Know what you're breathing.
A tiny air monitor that lives on your keys. Press the button and read the light: green means the air is fine. Red means it isn't. For the office you came back to, the classroom your kid sits in all day, and the smoke that rolls in every summer.
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You can't see bad air. You spend all day in it anyway.
The air-quality number on your phone comes from a government station that can be miles away, outdoors, on a roof. It knows nothing about the conference room with no windows, a classroom with thirty kids in it, or your kitchen at dinner time. We spend nearly all our time indoors, and indoor air is almost never measured.
You didn't pick the building.
Return-to-office means trusting ventilation you've never seen, in meeting rooms that were stuffy before the word "aerosol" meant anything. Bring your own answer.
Kids feel it first.
Children breathe faster than adults and are more sensitive to fine particles. Check the drop-off line, the gym, the classroom after recess: the places they spend their whole day.
Smoke doesn't follow forecasts.
Wildfire haze arrives street by street. It lingers indoors long after the sky looks blue — this tells you when it's actually gone.
"I had asthma as a kid, in a home full of smoke that nobody measured. This is the thing I wish my family had."
Early-bird pricing goes to this list first.
PocketWatch Air launches on Crowd Supply, the crowdfunding site for open hardware. Join the list and you'll get first crack at early-bird pricing, plus word when the first units come off the line and when the independent review is published.
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What the light is telling you.
No app needed in the moment. A small light gives an instant answer, using the same health guidance behind the official air-quality index. When you want the full numbers, they sync quietly to your phone.
Green — breathe easy
Particle levels and air chemistry look healthy.
Amber — take note
Elevated readings. If you're with young kids, or anyone with asthma, keep the visit short.
Red — act
Unhealthy air. Close the window, step out, or mask up.
Your whole day, mapped to air.
Every reading is stamped with the time and place it was taken. The app lays them out as your day: overnight at home, the spike on the subway platform, the office afternoon, the burst when dinner hits the pan. Once you can see the pattern, you can change it — open a window, move the desk, pick the other train.
App screens are a design concept. The app ships alongside the device.
The air report for where you actually are.
It clips to your keys and weighs about as much as a car fob, so it's with you at the school run, on the subway platform, in the office, at home. No fan inside means it's completely silent and there's nothing to clog. A single charge lasts for months of daily checks.
When the smoke rolls into the job site.
California's Cal/OSHA wildfire-smoke rule (§5141.1) has employers act once the PM2.5 air-quality index reaches AQI 151 — about 55.5 µg/m³: check the air each shift, tell the crew, and offer N95s. The rule even lets employers measure PM2.5 themselves. PocketWatch Air reads that exact number — on every worker, at the actual worksite, not a station miles away.
A read on every worker.
Clip one to each crew member. Press for an instant, personal PM2.5 read and a color verdict — a monitor per worker, at the price of one for the whole site.
A signed shift record.
Plug it into USB-C at the trailer or dock and it runs the whole shift, logging a rolling 12-hour trend. Every record is cryptographically signed, so your log is tamper-evident.
See the line before you cross it.
Thresholds vary by state — California acts at AQI 151, Oregon around 101, Washington around 72. Watch the number climb toward yours in real time.
Situational awareness, not a compliance instrument. PocketWatch Air is a low-cost PM2.5 sensor that supports — but does not replace — an employer's Cal/OSHA §5141.1 obligations or the official AQI from AirNow or your local air district.
Design complete
Second-revision hardware, engineering and safety reviews passed.
Pilot in fabrication
A 10-unit pilot run is on order at the board house.
Bench validation
Bring-up, sensor accuracy and battery life on real hardware.
Independent review
Neutral third-party hardware and security review, then the design goes public.
Crowd Supply
Campaign launch. The waitlist hears first.
What's inside.
Most pocket monitors cut a corner somewhere — a fan that clogs, or a sensor that misses the smallest particles. Here's what we put in instead.
No fan. Nothing to clog.
Bosch's BMV080, the smallest fanless particle sensor made, reads PM1, PM2.5 and PM10, including the ultrafine PM1 fraction most rivals can't see.
The full air picture
A Sensirion SGP41 adds VOC and NOx air-chemistry indices; an SHT40 adds temperature and humidity. Particles, chemistry and comfort in one reading.
Readings you can verify
The ATECC608B secure element signs each reading on the device as a C2PA Content Credential — proof of where a measurement came from and that it wasn't changed. More below ↓
Built to carry
Nordic nRF52840 with Bluetooth LE to your phone, USB-C charging, and a user-replaceable battery. Deep sleep between readings stretches a charge for months.
Readings you can prove.
Every reading is signed on the device the moment it's taken, as a Content Credential — the open C2PA standard (contentcredentials.org) that news photos and AI images now use to prove where they came from. PocketWatch Air is one of the first consumer sensors to carry that credential on its data.
The number can't be altered
The signature covers the exact reading. If a value is altered on its way to your phone or a shared map, the check fails — the number you see is the number the device measured.
It really came from the device
Each unit signs with its own identity, so a reading can't be faked by a look-alike gadget or a script. A community air map is only as useful as its data is real.
Anyone can check it
C2PA is backed by camera makers, Adobe and the news industry, and standard tools read a Content Credential without our permission. We publish how ours are built.
Signing proves a reading is authentic and unaltered — it doesn't lock your data away; you decide where it goes. It confirms where a measurement came from, not whether the air is good or bad. Pilot units carry a development certificate; production units get a per-device certificate and join the public C2PA trust list, so any standard tool can verify them.
You'll get to see all of it.
We designed the whole board ourselves — four layers, drawn in KiCad, with a teardrop outline, an integrated keyring, and a battery system with proper charging, protection and fuel gauging.
The complete design — schematics, PCB, enclosure, and firmware — will be published as open source once an independent hardware and security review by a neutral, respected third party is complete. We want the first public release to be one you can audit and trust.
Hardware under CERN-OHL-S v2, firmware open, one honest caveat: the Bosch BMV080 sensor ships with a proprietary driver blob we're not allowed to redistribute. Everything around it is open. Compliance work (FCC Part 15B, FDA laser notice, battery and enclosure safety) is scheduled ahead of any sale.
KiCadCERN-OHL-S v2OSHWnRF52840 · BLE 5.4USB-C