Davis AirLink: What It Measures and How to Put It Online
By Lennart Steen · Hands-on guides from the people building the platform
The Davis AirLink is the air quality sensor of the Davis ecosystem: a laser particle counter that reports PM1, PM2.5 and PM10 continuously into your WeatherLink account. It is also the Davis device people misunderstand most, because it is not an add-on to a station. It is a standalone sensor, often registered as a station of its own, and that quirk used to make publishing it awkward. This guide covers what it actually measures, how it fits into an account, and how the readings end up on a website of your own, in the index your visitors recognise.
What does the Davis AirLink measure?
The AirLink measures airborne particulate matter in three size fractions, PM1, PM2.5 and PM10, alongside its own temperature and humidity readings. Inside is a laser particle counter: a small fan draws air through a chamber where a laser beam illuminates it, particles scatter the light, and a photodetector counts and sizes them. From those counts the sensor reports concentrations in micrograms per cubic meter (µg/m³), continuously.
Just as important is what it does not measure. The AirLink counts particles only; it does not detect gases such as ozone or nitrogen dioxide, and it has no CO2 sensor. Official air quality indices fold in gas readings from government monitors, so on a high-ozone summer day the official index for your area can read worse than your PM-only value suggests. The measurement principle, along with every other sensor on a station, is covered in how weather station sensors work.
What do PM1, PM2.5 and PM10 actually mean?
Each is a size cutoff, not a different pollutant: PM2.5 means every particle smaller than 2.5 micrometers across. The three fractions matter differently for health.
| Reading | Particle size | Why it matters |
|---|---|---|
| PM1 | Under 1 µm | The finest fraction the sensor separates out |
| PM2.5 | Under 2.5 µm | The standard health measure; small enough to penetrate deep into the lungs and enter the bloodstream, and the reading every AQI standard is built on |
| PM10 | Under 10 µm | Captures coarser dust and pollen |
PM2.5 is the number to watch. It is the basis of both the US and European indices, it is the value air quality alerts trigger on, and under the 2024-updated US EPA breakpoints anything up to 9.0 µg/m³ counts as "Good."
How does the AirLink fit into a Davis setup?
As a standalone device, not an accessory to a particular station. The AirLink joins the same WeatherLink account as your weather station and works alongside either a Vantage Vue or a Vantage Pro2; it is not a Pro2 exclusive, which surprises Vue owners weighing an upgrade. If you are still choosing between the two stations, the Vue vs Pro2 comparison covers that decision; the AirLink question is independent of it.
There is one wrinkle worth knowing before you buy: an AirLink bought separately is usually registered in WeatherLink as its own station rather than as a sensor on your existing one. Your account then holds two entries, a weather station and an air quality station, and anything reading the account has to be smart about stitching them together.
What if your AirLink is registered as its own station?
On Pro Weather, nothing breaks and nothing needs working around: the site reads the particulates from wherever they actually are. Your site renders one station (the one you pick under Panels, normally your weather station) and pulls the air quality readings from the AirLink entry, so the tile, the tab, the charts and your PM2.5 alerts all work without you choosing between the two.
This matters if you set it up in the past. Some owners pointed their site at the AirLink station just to get air quality showing at all, and lost temperature, wind and rain in the bargain. If that was you, switch the station setting back to your weather station: air quality follows on its own now, and the weather readings come back with it. The details live in the air quality docs.
If you would rather have everything arrive as one single station, a relay does that too: weewx, Meteobridge or CumulusMX reading both the console and the AirLink, posting one combined upload to your site's hardware ingest URL. The ready-made upload templates there already carry the particulate fields, and the CumulusMX one includes the 24-hour means and NowCast values the AirLink computes itself, which are used in preference to deriving new ones.
How do you put AirLink data on your own website?
Through the same free WeatherLink v2 API key as the rest of your Davis gear, with no separate setup for the sensor:
- Connect your WeatherLink account with a free v2 API key. Pro Weather auto-discovers every station and sensor on the account, AirLink included.
- If you add the AirLink later, open Connection and choose Reconnect & rediscover.
- The air quality tile and tab appear as soon as particulate readings arrive.
What visitors then see: an Air quality tile in the Overview grid and a dedicated tab, the current index colour-coded on the band scale of whichever standard you chose, the main pollutant behind it (PM2.5 or PM10), live PM1, PM2.5 and PM10 concentrations in µg/m³, and a historical chart with the same range switcher as the other tabs. The panel updates every 5 minutes alongside the rest of your data. Start a free 14-day trial and the sensor is discovered in the first minute of setup.
