback of the readings from each sensor and an overall pollution score.

Connectivity

The Awair connects to any 2.4GHz Wi-Fi network (5GHz is not supported). Using Wi-Fi connectivity, Awair can be directly integrated with a Nest thermostat to trigger the use of the furnace filter to help clean the air in a home. Alexa and Google Assistant devices can also be integrated with the Awair and used to obtain feedback on the air quality in the home through voice commands.

App

There are both iOS and Android apps available for the Awair. Besides allowing the user to simply view the current IAQ, the app can provide tips for improving IAQ based on the current readings. The app also allows a homeowner to track the IAQ over time so the user can understand how changes they make in their home are helping with their IAQ. Finally, the app can send notifications when the Awair notices changes in the IAQ.

The app makes it easy to setup the Awair:

1. Create an Awair cloud account.
2. Select the option to add an Awair device and the app will automatically connect to the Awair.
3. Choose the home’s Wi-Fi network from the list of available networks and enter the Wi-Fi network’s password.
4. The app also takes you through a short tutorial, which the user can choose to repeat at any time.

Once the setup process is complete the app provides:

• A score screen to view the current sensor readings and an overall air quality score.
• Tips for improving indoor air quality and living within the current conditions in the home. For example, the only “yellow” tagged reading on the Awair I tested was temperature, and I received a tip to warm up the bed at night before climbing in with a hair dryer.
• The “Trends” tab allows the user to graphically view the various sensor readings over time. For convenience, in this view the app supports rotating the phone into portrait mode to make viewing longer trends easier.
• The “Awair+” tab allows the user to easily integrate the Awair with Google Assistant, Amazon Alexa, IFTTT, etc.
• The “Notifications” tab allows the user to view any notifications that have been generated so they won’t be accidentally missed while using the smart phone for other purposes.

Integration

Besides the integrations described above, Awair includes an IFTTT service and a very expansive API.  The IFTTT service includes triggers for when any of the Awair’s sensors collect a reading above a defined threshold for 30 seconds. Actions can, for example, be used to change the display mode of the device.  For example, through IFTTT the Awair can:

• Tell a smart thermostat to circulate air when high CO2 is detected
• Tell a smart thermostat to circulate the air when particulates are high so the HVAC filter will remove them from the air
• Tell a robot vacuum to clean the home when the dust levels are high

The API covers all functionality of the Awair from setting user attributes to reading data from the device.  It is very secure with full OAuth 2.0 authentication required. In addition, the API is exceptionally well documented.

foobot

The foobot IAQ monitor includes sensors for PM2.5 particulates, TVOC, Temperature, and Humidity.  The enclosure is modern and stylish in a white that matches many other IoT devices. IAQ is displayed through color changing LEDs that change from blue to orange depending on whether the IAQ is good or poor. The intensity of the LED can be adjusted in the app allowing the foobot to be placed in a bedroom where a bright LED could disturb the occupants sleep. But, unlike the Awair, the LED intensity doesn’t automatically adjust based on the light level in the room.

Connectivity

The foobot connects to any 2.4GHz Wi-Fi network (5GHz is not supported). Like the Awair, the foobot integrates with a Nest thermostat to automatically clean the air using the HVAC system. In addition, the foobot can directly integrate with an ecobee, Honeywell, or Warmup smart thermostat. Alexa devices can also be integrated with the foobot and used to obtain feedback on the air quality in the home through voice commands. The foobot does not support integration with Google Assistant.

App

There are both iOS and Android apps available for the foobot. The app provides an easy-to-read display of the sensor readings with the ability to quickly know whether any readings are too high. You can also look at graphs of readings of each sensor scaled to minutes, hours, days, or weeks to see trends in your IAQ.

The app makes it easy to walk through the setup of the foobot. After installing the app on a smart phone the user simply:

1. Selects the option “I’ve got a foobot.”
2. Selects the option “Setup your foobot.”
3. The app then informs the user to connect their foobot a maximum of five feet away from their Wi-Fi router/access point.
4. The user is then informed to turn the foobot upside down (the LEDs start to blink fast).
5. The user is then informed to put the foobot back to its normal orientation.
6. The user is then informed to type in the SSID of their Wi-Fi network and the password.
7. Once the foobot connects to the Wi-Fi network it blinks five times signifying that the setup was successful.

The main screen of the app allows you to view the readings from the various sensors, an overall IAQ score, and a calculated value of CO2 in the home. Touching each sensor reading allows you to dive into the reading in more detail including scoring for how the foobot determines if the reading is great, good, fair, or poor. There is also the ability to view tips for improving IAQ. Finally, the app allows the user to graphically view the sensor readings; scaled over time (minutes, hours, days, or weeks).

