Six Handheld Particle Counters for HVAC Filter Testing
A comparison of six handheld particle counters suitable for HVAC filter testing, covering channel count, sampling flow, data logging, and calibration claims.
Read Guide→CO₂ & Air Quality
CO₂ monitors, PM2.5, VOCs, indoor air quality and more.
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Buying Guides
Best Radon Test Kits: 6 Options From Lab Kits to Digital Monitors
Two mail-in lab kits listed under EPA measurement programmes, and four digital monitors that charge no lab fee, compared on what each one is actually for.
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Best Air Quality Monitors for Basements: 6 Picks for Radon, Damp and Combustion
Six monitors for the three problems a basement actually has: radon seeping from the ground, humidity that never leaves, and combustion appliances in an enclosed space.
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Best Outdoor Air Quality Monitors: 6 Picks for Measuring the Air at Your Own Address
Six monitors that measure outdoor particulates, from weatherproof mounted stations with professional laser sensors to handheld analysers you carry outside.
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Best CO2 Monitors for Greenhouses: 7 Picks for Enrichment and Ventilation
Seven carbon dioxide instruments sorted by what each listing states: NDIR monitors for watching a grow space, and a controller that switches enrichment and exhaust equipment for you.
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Qingping Air Monitor Lite vs Qingping CO2 Monitor: Five Metrics or a Better CO2 Story?
The Lite states PM2.5, PM10, CO2, temperature and humidity with HomeKit support. The CO2 Monitor states a Swiss Sensirion NDIR sensor, wider stated ranges and remote monitoring through Qingping IoT.
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GoveeLife H5106 vs IQAir AirVisual: Indoor Number or Indoor and Outdoor Together?
The H5106 reports indoor PM2.5 with a stated accuracy of 15 micrograms per cubic metre. The IQAir bundle adds a weatherproof outdoor monitor with two laser sensors and up to eight parameters.
Read Guide→Airthings View Plus vs GoveeLife H5106: Full Picture or Particulates Only?
The View Plus states radon, PM2.5, CO2, VOC, humidity, temperature and pressure on WiFi. The H5106 states PM2.5, temperature and humidity with a published accuracy figure for each.
Read Guide→GoveeLife H5106 vs Temtop S1: Two Small PM2.5 Monitors Compared
Both measure PM2.5 with temperature and humidity. The H5106 states PM2.5 accuracy of 15 micrograms per cubic metre and a two second refresh; the S1 states a laser particle sensor and an AQI display.
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Airthings Wave Plus vs Wave Enhance: Radon or Noise and Light?
Both state CO2, VOC, humidity, temperature and pressure over Bluetooth. The Wave Plus adds radon; the Wave Enhance drops radon and adds noise and light sensors.
Read Guide→Airthings View Plus vs Corentium Home 2: Everything, or Radon Done Simply?
The View Plus adds PM2.5, CO2, VOC and pressure to radon on WiFi. The Corentium Home 2 is a Bluetooth radon monitor with temperature and humidity and nothing else.
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SwitchBot CO2 Detector vs GoveeLife H5140: Two Stated Accuracy Figures Compared
The SwitchBot states a Swiss NDIR sensor with 50 ppm accuracy across 400 to 9,000 ppm updating every second. The GoveeLife states an SCD4x photoacoustic NDIR sensor at 40 ppm plus 5 percent with pressure compensation.
Read Guide→Product Reviews
Sacnahe Air Quality Monitor Review: Seven Readings, No Sensor Named, No Accuracy Given
A WiFi monitor claiming AQI, CO2, PM2.5, PM1.0, PM10, TVOC and HCHO with Tuya app logging, reviewed from a listing that never says how any of it is measured.
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POWERTEC AD1001 Review: An NDIR Monitor Aimed at the Workshop, With Ranges but No Accuracy
A seven inch multi sensor monitor with an NDIR CO2 sensor, electrochemical formaldehyde, semiconductor TVOC and laser particle sensing, reviewed from the listing.
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Extech IAQ320 Review: CO2 and PM2.5 With Indicators You Can Read Across the Room
An indoor air quality meter and datalogger stating simultaneous PM2.5, CO2, temperature, humidity and a health index, with a large LED display and two tri-colour side bars for PM2.5 and CO2.
