How to choose an indoor air quality monitor and breathe easy

Indoor air quality monitor

With a little know-how and the right gear, you can breathe easy when it comes to indoor air quality. There are many airborne threats to be aware of, which is where an air quality monitor can come in handy.

The pandemic made us all more aware of issues when it comes to indoor air quality, but ensuring your home has plenty of fresh air isn’t just about fighting off germs. Microscopic pollutants, allergens, dust and a range of noxious gases floating around the room can also take a toll on your health.

Of course, the challenge is measuring all these potential threats to your health and knowing when it’s time to take action. It’s complicated by the fact that “air quality” is such a broad term and there are so many different ways to measure it.

Indoor air quality monitor: common pollutants to consider

Smoke and carbon monoxide

For starters, you should have a few smoke alarms spread around your home, which detect smoke by sensing small particles in the air. They’re sensitive enough to alert you to a fire, but not to pick up on other air quality issues.

The next most common home safety alarm is a carbon monoxide detector, a feature that is also built into some smoke detectors. Carbon monoxide is a colourless and odourless gas that can cause headaches, nausea and vomiting. At high enough levels it’s quickly fatal.

The most common causes of high carbon monoxide levels are incorrectly installed, poorly maintained or poorly ventilated appliances such as stoves and water heaters. Poorly ventilated fireplaces and other gas- or wood-burning appliances can also pose a danger.

Carbon dioxide

Meanwhile, carbon dioxide can also cause asphyxiation at high enough levels, but that’s unlikely to happen in your home. Instead, carbon dioxide is more likely to cause headaches and loss of concentration.

Sensibo Air Pro indoor air quality monitor
You can monitor CO2 levels using the Sensibo Air Pro, which also doubles as a smart AC controller.

We breathe in oxygen and breathe out carbon dioxide, which is why you’d suffocate in a sealed box. Your home isn’t airtight, but poor ventilation which doesn’t offer a steady flow of oxygenated air from outside can see carbon dioxide levels rise.

Other potential sources of carbon dioxide in your home include appliances like dryers, stoves, space heaters and other unvented gas appliances. 

Nitrogen dioxide

Nitrogen dioxide acts mainly as an irritant affecting the mucosa of the eyes, nose, throat and respiratory tract. Low levels can increase the risk of respiratory infections, particularly affecting asthmatics and people with chronic obstructive pulmonary disease. High levels can contribute to the development of acute or chronic bronchitis.

The most common household nitrogen dioxide sources are gas stoves and cooktops. Other sources include unvented or incorrectly installed combustion appliances, tobacco smoke and kerosene heaters.


Radon gas can damage lung tissue and lead to cancer.  It is a radioactive gas that is created by the natural decay of uranium, thorium and radium in soil or water. It typically comes into homes through cracks and holes in the foundations, but it can also be found in some construction materials. 

Particulate matter

Particulate matter refers to tiny particles of solids or liquids floating in the air. Their size is measured in microns. Particles with a diameter of 10 microns or less (PM10) can be inhaled into the lungs. Remember, indoor air quality is also impacted by outdoor air quality and common PM10 sources include smoke, dust, pollen and mould.

Smaller PM2.5 particles can get deeper into the lungs. They tend to come from combustion, such as gas stoves, as well as from food that is burned, seared or braised. Meanwhile, PM1 sources include dust, combustion particles, bacteria and viruses.

Dyson Big + Quiet air quality monitor and purifier
The Dyson Big + Quiet not only monitors quality but it also purifies the air.

Many household air purifiers measure and combat PM2.5 levels, like the Philips Air Performer and the new Dyson Big + Quiet appliance.

Volatile Organic Compounds 

Volatile Organic Compounds (VOCs) like formaldehyde can irritate the eyes, nose and throat, as well as cause difficulty breathing. They’re found in a wide variety of sources including hairspray, cosmetics, cleaning fluids, disinfectants and electronic devices. They also come from paints, solvents, glue, new furniture and carpets, construction materials and plywood. Burning fuels like wood and natural gas also produces VOCs.

Mould and mildew

High temperature and/or humidity can promote the growth of mould and mildew in your home. It can show up as spots, as well as a damp, musty odour. Along with damaging your home, they can also cause nose, throat and respiratory issues.

Choosing an indoor air quality monitor

While every home should have smoke alarms, some of which also detect high carbon monoxide levels, keeping an eye on other potential hazards requires a dedicated indoor air quality monitor.

There are a range of options, each checking different aspects of your home’s air quality. You’ll find a dedicated sensor for every specific health threat, along with combination devices like the Sensibo Air Pro which keeps an eye on a few threats. Some stick on the wall or sit on the shelf, while others are handheld and portable.

Choosing the right sensor for your home starts with considering the biggest potential air quality concerns in your specific dwelling – especially if anyone in your household has a medical condition impacted by air quality.

There are multiple ways to monitor external air quality factors that also impact indoor air quality. Many state-based environmental agencies have information available online, while Google recently added air quality readings directly within the Maps app.

Some options are just alarms that trigger at dangerous levels, like smoke and carbon monoxide alarms designed to alert the entire household to an immediate threat. You can pair these with smart devices like the Apple HomePod that notify you whenever an alarm triggers. Others are sensors that track levels of different threats over time, so you can see the results of your efforts to improve the air quality in your home.

Apple HomePod
Smart speakers like the Apple HomePod can even send you alerts when a smoke alarm goes off at home.

While sensors typically don’t have built-in alarms, some feature a built-in display so you can easily check current conditions. They might also support smartphone alerts to warn you when something reaches critical levels, along with smart home integration and the ability to connect with Alexa, Siri or Google Assistant.

Keep in mind that indoor air quality sensors are starting to introduce subscription services for accessing some of their advanced features. It’s important to read the fine print to see if the feature you’re after requires a subscription and decide if you’re prepared to hand over your money every month for that peace of mind.

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