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 index
on at 51 AQI
Good Moderate Unhealthy Hazardous

Running a purifier nonstop eats through filters in a few months and wastes electricity on days when the air is completely fine. Turning it off entirely means breathing smoke during wildfire season or sitting through whatever inversion your city gets in winter. And manually checking AQI and remembering to flip a switch? That's a habit nobody keeps.

AirMonitor takes care of it. When the AQI climbs above your threshold, the purifier turns on. When the air clears, it turns off. Your dashboard shows a log of every switch.

Blue air purifier
Requirements

Three things to get started

Kasa smart plug

The EP25 ($17) is what I use. It has energy monitoring built in so you can see exactly how much power your purifier draws. The EP102 (~$7) works fine if you just need on/off.

Kasa account

You'll need a free TP-Link account paired to your plug. We encrypt your login and only use it to control your device.

Nearby PurpleAir sensor

PurpleAir has thousands of community sensors across the country. Enter your address and we find the nearest outdoor one.

Setup

Five minutes to set up, then nothing

1

Plug in your purifier

Connect your air purifier to a Kasa smart plug. The EP25 (~$17) has energy monitoring; the EP102 (~$7) is the budget pick. Any Kasa plug with on/off control works.

2

Enter your Kasa credentials and find a nearby sensor

Log in with your TP-Link email and password. Enter your address and pick a nearby PurpleAir sensor from the list. If you have an indoor sensor too, you can add that.

3

Subscribe and forget about it

We check air quality every five minutes. When the AQI goes above 51 your purifier turns on. When it clears, it turns off. You can adjust the threshold from your dashboard.

The math

It pays for itself

Purifier filters are rated for 6-12 months of continuous use. Run it only when the air is actually bad and that cost drops. If you're in California, the Pacific Northwest, or anywhere that gets real wildfire smoke or winter smog, you already know how often that is.

$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 by Stripe. We don't store card numbers. Cancel anytime from your account.

$1.50
per month
  • Checks every 5 minutes
  • Outdoor + indoor sensor support
  • Adjustable AQI thresholds
  • Activity log
  • Cancel anytime
$10
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?
Default is 51 AQI for outdoor sensors. If you add an indoor sensor, it defaults to turning on at 30 and off at 15. The gap between on and off prevents it from cycling when air quality sits right at the threshold. You can change all of these 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?
For now, just Kasa (TP-Link). It's what I use and it has a reliable API. Other brands might be added later.
Is my Kasa password stored securely?
Yes. Your credentials are encrypted before they're saved. They only get decrypted when we need to control your plug, and we never log them. The service runs on my own server.
Who built this?
This started as a personal script I've been running for my own purifiers (a small Blue unit and a Carrier) using PurpleAir sensors inside and outside my house. It's been running reliably for a couple years, so I turned it into something other people can use too.