In addition to providing information on IAQ, the app allows you to view the current outdoor air pollution level with data provided by BreezoMeter.

My one complaint is that the app displays CO2 data readings without the foobot having a CO2 sensor.  The reading is calculated using the other sensors in the foobot and my own experience has been that it isn’t accurate. A rise in TVOC will also cause a rise in the CO2 reading when nothing has changed to actually raise the CO2 level. CO2 is an important indoor air pollutant and the lack of a sensor is a limitation of the foobot when compared to the Awair.

In addition to the app, foobot offers a web dashboard to users. The dashboard allows a user to overlay data from multiple foobots in graphical form, download data in different formats, compare data for different time periods, and more.

API

Besides the integrations described above, foobot includes an IFTTT service and an API. The IFTTT service includes triggers for when any of the foobot’s sensors collect readings above a defined threshold and when a new air quality reading is available. The foobot IFTTT service includes a trigger when someone knocks twice with their hand on the top of the foobot. Some other uses for foobot-IFTTT integration are:

1. Flash the lights when the air quality is poor.
2. Turn on air circulation through a smart thermostat when the air quality is poor.
3. Record air quality readings from the foobot in a Google spreadsheet.

The foobot API is not nearly as extensive as the API provided for the Awair. However, it does allow you to gather the data readings from the device; which is all that is required to integrate the foobot with an automation processor/hub. And, the API is significantly simpler to implement than the Awair because it doesn’t require full OAuth 2.0 security. Some people might view the lower level of security as a negative, but, personally, I don’t feel that someone potentially knowing the IAQ in a home is that much of a violation of personal privacy. OAuth 2.0 is much more appropriate for the Awair whose API includes features for changing all the internal settings that are managed through the app.

To use the foobot API requires an API key that needs to be requested from foobot through their developer portal. With the API, I have written a Crestron module to pull data from a foobot so it can be used to drive actions by a Crestron 3-series automation system. The code can be found on my GitHub.

Airthings Wave Plus

Airthings took a different approach with the Wave Plus. First, the Wave Plus is battery operated. Second, while it does include sensors for temperature, air pressure, humidity, TVOC, and CO2, its primary sensor is for radon.

Radon testing is typically accomplished by purchasing a small sensor from a hardware store, placing it in your home for:

• Two to seven days for a short term test or,
• Ninety days, or more, for a long term test

The sensor is then mailed into a lab where the data is analyzed and a report is mailed to the homeowner.  Radon levels in a home can vary over time due to air pressure, winds, snow cover, rain saturation of the soil, operation of HVAC systems, whether the windows are open/shut, and more.  Because of this, continuous monitoring is an important tool because of the danger that radon gas poses to human health.

The Wave Plus mounts on any wall with a single screw or can simply be placed on a table. Radon gas is heavier than air so the device shouldn’t be mounted on a ceiling; like a smoke detector would. Because the Wave Plus is battery operated, wall mounting the Wave Plus will not leave unsightly wires hanging from the device. In addition, because Bluetooth consumes very little power, the battery expectancy is estimated to be one-and-a-half years.

In normal operation the Wave Plus is innocuous, with no lights that could disturb someone’s sleep if it was mounted in a bedroom. Waving your hand in front of the device will cause a central ring on the device to glow green, yellow, or red for a few seconds; depending on the radon level. My own personal experience is that sometimes it takes a couple of passes waving a hand before the device wakes up.

Connectivity

Unlike the Awair and foobot, the Wave Plus doesn’t connect to the home’s Wi-Fi network. Instead it connects to the homeowner’s smartphone via Bluetooth. One disadvantage of this design is that the device will not automatically update itself as new firmware updates are made available by the manufacturer. The user must perform the updates themselves using the smartphone app.

An optional hub has been announced (but at the time of this article isn’t yet available) that will connect the Wave Plus to the home’s Wi-Fi network. This will allow the homeowner, using the Wave app, to monitor the radon level in the home from anywhere.

Alexa and Google Assistant devices can also be integrated with the Wave Plus and used to obtain readings on the sensors in the device. It should be noted that because the Wave doesn’t connect directly to the home’s Wi-Fi network (without an Airthings bridge) that data only reaches the Airthings cloud service through the Airthings smartphone app. Additionally, if the homeowner is not home or the app is not set for background refresh, then the data on the cloud will become stale and not reflect the actual data readings of the device. A work around for this limitation is to take an old smartphone, load the Airthings app, and leave it plugged in within Bluetooth range of the Airthings Wave Plus.

