A PurpleAir sensor is an "Internet of things" (IOT) air quality sensor or particulate monitor consisting of the following elements:

PMS1003 Laser Particle Counter:

PurpleAir uses PMS1003 laser particle counters. These sensors count suspended particles in sizes of 0.3, 0.5, 1.0, 2.5, 5.0 and 10um. These particle counts are processed by the sensor using a complex algorithm to calculate the PM1.0, PM2.5 and PM10 mass in ug/m3. PMS1003 sensors come factory calibrated.
Before deploying any devices, we verify that they are giving out readings that are consistent from sensor to sensor during tests in a smoke chamber.

So far, all sensors we tested have produced consistent output.


ESP8266 and Arduino:

Purple Air sensors use an ESP8266 chip to talk to the particle counter and provide all functionality, including connecting to a WiFi network and uploading data to the cloud. This ESP8266 chip runs code developed using Arduino. Purple Air firmware has remote update features meaning we can modify the software and the device will download the new version and update itself. Each device checks for updates from time to time.

Thingspeak.com and HighCharts.com:

Thingspeak.com provides the cloud storage for the data and allows us to to access it later for graphs. These graphs use HighCharts.com.

Google:

Using services from Google makes for a robust, reliable and secure system.
Google maps provides the map interface.
Google scripting provides the processing power to place the sensors on the map and create the graphs and other elements to display the data.

Other Sensors:

Some Purple Air monitors include temperature and humidity sensors. Where these are present, there will be graphs for these values. The temperature values may be elevated due to the case and other factors that do not provide ideal temperature monitoring. These values are provided as is and are just for interest.
Purple Air sensors may include other detectors in the future like Ozone or other gases.

Other Hardware:

Purple Air sensors are housed in a Stevenson screen, allowing air to flow through into the sensor while protecting the electronics from the elements.
Stevenson screens are typical for an outdoor sensor like this but we use a novel design and components.

Purple Air monitors are powered by a standard USB power adapter.