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Extech CO250 Review: A 0 to 5000 PPM NDIR Meter With a Datalogger
A handheld carbon dioxide meter stating an NDIR sensor measuring 0 to 5,000 ppm, with simultaneous temperature, humidity, dew point and wet bulb, a datalogger and a backlit LCD.
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Temtop P600 Review: PM2.5 and PM10 With a 12 Hour Histogram
A handheld particulate monitor stating a second generation laser sensor with a 20,000 hour lifespan, PM2.5 and PM10 readings with colour health indicators and 12 hours of stored data shown as a histogram.
Read Review→GoveeLife H5106 Review: PM2.5 With Published Accuracy and a Two Second Refresh
A wired PM2.5, temperature and humidity monitor stating accuracy of 15 micrograms per cubic metre, 0.54 F and 3 percent relative humidity, with a two second correction interval and a four level LED indicator.
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GoveeLife H5140 Review: An SCD4x CO2 Monitor With Altitude Compensation
A carbon dioxide monitor stating an SCD4x photoacoustic NDIR sensor with accuracy of 40 ppm plus 5 percent, a 5 second refresh, built-in pressure compensation and buzzer, app and email alerts.
Read Review→SwitchBot Meter Pro Review: Temperature, Humidity and Matter Integration
A large-screen temperature and humidity monitor with a clock, comfort indicator and hub-based smart-home integration; the Amazon listing is the CO₂ model.
Read Review→SwitchBot Meter Pro CO₂ Monitor Review: Smart-Home CO₂ Tracking
A large-screen CO₂, temperature and humidity monitor with a Swiss-made NDIR sensor, ±50 ppm stated accuracy, one-second readings and up to 12 months of battery.
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PurpleAir PIXEL Review: How Useful Is This Ultra-Compact PM Monitor?
PurpleAir's smallest indoor particle sensor: a single laser counter, USB-C power, a colour light and Wi-Fi to the PurpleAir app; not listed on Amazon US.
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PurpleAir Touch Review: Indoor Air Quality at a Glance
PurpleAir's indoor particle sensor with a touch-controlled colour light, USB-C power and Wi-Fi reporting to the PurpleAir map; not listed on Amazon US.
Read Review→PurpleAir Classic Plus Review: Research-Oriented Outdoor PM Monitoring
The PurpleAir Classic with on-board SD card logging: two laser particle counters, Wi-Fi and local storage for research use; not listed on Amazon US.
Read Review→Learning Center
Short-Term vs Long-Term Radon Readings Explained
The 24-hour number tells you what is happening now. The 90-day number tells you your risk.
Read Article→What Is Radon and Why Is Long-Term Monitoring Important?
A radioactive gas from the ground, the second leading cause of lung cancer, and invisible to every sense.
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What Is Formaldehyde and How Do Consumer Monitors Detect It?
The one VOC with its own guideline, its own sensor and a habit of coming from your furniture.
Read Article→Why VOC Readings Rise After Painting or Cleaning
Solvents evaporate for hours; some coatings off-gas for weeks. The monitor shows the whole curve.
Read Article→VOC vs TVOC: What Is Actually Being Reported?
VOC is a family of chemicals. TVOC is a sensor's guess at their sum. Neither is a specific measurement.
Read Article→What Is TVOC on an Air Quality Monitor?
Total volatile organic compounds: one number for hundreds of chemicals, from one sensor that cannot tell them apart.
Read Article→Why Do Particle Sensors Disagree With Each Other?
They count light, not mass, and each converts with its own assumptions.
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Can a Humidifier Affect Particle Monitor Readings?
Ultrasonic humidifiers turn dissolved minerals into fine dust. Evaporative ones do not.
Read Article→Why Does PM2.5 Spike While Cooking?
Hot oil, searing and toasting generate fine aerosol. Cooking is the biggest particle source in most homes.
Read Article→What Is PM1 and How Is It Different From PM2.5?
PM1 is the sub-micrometer fraction: combustion soot and the particles that reach the bloodstream.
Read Article→Why Indoor Air Quality Can Be Worse Than Outdoor Air
Small volume, many sources, slow exchange. The math of a building explains the numbers.
Read Article→Why Air Quality Changes After Cleaning a Room
Sprays spike VOCs, dusting spikes particles, and the monitor sees both before you smell them.
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