Breathe Better. Live Smarter.®

The Terrestream Indoor Air Quality Sensor

One device. Six sensors. Twelve signals. Indoor readings connected to outdoor context and plain-English recommendations. Terrestream fuses your home's air with live weather, pollen, and smoke data, so every suggestion fits your real conditions.

$249 USD Fast shipping via FedEx

Order yours See the connected experience

  • $249 USD, one-time
  • No subscription required
  • Free apps, web dashboard and account
  • 1-year limited warranty
  • 30-day returns
  • Privacy-first air data

Six sensors. Twelve signals.

A smart indoor air quality sensor for the rooms you care about most.

Terrestream measures CO2, PM1.0, PM2.5, PM4.0, PM10, VOC Index, NOx Index, temperature, humidity, pressure, and light, calculates an IAQ index from the particle readings, then connects those indoor readings to outdoor context and plain-English recommendations.

Terrestream is an IAQ monitor, not a smoke alarm, carbon-monoxide alarm, combustible-gas alarm, radon monitor, medical device, or certification by itself.

Bedroom air-quality monitoring scenario

Best for

Bedrooms, kitchens, wildfire-smoke days, dust questions, and households that want explanations instead of isolated numbers.

Terrestream homeowner dashboard preview with example data, a kitchen ventilation recommendation, outdoor context, and room-by-room trends
Product preview · Example data

Integrated with

Compatible with Alexa. Home Assistant and MQTT for local workflows. Alexa setup →

On this page

Scenarios

Six Everyday Examples

Illustrative scenarios with example readings, not measured case studies. Room size, ventilation, activity, and sensor placement change the readings you may see. Explore how the display responds as conditions change.

A chef tossing peanuts in a wok over a gas burner, steam and aromatics rising

Smoke from the wok

Wok over the gas burner. Peanuts tossing, chilies smoking in oil. Window closed (January). Within five minutes the device sees what your nose half-registers: VOC index climbing through Yellow into Orange, PM2.5 trailing. By minute twenty, chilies blooming, the underglow touches a brief Maroon. Screen reads VOC 489.

A child asleep in a softly lit bedroom, a teddy bear beside the pillow

Stale air at 3am

Door shut. One sleeper, lights off. At lights-out the device reads CO2 450 ppm (Green). By midnight, 880. By 3am, 1,250, with the underglow crossed into Orange. By morning it's reached 1,580 and the ring is Red.

A laptop, coffee, and headphones on a desk by a window at sunset

Stuffy by 3pm

Home office. Door closed, sun tracking across the desk. At 9am the device reads CO2 450, temp 21°C (Green). By noon, 900 and 23° (Yellow). By 3pm, 1,250 and 25°, and the underglow has shifted to Orange. By 5pm: CO2 1,460, temp 25.8°. IAQ tracks particles, so it stays Green at 33.

A honeybee gathering pollen from a cluster of small purple flowers

When pollen drifts in

A bright day in May, windows cracked. At 7am the device reads PM10 35 µg/m³ (Green). By 11am, 140 (Yellow). By 2pm, 240 (Orange). By 5pm the underglow has shifted to Purple: PM10 380 µg/m³, PM2.5 55 µg/m³. Pollen drifting in on the breeze.

A couple carrying a new gray sofa into a sunlit living room

That new-couch smell

Couch delivery, late afternoon. Before it's in the door the device reads VOC index 28 (Green). Within an hour: 280 (Orange). By morning, the foam and fabric still off-gassing, it's reached 475 (Purple). The ring sits in the deep end for two days while the new-couch smell fades.

A bright living room with full-height patio doors wide open to a green garden

A morning like most

Patio doors open to the garden. The device reads CO2 430 ppm, PM2.5 5 µg/m³, VOC index 30, humidity 47%, temp 22°. The ring sits Green and the screen reads its calm baseline.

The app is quiet. No notes, no flags. Most days, your home reads like this. The device speaks up when something shifts. The rest of the time, it just keeps watching.

Signals

Twelve Signals, One Language

Right now Good everything reads close to baseline.

Try a scenario:

A child blowing out birthday candles, exhaling CO2

CO2 Carbon Dioxide

The gas you exhale. Climbs in closed rooms; outdoors it sits near 420 ppm.

— ppm
—
A sunlit beach scene, warm temperature

°F Temperature

How warm the room is. Comfort sits around 68–72 °F.

— °F
—
A still lake at sunset, calm air

IAQ Air Quality

Calculated from particles, not measured: the worse of the PM2.5 and PM10 scores on the U.S. EPA AQI scale (0–500).