App

There are both iOS and Android apps available for the Wave Plus. Setup using the app is very simple.

1. First, install the Airthings app on a smart phone, start the app, and press the “Next” button to begin the setup of the device.
2. Next, the app says to pull out the tab in the battery compartment so the battery will make contact with the device; allowing it to receive power.
3. The user then needs to wait for the blue light to start flashing (signifying that the device is in pairing mode) or, if the device was previously powered up, gently knock on the device to enter it into pair mode.
4. Once the user sees the flashing blue light, the user presses the “Start Pairing” button in the app.
5. After pairing is complete, the user can enter the location type for the Wave Plus (Home, Workplace, etc.) and the name of the room the Wave Plus is located in.
6. After a one-hour countdown the Wave Plus displays its initial sensor readings.

It should be noted that internal algorithms work to continually improve the accuracy of the measurements provided by the Airthings Wave Plus. These algorithms run in the background and allow the device to learn about its environment to improve results. According to the manufacturer, the longer the device is left operating the more accurate the sensor readings will be.

The app is pretty basic but easy to use. The home screen displays the readings from the available sensors and a large colored ring that corresponds with the radon level detected with the same color coding as the device itself. Pressing on the ring takes the user to a screen where a graph of the readings from each sensor can be displayed over various timeframes (48 hours, week, month, or year).

Integration

The Wave includes an IFTTT service, but at this time there isn’t a published API. The IFTTT service includes triggers for whenever one of the sensors collects data that is above, or below, a defined threshold. However, the Wave’s IFTTT integration has the same limitation as its integration with Alexa and Google Assistant; it requires data synching through the smart phone app because the Wave doesn’t directly connect to the home’s Wi-Fi network.

Currently there isn’t an API for direct integration with the Wave from third party systems. However, a Google search found a GitHub project where someone reverse engineered Bluetooth communications with the Wave and built that into a Raspberry Pi. The Python code for this can be downloaded off of GitHub.

Summary

*Bluetooth connectivity to the smart app is required for sensor data to be uploaded to the cloud

IoT Security

An important step I take when I connect any IoT device to my network is to use Bitdefender Home Scanner to scan the device for vulnerabilities. Because the Airthings Wave Plus only includes Bluetooth connectivity, this isn’t an issue for this product. Bitdefender didn’t find any vulnerabilities with the Awair monitor. However, Bitdefender identified that the foobot has an http interface and that “http uses an insecure authentication procedure.”

Smart Home Integration

The integration capabilities of an IAQ monitor make it a valuable addition to a smart home. As I pointed out in my previous article, an HVAC system with a smart thermostat and the correct filter can help remove both particulates and VOCs from the air in a home.

Radon and CO2 can only be removed through better venting in the home. This process can be automated with window fans, or a whole house fan, and motorized windows where the fans pull air out of the home and the windows allow fresh, outside, air to enter the home. The logic for this need to include evaluation of the outside temperature so warm, heated air in the winter is not replaced with cold air from the outside.

These are the basic steps to use an IAQ monitor to improve the air quality in a home. However, with creativity, more interesting logic can be developed such as integrating an IAQ monitor with a particulate sensor to trigger vacuuming the floors when particulate levels rise in the home. Another opportunity for integration is to trigger the vent hood above a smart stove if the stove is turned on and the TVOC level in the home rises, as cooking can produce VOC’s.

Conclusion

The devices aren’t perfect and there is no single device that is a must-have because of the different sensors offered by each. The foobot doesn’t offer a CO2 sensor, and neither the foobot, nor the Awair, offer a radon sensor. The Airthings Wave Plus misses out because it doesn’t include Wi-Fi connectivity, a sensor for particulates, and integrations can’t be triggered unless the device is within Bluetooth range of the homeowner’s smartphone so data can make it to the cloud.

All the monitors could offer more value to homeowners by removing their temperature and humidity sensors; which are redundant for anyone with a smart thermostat. The savings could be used to include sensors for more pollutants, as I just outlined above, and CO2.

It should be noted that I found variability in the sensor readings between all these devices. However, without being able to test them in a lab it is hard to comment on which monitors are reporting the correct readings; and which aren’t. As long as the monitor is providing a reasonably close estimate of the air quality in the home it provides the homeowner with information they, or their automation system, can take action on to improve the situation.

Even with the above limitations, an IAQ monitor is a smart addition to any home; smart or not.  The integrations these devices offer add additional value in a smart home where air cleaning, and other tasks, can be automated.