Best for
Bedrooms, kitchens, wildfire-smoke days, dust questions, and households that want explanations instead of isolated numbers.
Breathe Better. Live Smarter.®
The Terrestream Indoor Air Quality Sensor
One sensor. 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
- Dashboard and mobile app included
- 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, IAQ, PM1.0, PM2.5, PM4.0, PM10, VOC Index, NOx Index, temperature, humidity, pressure, and light, 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.
Integrated with
Home Assistant and MQTT. Works with the Home Assistant Matter bridge for Apple, Google, Alexa, and SmartThings compatibility.
Scenarios
Six Real Situations
Six ordinary moments in a week, each shifting the device's colors. The same color language across every measurement: green is good, red is loud, the device only speaks when the air does.
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.
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.
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°. By 3pm: 1,250 and 25° (Yellow). By 5pm the underglow has shifted to Orange: CO2 1,460, temp 25.8°, IAQ composite 122.
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.
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 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:
CO2 Carbon Dioxide
The gas you exhale. Climbs in closed rooms; outdoors it sits near 420 ppm.
—
ppm
—
°F Temperature
How warm the room is. Comfort sits around 68–72 °F.
—
°F
—
IAQ Air Quality
The headline score that summarizes everything else: particulates, gases, comfort.
—
—
VOC Volatile Compounds
Invisible smelly stuff: cooking, cleaning, paint, candles, new furniture.
—
index
—
NOx Nitrogen Oxides
Combustion's signature. Gas stoves, candles, and traffic creeping in from outside.
—
index
—
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
—
PM2.5 Fine Particles
Smoke-fine particles. Small enough to slip past your nose deep into the lungs.
—
µg/m³
—
PM4.0 Respirable Particles
The respirable coarse fraction, between PM2.5 and PM10. Reported for completeness; no dedicated standard exists for it.
—
µg/m³
—
PM10 Coarse Particles
Larger particles: pollen, dust, building debris. Mostly trapped in the airways.
—
µg/m³
—
hPa Barometric Pressure
The weight of the atmosphere above you. Drops often signal a storm coming.
—
hPa
—
RH Relative Humidity
How much moisture is in the air. Comfort and low mold risk sit between 30 and 50 percent.
—
%
—
lux Ambient Light
How bright the room is. Used for the screen night-dimming and circadian context, not air quality.
—
lux
—
- Good
- Moderate
- Unhealthy for
Sensitive Groups - Unhealthy
- Very
Unhealthy - 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 §19.
The System
More Than Just a Sensor
You're not just buying hardware. The device is one piece. The web app, mobile app, and local integrations turn it into a connected system that watches, remembers, and quietly nudges you when something shifts.
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.
The web app
The long view. Hours, days, weeks of trend data. AI insights surface patterns you wouldn't notice on the device itself: the rooms that drift, the times of day that linger orange, the events that cluster.
The phone app
What the device noticed while you were out. Quiet, suggestive notifications, never commands. Set up the device, see your home from anywhere, and read the year-in-air letter each January.
Local control
It joins the smart-home stack you already run.
Home Assistant, MQTT, and local HTTP API access are built into the device. Matter, Apple Home, Google Home, Alexa, and SmartThings are bridged through Home Assistant.
See Intelligence integrationsSetup
A real first-run path, not a loose PDF.
Power it, join the setup network or pair from the app, connect 2.4 GHz Wi-Fi, claim the device, then place it where room air can move.
Preview setupEvidence
The datasheet is part of the buying path.
The product datasheet and component datasheets are published, linked, and versioned so serious buyers can inspect the sensor stack before checkout.
Explore the sensor source libraryUse 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.
Drag to rotate · scroll to zoom · click a dot to highlight that room's tile below.
On the plan
Kitchen
Where most of your home's air-quality events happen. Gas-stove NOx, cooking PM2.5, VOCs from oils and cleaning. The first place a sensor pays for itself.
Living room
Where the household actually breathes. Catches drift from cooking, occupant CO2, and anything blowing in from open windows or doors.
Main bedroom
CO2 climbs overnight behind a closed door. ASHRAE 62.1 calls for ventilation when occupied-space CO2 drifts above ~1,000 ppm; a high morning reading tells you when to crack a window.
Kids' bedroom
Smaller rooms saturate CO2 faster overnight. Pollen and PM concentrations are worth tracking in any sleeping space. Knowing when ventilation drops below ASHRAE 62.1 guidance is the actionable signal.
