Run your air purifier
when the air is bad.

Connect a Kasa smart plug to real-time PurpleAir data. We check air quality every five minutes and switch your purifier on or off automatically. No app to check, nothing to remember.

See how it works
PM2.5 air quality purifier turns on at 30 AQI
Good Moderate Unhealthy Hazardous

Running a purifier 24/7 burns through filters every few months and draws power around the clock. Turning it off entirely means breathing smoke on wildfire days, sitting in valley fog in winter, or dealing with whatever your local air quality brings. The right answer is somewhere in the middle -- but manually checking air quality and flipping a switch is a habit nobody actually keeps.

AirMonitor does it for you. When conditions drop below your threshold, your purifier turns on. When the air clears, it shuts off. You get a log of everything that happened.

Requirements

Three things to get started

Kasa smart plug

The EP25 ($17) is the one we use. It has energy monitoring so you can see exactly what your purifier draws.

Kasa account

A free TP-Link account tied to your plug. We store your credentials encrypted and use them only to control your device.

Nearby PurpleAir sensor

There are thousands of sensors on the PurpleAir map. We find the closest outdoor one to your address automatically.

Setup

Five minutes to set up, then nothing

1

Plug in your purifier

Connect your air purifier to a Kasa smart plug. The EP25 costs about $17. Any Kasa plug with on/off control works.

2

Enter your Kasa credentials and find a nearby sensor

Type in your TP-Link email and password. Enter your address and we pull up a list of nearby PurpleAir monitors -- pick the closest outdoor one, and optionally an indoor one if you have it.

3

Subscribe and forget about it

We check air quality every five minutes. When PM2.5-based AQI goes above 30, your purifier turns on. When it drops below 15 and stays there, it turns off. You can adjust both thresholds from your dashboard.

The math

It pays for itself

Most purifier filters are rated for 6-12 months of continuous use. Running only when air quality drops below threshold can cut that cost significantly. If you live somewhere with real seasonal events -- California wildfire smoke, Pacific Northwest haze, winter inversions in valley cities -- you probably already know how often the air gets bad.

$30-60
Filter replacement per year, running constantly
~half
Typical filter savings when running only when needed
$10
AirMonitor yearly subscription
Pricing

Simple and cheap

Payments are handled through PayPal. We don't store card numbers. Cancel anytime from your PayPal account.

$1
per month
  • Checks every 5 minutes
  • Outdoor + indoor sensor support
  • Adjustable AQI thresholds
  • Activity log
  • Cancel anytime
$10 2 months free
per year
  • Checks every 5 minutes
  • Outdoor + indoor sensor support
  • Adjustable AQI thresholds
  • Activity log
  • Cancel anytime
Questions

FAQ

How often does it check air quality?
Every five minutes. PurpleAir sensors update roughly every two minutes, so five-minute polling catches changes without hammering the API. If there's a rapid air quality spike, you'll see a response within ten minutes at most.
What AQI level triggers it?
Defaults: turns on when indoor AQI crosses 30, turns off when it drops below 15. The gap between those two numbers prevents it from cycling on and off when air quality hovers around the threshold. You can change both from your dashboard.
Do I need an indoor PurpleAir sensor?
No. You can run on outdoor readings alone. An outdoor sensor is enough to catch wildfire smoke events and similar episodes. An indoor sensor helps if you have specific indoor sources (cooking, candles) or want finer control, but it's optional.
What if my Kasa plug or PurpleAir sensor goes offline?
We log the error and skip that cycle. We don't force the purifier on or off if we can't get a reading. The next successful cycle picks up normally. Your dashboard shows any errors that came up.
Can I use any smart plug brand?
Right now, Kasa (TP-Link) only. It has a straightforward cloud API. Support for other brands may come later.
Is my Kasa password stored securely?
Yes. Credentials are encrypted at rest using AES-128. They're decrypted only at the moment we need to call the Kasa API, and they're never logged or shared. The service runs on a private server, not a shared cloud platform.
Who built this?
This started as a personal script I've been running for my own air purifiers -- one small Blue unit and one Carrier -- using PurpleAir sensors inside and outside my house. It's been running reliably for a couple of years, so I built it into something others can use.