—
—
Lit candles releasing volatile organic compounds

VOC Volatile Compounds

Invisible smelly stuff: cooking, cleaning, paint, candles, new furniture.

— index
—
A blue gas stove flame, emitting nitrogen oxides

NOx Nitrogen Oxides

Combustion's signature. Gas stoves, candles, and traffic creeping in from outside.

— index
—
A vivid microscopic render of submicron airborne particles in purple, blue, and pink

PM1.0 Submicron Particles

The smallest particles the sensor reports, a subset of PM2.5. Shown for completeness; there is no air-quality standard for this fraction yet.

— µg/m³
—
A close-up of cigarette smoke, fine particulate matter

PM2.5 Fine Particles

Smoke-fine particles. Small enough to slip past your nose deep into the lungs.

— µg/m³
—
Crushed rainbow-coloured powder arranged in a spectrum, evoking fine respirable dust

PM4.0 Respirable Particles

The respirable coarse fraction, between PM2.5 and PM10. Reported for completeness; no dedicated standard exists for it.

— µg/m³
—
A field of pollen-laden grasses, coarse particulates

PM10 Coarse Particles

Larger particles: pollen, dust, building debris. Mostly trapped in the airways.

— µg/m³
—
Storm clouds gathering, barometric pressure shift

hPa Barometric Pressure

The weight of the atmosphere above you. Drops often signal a storm coming.

— hPa
—
A hand wiping condensation and water droplets from a cold window at sunrise

RH Relative Humidity

How much moisture is in the air. Comfort and low mold risk sit between 30 and 50 percent.

— %
—
A bright, sunlit kitchen with white tulips on the counter

lux Ambient Light

How bright the room is. Used for the screen night-dimming and circadian context, not air quality.

— lux
—
  1. Good
  2. Moderate
  3. Unhealthy for
    Sensitive Groups
  4. Unhealthy
  5. Very
    Unhealthy
  6. Hazardous

Same six bands across every signal.

Band labels reflect Terrestream's interpretation of US EPA AQI category thresholds applied to indoor measurements. They are not an EPA-regulated indoor air-quality rating. Terrestream is a monitoring tool, not a medical device, and does not diagnose, treat, or prevent any health condition. See Terms §6.5.

Full technical specifications

The System

From the room to your dashboard

The device, web dashboard and apps help you follow your air and decide what to do next.

Terrestream device screen showing Carbon Dioxide at 440 ppm, Good status, plus temperature, IAQ, VOC, and NOₓ tiles

The device

Always on. Glance-and-go. Twelve signals, one color language. The screen is your at-a-glance answer; the underglow is the across-the-room answer.

Terrestream homeowner dashboard preview with example data, a kitchen ventilation recommendation, outdoor context, and room-by-room trends

The web app

The long view. Hours, days, weeks of trend data, so you can spot what you wouldn't notice on the device itself: the rooms that drift, the times of day that keep crossing a warning level, the events that cluster. Your Year in Air record lives here too.

Terrestream app Today preview with example data recommending 11 minutes of ventilation and showing Indoor Air Index 15

The phone app

What the device noticed while you were out. Quiet notifications with a practical next step. Set up the device and see your home from anywhere.

Terrestream on Apple Watch: Living room, Air is good, CO₂ 440 ppm

Apple Watch

Room status, readings and ventilation guidance, a glance away. A companion to the iPhone app.

Optional Apple Watch companion requires a compatible Apple Watch and paired iPhone, sold separately. Explore the Watch app

Tour the connected experience

Use Cases

Where Terrestream Fits

A single home or a manufacturing floor — the same twelve signals, the same sensor inside, the same calibration data published by the manufacturer.

Top-down floor plan with four green sensor-placement markers

Drag to rotate · click a dot to highlight that room's tile below.

Kitchen monitoring room

Kitchen

See cooking particles and gas-index changes as they happen, so you know when to run the hood or air out the room.

Living room monitoring room

Living room

Track the air everyone shares, from cooking drift and rising CO2 to particles coming through open doors and windows.

Main bedroom monitoring room

Main bedroom

See how CO2 builds overnight and whether ventilation keeps pace. Terrestream shows the pattern; it does not diagnose a health condition.

Kids' bedroom monitoring room

Kids' bedroom

Watch overnight CO2, particles, and pollen in a smaller sleeping space, then compare indoor changes with outdoor conditions.