Beyond the plan
Home office
Long-day CO2 drift and the afternoon focus slump tied to ventilation. PM from printers and paper handling. The room that quietly costs you productivity.
Home gym
Heavy breathing saturates CO2 fast in a small room. Sweat lifts humidity into mold-friendly territory. Knowing when to crack a window mid-session is the win.
Garage & workshop
Vehicle exhaust can push combustion gases and PM2.5 through the shared wall. Solvents, finishes, and sanding push VOC + PM. Terrestream reports VOC and NOx Index trends, not regulatory NO2; carbon monoxide needs a dedicated CO alarm.
Basement
Underground humidity drives mold; stored paint, fuel, and cleaning supplies off-gas VOCs slowly. The kind of slow buildup you only notice once it's already a problem.
Office
Continuous IAQ monitoring for productivity, employee well-being, and the standards your facilities team already cares about.
Covers ASHRAE 62.1 parameters
ASHRAE 62.1 (Ventilation for Acceptable Indoor Air Quality) calls out CO2, particulates, VOCs, temperature, and humidity. We measure all of them, continuously.
Reads at WELL Building Standard thresholds
WELL v2's IAQ feature sets specific absolute limits: PM2.5 below 12 μg/m³, CO2 staged at 600 / 750 / 900 ppm depending on space type. The SEN66 senses across all those ranges with published accuracy.
Plugs into your BMS
Native Home Assistant integration + MQTT publishing means existing dashboards see Terrestream data without per-platform code.
Terrestream datasheet (PDF) · Sensirion SEN66 datasheet (PDF) · the published accuracy and parameter specs behind every claim above.
Terrestream is not WELL- or LEED-certified. The above describes the sensor's measurement capabilities aligned with these standards' parameter lists and threshold ranges.
Classroom
What every facilities director knows but few classrooms measure: CO2 above 1,000 ppm correlates with measurable drops in cognitive function.
EPA Tools for Schools priorities
The EPA's Indoor Air Quality Tools for Schools program identifies CO2, particulates, and VOCs as the priority indicators. We measure all three, with the same sensor in every room.
CO2-cognition research grounded
Studies from Harvard COGfx and LBNL link CO2 above ~1,000 ppm to measurable drops in cognitive function. Real-time CO2 flags when ventilation lapses, before students lose focus.
Per-room visibility
Which classrooms drift after lunch. Which east-facing rooms heat up by 1pm. Which need door cracks. Administrators see the whole school in one view.
Terrestream datasheet (PDF) · Sensirion SEN66 datasheet (PDF) · the published accuracy and parameter specs behind every claim above.
Terrestream holds no specific educational-facility accreditation. The parameters measured align with the priority indicators identified by US EPA IAQ guidance for schools.
Industrial
Speaks the language of OSHA and occupational hygiene at a fraction of the cost of a calibrated reference instrument.
Continuous trend context
CO2, PM size bins, VOC Index, and NOx Index are logged continuously for process-control alerts and follow-up. Regulatory OSHA determinations still require the appropriate reference instruments and professional workflow.
Factory-calibrated against a reference instrument
Sensirion calibrates PM measurement against the TSI DustTrak™ DRX 8533, a reference-class gravimetric instrument used in occupational-hygiene studies. The calibration data ships with each SEN66.
Continuous logging built in
Cloud and on-device storage of every reading. Time-stamped, exportable, defensible for ACGIH TLV trend monitoring and process-control alerts.
Terrestream datasheet (PDF) · Sensirion SEN66 datasheet (PDF) · the published accuracy and parameter specs behind every claim above.
Terrestream is not a substitute for OSHA reference instruments where regulatory compliance requires them. It is a continuous indicator suitable for trend monitoring and process-control alerts.
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.
Outdoor context comes from named sources: Open-Meteo, Google Air Quality (US EPA AQI), Google Pollen, and NOAA HMS / NASA FIRMS smoke. See how we source it →
-
Live
Streams flow in
The device's twelve signals join with weather, AQI, pollen, wind, and astronomical signals from open public data.
-
Smart
Models find the signal
Eight focused analyses learn your home's rhythms: when CO2 climbs, when smoke is upwind, when cooking is happening.
-
Useful
Insights come out
Quiet, specific suggestions you can act on. Alerts when something genuinely shifts. The once-a-year letter in January.
Indoor (your device)
Outdoor (open data)
Analysis
Output
Insights
What an Insight Actually Reads Like
Four real examples from the dashboard and mobile app. Specific, situational, written in language a person can act on, not air-quality jargon.
