Frequently Asked Questions

What is STAIR?

STAIR is a consumer-grade air quality monitoring service. Our devices are equipped with sensors that measure particulate matter of various granularity (PM1, PM2.5, and PM10), as well as temperature, humidity, location and timestamp data. Devices will send sensor data to our servers, which are updated in real time to report the most up-to-date information.

How does it work?

When a sensor collects environmental data, it publishes that information to Amazon Web Services using secure MQTT. This network protocol provides mutual authentication, message encryption, and message integrity between the sensor and the server. AWS also manages our database and web server infrastructure using DynamoDB and Elastic Compute Cloud. We use the Google Maps JavaScript API to build our map and Google Charts API to show data history to users.

What sets it apart from other air quality monitoring services?

At STAIR, our highest priority is to provide security and privacy to its users. In fact, our team is mostly comprised of researchers who study security for a living. Our research has shown that some contemporary air quality services are susceptible to attacks - see this publication for more details. By comparison, our sensors are designed with microcontrollers that implement data encryption, secure firmware booting, and hardware-rooted data storage. All network transmissions use Transport Layer Security. In this way, our service guarantees high reliability and tamper resistance.

How can I purchase a sensor?

Unfortunately, STAIR sensors are not currently for sale. We will update this website as soon as they become available.

How does STAIR uniquely identify my device?

Each device internally generates a unique device identifier. The identifier is computed from the hash of the device private key (which is also unique to each device). This identifier is sent to AWS along with any environmental data. To mitigate against spoofing attacks, STAIR will never publicly expose your identifier to anyone.

Why don't my sensor readings show up on the map?

We currently only display the last 48 hours of sensor data. If your readings don't show up within 2 minutes, make sure your sensor is connected to WiFi. If the problem persists, contact the administrator.

Why do I see three sensor values?

There are three individual sensors in each unit. If one sensor is much higher than the other two, the high sensor is probably not working correctly. Sensor values within 1-20 ug/m3 of each other are usually correct, but values 100s - 1,000s ug/m3 different typically indicate one sensor is not working correctly and does not represent a real change in air quality.

For any other questions, contact the site administrator at