Home office monitoring room

Home office

Catch CO2 buildup and particle spikes during the workday, with a clear cue when fresh air or filtration may help.

Home gym monitoring room

Home gym

See CO2 and humidity rise during a workout, so you can ventilate before the room feels stale or damp.

Garage & workshop monitoring room

Garage & workshop

Track VOC, NOx Index, and particle changes from solvents, sanding, and vehicle exhaust. Terrestream does not measure regulatory NO2 or carbon monoxide; keep a dedicated CO alarm.

Basement monitoring room

Basement

See slow humidity and VOC changes from damp conditions, stored paint, fuel, and cleaners.

Intelligence

Indoor Meets Outdoor

Dozens of live data streams feed specific analyses that turn into things you can actually do to change your indoor environment. Take control of your indoor space.

Weather, air quality, pollen, and smoke data come from Open-Meteo, Google, NOAA, and NASA.

Illustrative view of a person opening a window when outdoor air is clear.

Open when outside air helps

Clear outdoor conditions can support a ventilation recommendation.

Illustrative view of the same window kept closed when outdoor smoke is present.

Hold when outside air hurts

Outdoor smoke context can change the recommendation even when the room needs attention.

  1. Terrestream device showing room readings

    01 · Measure

    Start with the room

    Read CO2, particles, gas indexes, and comfort conditions on the device. Each channel answers a different question.

  2. Example homeowner dashboard with room readings and outdoor context

    02 · Compare

    Check the context

    Compare indoor changes with outdoor conditions and room history. This dashboard preview uses example data; matching patterns suggest possibilities, not proof of a source.

  3. Terrestream mobile app showing readings and recommendations

    03 · Follow up

    See what changed afterward

    Review a suggestion alongside its readings, then check the trend after you act. The sensor can show whether a measured condition changed; it cannot prove why.

Architecture

Inside the Device

Two custom-tooled circuit boards do the work behind everything you just saw. Here's what's on them. Drag to rotate.
Dual-core CPU Powerful processor runs the device and reads the sensors.
Wi-Fi & Bluetooth Wi-Fi (2.4 GHz) connects the app, dashboard and recommendations; Bluetooth pairs with your phone.
Pressure & temperature Adds pressure context for weather, infiltration, and floor changes. It does not directly detect an open window.
Light sensor Display auto-dims at night, brightens by day.
Audio amplifier Real stereo-grade audio - not random tones and beeps.
USB-C (18W) Premium 6 ft (1.8 m) cable and 18W supply included.
Off-board connections Sockets for the air-quality sensor, display, LED ring, and speaker.

Drag to rotate · labels track the components as you turn the board

Custom 15-LED ring printed circuit board with LEDs arranged around the device's perimeter

The 15-LED underglow ring

A second custom PCB, uncommon in this category as of May 2026, with fifteen individually addressable RGB LEDs arranged around the device's perimeter to cast the colored underglow you see from across the room: the "answer at a glance" your eyes catch before you read the screen.

Driven directly by the main board's SK6812-protocol controller, the ring inherits the firmware's full six-band color language. Green for fresh, deepening through Yellow, Orange, Red, Purple, and Maroon as readings shift. No off-the-shelf module here; this one was designed and tooled in-house specifically for the device.

  1. Good
  2. Moderate
  3. Unhealthy for
    Sensitive Groups
  4. Unhealthy
  5. Very
    Unhealthy
  6. Hazardous
Illustrative rear view of the Terrestream sensing hardware.
The rear sensing path and named component stack.
Illustrative Terrestream display and color status view.
The touchscreen and room-readable status language.
Illustrative Terrestream Quiet Hours status view.
Quiet Hours keep the status useful with a calmer presentation.

Comparison

How It Compares

How to choose

A useful IAQ monitor should answer more than one number.

When buyers compare indoor air monitors, the real questions are whether CO2 is measured directly, which PM size bins are reported, whether gas readings are indexes or compound-specific lab values, how outdoor context is handled, and whether the system turns patterns into actions.