-
Ventilation advisor · just now
"You opened the kitchen window at 9:42 pm and CO2 dropped from 1,250 to 580 ppm by 10:30 pm. Worth doing again. That's the fastest you've ventilated all month."
-
Outdoor attribution · 6 minutes ago
"Today's PM2.5 spike isn't your kitchen. Wildfire smoke from upwind, expected to clear by 8 pm. Keep windows closed until at least 6."
-
Pattern recognition · 3 nights running
"The kids' bedroom CO2 has been creeping above 1,400 ppm three nights running. A cracked door usually fixes this. Try it tonight?"
-
Storm-front predictor · in ~4 hours
"Storm front coming. Pressure dropping 12 hPa over the next four hours. Worth knowing if you're prone to barometric headaches."
Insights are AI-generated suggestions and informational estimates, not medical, regulatory, or safety advice. See Terms §5.
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 for cloud AI insights; Bluetooth pairs with your phone.
Pressure & temperature
Notices when a window opens or you change floors.
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 (2 m) cable and 18W supply included.
Off-board connections
Sockets for the air-quality sensor, display, LED ring, and speaker.
Drag to rotate · scroll to zoom · labels track the components as you turn the board
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.
- Good
- Moderate
- Unhealthy for
Sensitive Groups - Unhealthy
- Very
Unhealthy - Hazardous
Specifications
By the Numbers
Sensor accuracy, power profile, mechanical and environmental conditions, lifted directly from the published datasheet.
- CO2
- IAQ
- PM1.0 / PM2.5 / PM4.0 / PM10
- VOC index
- NOx index
- Temperature
- Humidity
- Barometric pressure
- Ambient light
- AI insights
- Mobile app
- Web dashboard
Full technical specifications
Sensors
| Parameter | Sensor | Range | Accuracy |
|---|---|---|---|
| CO2 | Sensirion SEN66 (photoacoustic) | 400–5,000 ppm | ±50 ppm + 2.5% reading |
| PM1.0 / PM2.5 / PM4.0 / PM10 | Sensirion SEN66 (laser scattering) | 0–1,000 µg/m³ | EPA AQI-aligned |
| VOC index | Sensirion SEN66 (Sensirion VOC algo) | 1–500 | per Sensirion VOC spec |
| NOx index | Sensirion SEN66 (Sensirion NOx algo) | 1–500 | per Sensirion NOx spec |
| Temperature | Sensirion SEN66 | -10–50 °C sensing; rated accuracy 15–30 °C | ±0.5 °C typical (within rated band) |
| Relative humidity | Sensirion SEN66 | 0–100% sensing; rated accuracy 30–70% | ±4.5% RH typical (within rated band) |
| Barometric pressure | Bosch BMP390L | 300–1,100 hPa | ±0.5 hPa |
| Ambient brightness | TI OPT3001 | 0.01–83,000 lx | photopic-matched |
Power
- Input
- USB Type-C with Power Delivery negotiation
- Supported profiles
- 5 V @ 3 A · 9 V @ 2 A · 12 V @ 1.5 A (18 W max)
- Typical draw
- ~6 W steady-state, ~12 W peak (~$8/year to run at US-average electricity rates)
- Also works from
- a standard 5 V USB port on your computer or hub
- Power path
- Genuine TI PD controller + UL-listed external adapter
In the box
- Device
- The Terrestream Indoor Air Quality Sensor
- Wall adapter
- 18 W USB-C Power Delivery adapter, UL-listed, with interchangeable US and Canada plug heads
- USB-C cable
- 2 m (6 ft) braided USB-C to USB-C cable, USB-IF certified for 60 W Power Delivery
- Field guide
- How to Breathe, by Bear, a printed illustrated booklet that explains every measurement in plain English
Audio
- Amplifier
- Class-D, MAX98357A
- Output
- 2 W into 8 Ω (typical at 10% THD+N, PVDD ≈ 5 V)
- Speaker
- 28 mm full-range, 8 Ω
- Interface
- I²S, monaural
Mechanical
- Dimensions
- 111 × 65 × 69 mm (W × D × H)
- Enclosure
- Precision-manufactured polymer, desktop form factor
- Display
- 3.5″ 320 × 480 RGB color LCD, 262 K colors, capacitive touchscreen
- Underglow LEDs
- 15 individually addressable RGB on a custom-tooled ring PCB
- Connectivity
- Wi-Fi (2.4 GHz, 802.11 b/g/n) · Bluetooth Low Energy (BLE 5.0) · USB Type-C
- Designed & assembled
- Boston, MA, USA from US and imported components (primarily Switzerland, Germany, and China)
Environmental
- Operating temperature
- 10 °C to 40 °C (limited by SEN66)
- Operating humidity
- 20% to 80% RH, non-condensing (limited by SEN66)
- Storage temperature