Your readings can also feed outward: Pro Weather uploads PM2.5 and PM10 to Weather Underground when an AirLink is on the account, as part of publishing to weather networks.
Which AQI standard should your site display?
The one your audience already knows, and that is exactly why there are eight to choose from. The same PM2.5 concentration lands in very different categories depending on the scale: air at 30 µg/m³ is "Poor" on the European EAQI but only about 90, still "Moderate," on the US EPA scale. Show a US audience the EPA index and a European audience the EAQI, and nobody has to translate.
| Standard | Where it is official | Scale |
|---|---|---|
| European AQI (EAQI), the default | European Union | Six named bands, Good to Extremely poor |
| US EPA AQI | United States | 0-500, six colour-coded categories |
| UK Daily Air Quality Index (DAQI) | United Kingdom | 1-10 in four bands |
| Common AQI (CAQI) | European cities | 0-100, urban-background scale |
| Canada AQHI | Canada | Health-risk index, 1-10+ |
| Australia NEPM | Australia | Ratio scale where 100 is the national standard |
| Luchtkwaliteitsindex (LKI) | Netherlands | 1-11 |
| BelAQI | Belgium | 1-10, every level with its own name |
Whichever you pick, the index is computed from your own PM2.5 and PM10 readings and the worse pollutant sets the headline. One honest edge case: Canada's AQHI formula has no PM10 term at all, so a sensor reporting only PM10 shows no index under that standard rather than an invented one. And a note on averaging: most standards are officially defined on 1-hour or 24-hour means, while your sensor reports live values, so your panel tracks the breakpoints in real time rather than issuing a regulatory determination. The full US vs European story, including the EPA's tightened 2024 breakpoints, is in AQI vs EAQI explained.
What is the Ecowitt alternative to the AirLink?
The WH45 and WH46 modules, and they bring one thing the AirLink does not have: CO2. Both modules measure particulates and carbon dioxide along with their own temperature and humidity, and they reach your site through the Ecowitt gateway's Customized upload rather than through a cloud API. If you run Ecowitt, Froggit or Ambient Weather hardware, that path is a five-minute copy-paste job covered in the Customized upload walkthrough.
On the site itself the result is the same: the identical air quality tile, tab and choice of eight standards, computed from your own readings. So the decision is really about ecosystem, not capability. Davis owners add an AirLink to the account they already have; Ecowitt owners add a WH45 or WH46 to the gateway they already have; and only the Ecowitt route also puts a CO2 number on the page. The full brand-by-brand picture is on the supported hardware list.
Common questions
Does the AirLink measure ozone, NO2 or CO2?
No. The AirLink is a laser particle counter, so it measures particulate matter plus temperature and humidity, nothing gaseous. Official AQI figures also fold in ozone and nitrogen dioxide from government monitors, which is one reason your PM-based index and the official one for your city can disagree. If CO2 matters to you, the Ecowitt WH45/WH46 route is the one that measures it.
Does the AirLink work with a Vantage Vue?
Yes. The AirLink is a standalone device that joins the same WeatherLink account, so it works alongside a Vue exactly as it does alongside a Pro2. It is not tied to either station.
Can you get an alert when the air turns bad?
Yes. Add a PM2.5 above threshold to your site's alerts and you hear about poor air even when you are not watching the page, which earns its keep during wildfire smoke events. Air quality accounts for three of the more than forty alarm conditions, and every alarm can deliver by email, a signed webhook, or both. Setup is covered in weather alerts for your home station.
Why does your AirLink index differ from the official one for your area?
Three usual reasons: a different index (US AQI, EAQI, or another of the eight), a different averaging window (official values smooth over hours while your sensor reports near-instantly), and gases, which official monitors include and a particle counter cannot see. Placement matters too; a sensor next to a road or barbecue reads worse than one in a clear garden.
Do you need an AirLink at all if you already run CumulusMX or Meteobridge?
You still need the sensor, but not a new pipeline. Both programs can read an AirLink directly (CumulusMX under its AirLink settings, Meteobridge as a station by IP address) and relay the particulate fields to your site inside their normal upload, so the AirLink you already have keeps feeding everything downstream.