  • CO2Look for real CO2 measurement, not only an estimated air-quality score.
  • ParticlesPM2.5 matters, but PM1.0, PM4.0, and PM10 add useful source context.
  • GasesVOC Index and NOx Index are trend and event signals, not lab TVOC or regulatory NO2.
  • ContextOutdoor air, weather, pollen, smoke, pressure, and room history turn a spike into a plausible cause.
Detailed guides All monitors AirGradient Ruuvi Air Awair Airthings Aranet4
Detailed comparison
Terrestream AirGradient ONE Ruuvi Air Awair Element Airthings View Plus Apollo AIR-1 Aranet4 HOME
CO2 ✓ Sensirion SEN66 ✓ Senseair S8/S88 ✓ Sensirion SEN66 ✓ not publicly disclosed ✓ NDIR ✓ Sensirion SCD40 (optional) ✓ NDIR
Particulate matter PM1.0 · PM2.5 · PM4.0 · PM10 PM1.0 · PM2.5 · PM10 PM1.0 · PM2.5 · PM4.0 · PM10 PM2.5 PM2.5 PM1.0 · PM2.5 · PM4.0 · PM10 ✗
VOC and NOx VOC: ✓ Sensirion algorithm
NOx: ✓ Sensirion algorithm		 VOC: ✓ Sensirion algorithm
NOx: ✓ Sensirion algorithm		 VOC: ✓ Sensirion algorithm
NOx: ✓ Sensirion algorithm		 VOC: ✓ not publicly disclosed
NOx: ✗		 VOC: ✓ not publicly disclosed
NOx: ✗		 VOC: ✓ Sensirion algorithm
NOx: ✓ Sensirion algorithm		 VOC: ✗
NOx: ✗
Display 3.5″ color LCD, touchscreen small OLED light indicator only LED display with on-device readings E-ink, small ✗ E-ink
Underglow color ring 15-LED custom board 11 RGB LEDs color-coded light indicator ✗ ✗ RGB pixels; no 15-LED ring ✗
Indoor + outdoor data fusion weather, AQI, pollen blended ✗ ✗ ✗ outdoor pollen context ✗ ✗
Mobile app ✓ included web dashboard ✓ Ruuvi Station ✓ Free app (no documented paid tier) ✓ via Home Assistant ✓
Home Assistant ✓ Native ✓ Built-in HA integration (local polling) ✓ Built-in HA Bluetooth (local push) ✓ HA integration (local API preferred) ✓ HA integration (cloud polling) ✓ Native (ESPHome) ✓ Built-in HA Bluetooth (local push)
MQTT ✓ Native ✓ (stock firmware) via optional Ruuvi Gateway not documented for the consumer device Airthings for Business only Custom ESPHome YAML (not native) not documented for the HOME model
Apple Home / Google Home / Alexa Compatible with Alexa1 via HA Matter bridge via HA bridge Google + Alexa + IFTTT (no HomeKit) Google + Alexa + IFTTT + Homey (no HomeKit) via HA Matter bridge via HA bridge
Matter via HA bridge1 via HA bridge via HA bridge ✗ ✗ via HA bridge via HA bridge
Subscription required None No local lock-in; 12 mo hosted dashboard/API included Free app; Gateway/Cloud for remote monitoring Free app; cloud-history terms not verified None; trends + history in the free app None None
Price (MSRP) $249 USD $230 USD assembled / $138 USD kit 149€ excluding tax $299 USD $329.99 USD $109.99 USD base $189 USD

1 Alexa compatibility: The Terrestream skill supports US English in the United States and requires internet, cloud sync and a linked Terrestream account. No Terrestream subscription is required. The sensor is not a native Matter device. Alexa setup guide.

Current manufacturer product pages and Home Assistant documentation were checked on 2026-09-12. Prices exclude shipping and tax where applicable and can vary by region or promotion. Competitor information is subject to change. AirGradient, Ruuvi, Awair, Airthings, Apollo, and Aranet are trademarks of their respective owners; no affiliation or endorsement implied. Terrestream and Ruuvi Air both use Sensirion's SEN66 multi-gas platform; the comparison focuses on the surrounding product, connectivity, dashboard, and interpretation system. If you spot an inaccuracy, let us know and we'll correct it.

Current primary sources: AirGradient ONE · Ruuvi Air · Awair Element · Airthings View Plus · Apollo AIR-1 · Aranet4 HOME. Home Assistant behavior: AirGradient · Ruuvi · Awair · Airthings · Aranet.

Review the Terrestream measurement evidence for the SEN66, BMP390L, and OPT3001 evidence behind the device architecture.

Included

What's included

Everything the device does on your own network is free, forever. The apps, web dashboard and account are free, and core recommendations are included.

Free

On the device & your local network — always free

  • All twelve signals, on-device screen & 15-LED underglow
  • Local HTTP API, Home Assistant & MQTT
  • Mobile app + web dashboard on every device · up to 90 days of readings (charts show the last 30 days)

With a free account

Through Terrestream's cloud

  • Core recommendations included
  • App notifications and history
  • Needs 2.4 GHz Wi-Fi and internet

FAQ

Common Questions

Quick answers. The full support hub at terrestream.com/support covers the rest.