- 0 °C to 45 °C (limited by SEN66)
- Storage humidity
- 0% to 100% RH, non-condensing
- Placement
- Out of direct sunlight
Smart-home integrations
- Home Assistant
- Native integration with mDNS auto-discovery, twelve signals as separate entities, configurable polling
- MQTT
- Publishes to any broker on your network; works with Node-RED, OpenHAB, and custom automations
- Matter
- Via Home Assistant bridge: opens up Apple Home, Google Home, Amazon Alexa, and SmartThings without per-platform code
- REST & webhooks
- Local HTTP API plus optional push to your own endpoint when readings cross thresholds you define
Lifespan & Warranty
- Sensor lifetime
- Sensirion publishes a continuous-indoor-IAQ mission profile of > 10 years for the SEN66. Real-world drift is expected after ~5 years of continuous use; baseline-correction algorithms compensate within that window. See Terms §6 for the operational lifetime statement.
- Calibration
- CO2 uses Automatic Self Calibration (ASC), Sensirion VOC and NOx use baseline algorithms, and PM is factory-calibrated against TSI DustTrak™ DRX 8533. Verification, recalibration, and replacement responsibilities are described in Terms §6.
- Device warranty
- 1-year limited warranty from Aerodyne against defects in materials or workmanship
- FCC compliance
- FCC Part 15 Class B compliant via Supplier’s Declaration of Conformity; testing by E3C. Read regulatory disclosures.
Product datasheet
The one-page Aerodyne-authored datasheet for the device itself:
- Terrestream Indoor Air Quality Sensor · TSR50035DAI · May 2026 (PDF)
- Product spec sheet (PDF)
Vendor datasheets
The full published datasheets for the individual sensors inside the device:
- Sensirion SEN66 · CO2, PM, VOC, NOx, T, RH
- Bosch BMP390L · barometric pressure
- TI OPT3001 · ambient brightness
- Measurement evidence - primary-source-indexed stack explanation for SEN66, BMP390L, and OPT3001.
Vendor datasheets and integration notes take precedence over the values summarized here. Specifications subject to change. Errors & omissions excepted (E&OE).
Comparison
How It Compares
Compared on the job to be done
Terrestream is built for room decisions: what changed, why it likely changed, and whether to ventilate, filter, or leave the room sealed.
Compared on evidence
The table calls out published datasheets, sensor modules, local integrations, and calibration posture instead of only counting measurements.
Compared on context
The differentiator is not only the hardware list; it is live outdoor weather, AQI, pollen, smoke, and history fused into one recommendation layer.
| 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 | PM2.5 | ✗ |
| VOC index | ✓ Sensirion algorithm | ✓ Sensirion algorithm | ✓ Sensirion algorithm | ✓ not publicly disclosed | ✓ not publicly disclosed | ✓ Sensirion algorithm | ✗ |
| NOx index | ✓ Sensirion algorithm | ✓ Sensirion algorithm | ✓ Sensirion algorithm | ✗ | ✗ | ✓ Sensirion algorithm | ✗ |
| Display | 3.5″ color LCD, touchscreen | small OLED | light indicator only | ✗ | E-ink, small | ✗ | E-ink |
| Underglow color ring | 15-LED custom board | 11 RGB LEDs | color-coded light indicator | ✗ | ✗ | ✗ | ✗ |
| Indoor + outdoor data fusion | weather, AQI, pollen blended | ✗ | ✗ | ✗ | — | ✗ | ✗ |
| Published evidence | product datasheet + vendor datasheets | spec sheet + test report | product page + datasheet | product specs | product sheet + help docs | ESPHome docs | datasheet |
| Calibration posture | factory-calibrated SEN66 + baseline algorithms | test chamber report | factory-calibrated (not individually recalibrated) | not documented | longer-term radon / CO₂ calibration | module-level | automatic CO₂ calibration |
| Mobile app | ✓ included | web dashboard | ✓ Ruuvi Station | ✓ Free app (no documented paid tier) | ✓ | via Home Assistant | ✓ |
| Home Assistant | ✓ Native | ✓ Native Home Assistant integration | ✓ Home Assistant | ✓ First-party in HA Core | ✓ Official HA core (cloud polling) | ✓ Native (ESPHome) | ✓ Community (BLE, local) |
| MQTT | ✓ Native | ✓ (stock firmware) | ✗ | ✗ | Airthings for Business only | Custom ESPHome YAML (not native) | ✗ |
