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16 guides.
A home monitor is a bundle of small sensors, each good at one thing. Knowing which sensor sits behind each number tells you which readings to trust and which to treat as a trend.
The View Plus is the most complete home air monitor Airthings makes: radon plus particles, CO2 and VOCs, on batteries or USB-C. It is expensive, and worth it mainly if you want radon too.
The Atmotube PRO 2 clips to a bag and measures particles, CO2, VOCs and NOx wherever you go. Its predecessor tested well for particles in South Coast AQMD's program; the PRO 2 adds CO2.
The Awair Element looks better than most monitors and measures the five things most people care about. It is sold through Awair rather than Amazon, and independent accuracy data is thin.
The Awair Omni is built for offices and buildings, with a dashboard for fleets of monitors and RESET accreditation. In a home, you pay for features you will not use.
On a smoke day, the number that matters is smoke CADR. These certified purifiers deliver the most of it for the money, and the EPA's own research shows what a box fan and four filters can do in a pinch.
Some home monitors track a reference instrument closely; others barely at all. Here are South Coast AQMD's independent PM2.5 results by model, and what makers' accuracy claims really cover.
EPA's AQI is built for outdoor air and 24-hour averages. The AQI or score on a home monitor is a maker's translation of a live reading. Here is how to read both.
The AirVisual Pro's strength is context: it shows your indoor PM2.5 and CO2 next to outdoor air from IQAir's network. Independent field results were more modest than cheaper rivals, and it is pricey.
MERV is a 1 to 16 score for how well a filter catches particles of 0.3 to 10 microns. EPA suggests MERV 13 or the highest your system can handle; here is what each level actually catches.
PM10 is every inhalable particle up to 10 micrometers; PM2.5 is the fine fraction inside it. The fine fraction is the bigger health concern, but the coarse part is the dust and pollen you can see.
PM2.5 is the particle size EPA says poses the greatest risk to health. Here are the official limits, what your monitor's number means, and what actually brings it down indoors.
The PurpleAir Flex is built to hang outside and feed the public PurpleAir map. It is a good outdoor particle sensor with independent test results. For indoor monitoring, PurpleAir points to other models.
The Qingping Air Monitor Lite is cheap, reads particles and CO2, works with Apple Home, and did well in South Coast AQMD's independent field test. It has no VOC or radon sensor and needs to stay plugged in.
The M10+ is Temtop's current M10: a cheap, battery-friendly e-ink monitor for CO2, particles and VOCs. It is a sensible bedroom or desk monitor; just do not expect lab-grade numbers.
A monitor is only as good as its sensors. We picked the ones with laser particle sensors, true NDIR CO2 and, where it exists, independent accuracy testing from South Coast AQMD.