Does Terrestream work with Apple Watch?

Yes. Check room readings and ventilation guidance on a compatible Apple Watch paired with an iPhone. The companion does not work on non-Apple watches. Your Terrestream sensor measures the air; the Watch displays its readings. Apple Watch and iPhone are sold separately.

How long does setup take?

About a minute. Plug in via USB-C, pair to Wi-Fi through the on-device touchscreen or the mobile app, and the first reading appears within 60 seconds. The screen walks you through it.

Do I need a subscription?

No. The apps, web dashboard and account are free, and core recommendations are included.

Will it work without Wi-Fi?

Yes. Plug it in and the device measures and shows readings on its own screen, with no Wi-Fi or account. Connected features need 2.4 GHz Wi-Fi, internet and a free account: history, recommendations, outdoor context (weather, AQI, pollen), and push notifications. The sensors keep reading whether or not the cloud is reachable.

How accurate is it?

Per the published Sensirion SEN66 specification: CO2 at ±(50 ppm + 2.5% of reading) in the 400–1,000 ppm range, after 2 days of operation that include fresh air and with fresh air at least once a week; Sensirion VOC and NOx indices per their published algorithms; and Sensirion-calibrated PM (calibrated against TSI DustTrak™ DRX 8533). Bosch BMP390L delivers ±0.5 hPa pressure accuracy. Full details in Specifications.

Will the sensors degrade over time?

Sensirion publishes a continuous-IAQ mission profile of more than ten years for the SEN66, with measurable drift typically appearing after about five years of continuous use. CO2, VOC, and NOx baselines auto-calibrate during normal operation; PM is laser-based and factory-calibrated. For ongoing accuracy verification, recalibration, or replacement past the warranty period, see Terms §6.

What's the warranty?

1-year limited device warranty from Aerodyne against defects in materials or workmanship. Accuracy follows Sensirion's published datasheet under the conditions it states; for CO2, that means after 2 days of operation that include fresh air, with fresh air at least once a week. Gradual sensor drift over time is normal and is not a defect.

Is Terrestream compatible with Alexa?

Yes. Compatible with Alexa through the Terrestream skill. Link your account to ask for supported readings and create routines. Requires internet, cloud sync and a verified Terrestream account that owns the sensor. Available in the United States with Alexa set to English (US). No Terrestream subscription required. See the Alexa setup guide. Open the Terrestream skill.

Does it integrate with my smart home?

Use the Terrestream Alexa skill for supported readings and routines in US English. For local workflows, use the Terrestream Local Home Assistant integration or publish to your own MQTT broker. Alexa does not require Home Assistant or Matterbridge. The sensor is not a native Matter device.

What indoor air quality sensor should I buy?

Choose a monitor that directly measures the problems you care about, explains likely sources, and fits your home workflow. Terrestream is strongest when you want CO2, multiple PM size bins, VOC and NOx event context, outdoor air context, Home Assistant or MQTT support, and plain-English recommendations.

Does Terrestream detect wildfire smoke and dust?

Terrestream measures PM1.0, PM2.5, PM4.0, and PM10, then compares indoor particle changes with outdoor smoke, weather, pollen, and room history. It is an IAQ monitor, not an emergency smoke alarm.

Does Terrestream measure radon?

No. Terrestream does not measure radon. If radon is your primary concern, use a dedicated radon monitor or professional radon test alongside Terrestream.

Breathe Better. Live Smarter.

Bring Terrestream into your home.

One device. Six sensors. Twelve signals. Indoor readings connected to outdoor context and plain-English recommendations. Start with one room, then expand wherever air quality matters most.

$249 USD one-time

Order yours
Setup Datasheet Compliance
  • No subscription required
  • 30-day returns
  • 1-year limited warranty
  • Fast shipping via FedEx

Six sensors. Twelve signals.

Built on genuine Sensirion, Bosch, and Texas Instruments sensors.

  • CO₂
  • IAQ
  • VOC
  • NOₓ
  • PM1.0
  • PM2.5
  • PM4.0
  • PM10
  • Temperature
  • Humidity
  • Pressure
  • Light

Included

  • In the box: the sensor, a 6 ft (1.8 m) USB-C cable, a power adapter and a printed guide
  • Free apps, web dashboard and account
  • Privacy-first air data

Compatible with Home Assistant via MQTT

WhatsApp support