| Apple Home / Google Home / Alexa | via HA Matter bridge1 | via HA Matter bridge | ✗ | Google + Alexa + IFTTT (no HomeKit) | Google + Alexa + IFTTT + Homey (no HomeKit) | via HA Matter bridge | ✗ |
| Matter | via HA bridge1 | via HA bridge | ✗ | ✗ | ✗ | via HA bridge | ✗ |
| Subscription required | Optional (Pro tier) | 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 assembled / $138 kit | 149€ | $299 | $329.99 | $109.99 | $189 |
1 About our Matter support: Terrestream bridges to Apple Home, Google Home, Amazon Alexa, and SmartThings through the Home Assistant Matter integration. The sensor is not a Matter-native device, and we do not ship dedicated HomeKit / Google Home / Alexa apps. Native Home Assistant and MQTT integrations ship at launch.
Specs reflect publicly-listed manufacturer information verified on 2026-06-10. 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.
Archived competitor sources (verified 2026-06-10): AirGradient ONE · Awair Element · Airthings View Plus · Apollo AIR-1 · Aranet4 HOME · Ruuvi Air
Review the Terrestream measurement evidence for the SEN66, BMP390L, and OPT3001 evidence behind the device architecture.
FAQ
Common Questions
Quick answers. The full support hub at terrestream.com/support covers the rest.
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?
Pro is optional. All twelve signals, the on-device display, the underglow ring, and the basic mobile app are included with the device. The optional Pro tier unlocks longer trend history and advanced AI insights, but is never required for the device to do what it does.
Will it work without Wi-Fi?
Yes. Plug it in and the device measures and displays continuously. Wi-Fi is needed only for cloud features: long-term history, AI-powered insights, outdoor data fusion (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, 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. Sensor accuracy is maintained per Sensirion's published specifications across the sensor lifetime described above.
Does it integrate with my smart home?
Yes. Native Home Assistant integration ships at launch (auto-discovered via mDNS, twelve signals as separate entities). The device also publishes to any MQTT broker on your network, so it slots into Node-RED, OpenHAB, or your own automations. Through Home Assistant you can bridge to Matter, which opens up Apple Home, Google Home, Amazon Alexa, and SmartThings without us writing per-platform code.
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.
Plans
Free vs Pro
Everything the device does on your own network is free, forever. Terrestream's cloud adds a free tier, and an optional Pro tier for depth. Every device ships with 3 months of Pro.
| Capability | Free | Pro |
|---|---|---|
| On the device & your local network — always free | ||
| All twelve signals, on-device screen & 15-LED underglow | ✓ | ✓ |
| Works fully offline (Standalone mode) | ✓ | ✓ |
| Local HTTP API, Home Assistant & MQTT | ✓ | ✓ |
| Matter → Apple Home, Google Home & Alexa (bridged through Home Assistant) | ✓ | ✓ |
| Through Terrestream's cloud | ||
| Mobile app + web dashboard on every device | ✓ | ✓ |
| AI insights (Discovery cards), recommender & auto lenses | ✓ | ✓ |
| History retention | 90 days | Unlimited |
| Wellbeing & pet lenses, smart feels-like | — | ✓ |
| Family Circle (up to 6 members) | — | ✓ |
| Cloud-mediated smart-home automations | — | ✓ |
| Wrapped, Air Ghosts & sleep-stage correlation | — | ✓ |
Pro price is shown at signup and varies by region. Full breakdown: Free vs Pro feature matrix.
Founder beta
Evaluating an early unit for a real home?
We are reserving a small number of early deployments for households that will give direct feedback on setup, placement, alerts, and the app workflow. This is a fit review through the sales contact pipeline, not a waitlist.
Breathe Better. Live Smarter.
Bring Terrestream into your home.
One sensor. 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- 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, USB-C cable, power adapter, and printed field guide
- Dashboard and mobile app included
- Privacy-first air data
Works with
- Home Assistant
- MQTT
Home Assistant
MQTT