Low-Cost Sensor Platform Guide, Part 1
By Sruti Modekurty, OpenAQ Platform Lead
We have been hard at work for the past year working on this major addition to the platform and we are so excited to finally share it with all of you! Below, you will find a summary of what’s new and what’s different as well as more detailed guides on website and API updates.
- New kinds of data — low-cost sensor, mobile, extra parameters
- Dashboards on website give overview of data
- V2 API with low cost sensor data and improved performance
- Access all of the data through the API
- Updated data type definitions
- Slight V1 API differences
- API docs are interactive
*New* Data Type Definitions
With the addition of data from low cost sensors, we have redefined how we categorize data. Previously, the ‘sensorType’ attribute was either ‘government’, ‘research’ or ‘other’. Now, we have ‘sensorType’ as either ‘reference-grade’ or ‘low-cost sensor’ to refer to the kind of instrument collecting the data. We have added another attribute called ‘entity’ which can be ‘government’, ‘research’ or ‘community’. This is to allow greater flexibility in how data is labeled, recognizing that groups, from governments to researchers, are increasingly using both reference-grade and low-cost sensors. Governments are launching low cost sensor networks and research groups may employ both reference and low-cost sensors. What was previously labeled as ‘sensorType = government‘ (which was pretty much all of the data on the platform), is now ‘sensorType = reference’ and ‘entity = government’.
For more information, read the detailed definitions of data on Github.
If browsing for data through the website, you can filter using the following
*New* Extra Parameters Available
In addition to our core parameters (PM2.5, PM10, CO, O3, NO2, SO2), we now have extra parameters available for a limited set of locations sourced by EDF and PurpleAir including PM1, PM1 counts, PM2.5 counts, PM10 counts, CH4, CO mass, CO2, NO, NOx, NO2 mass, O3 mass, SO2 mass, UFP count. While we recognize other sources may be reporting some of these additional parameters, we do not have those available on the platform at this time.
*New* Mobile Data Available
Previously, all data on the platform was collected through stationary monitors. With the addition of low cost sensor data, we now have mobile monitors from EDF and HabitatMap. Mobile monitors can collect data for multiple locations, allowing for greater range and flexibility.
The world map has always been a page to get a bird’s-eye (well maybe more like a satellite’s-eye) view of data available through the platform. In addition to reference data as circles, you can now see low cost sensor data as squares. Clicking on one will take you to the dashboard for that location.
The locations page has been updated with new filters to make it easier to search for data and location cards have been updated with tags such as ‘Low cost sensor’, ‘Community’, ‘Mobile’ for easier identification of data types. Clicking ‘View More’ on a location card will take you to a Dashboard for that location.
The new Locations Dashboard (a redesigned version of the Locations page with way more functionality) gives you an overview of the data from a location. It allows you to get quick stats about the data including number of measurements, recent values, source information and more. Each location is tagged with a unique ID so you can easily reference and access data for that location. For example, the ID for Concón in Chile is 27.
The dashboard also displays time series charts for the past week of data and temporal coverage charts for all parameters available. The parameters table gives average values and counts for all parameters as well.
[Screenshot of Locations dashboard, graphs + table]
By default, the dashboard displays information for all the data available from that location. You can specify a time window for which you would like to view stats and graphs in the upper left corner.
For example, this recalculates the time series chart to display hourly averages for the month of January 2021.
As usual, you can see other nearby locations at the bottom of the dashboard.
For data from a mobile sensor, the dashboard will show a bounding box for all the locations where measurements were collected, like the following example of a Google Street View Car from the Breathe London Project.
The datasets page is a new addition to the website. A dataset groups locations managed by the same source which share similar characteristics. Right now, that means standardized deployment practices, data post-processing and quality assurance — all of which are documented in related metadata and a technical Readme, and which are unique to the data sets currently included on the datasets page. Datasets allow for additional exploration of air quality across comparable locations within the same network. We are exploring expanding the definition of a dataset and would love your feedback!
The Datasets Dashboard shares similarities with the Locations Dashboard, with some notable differences.
Datasets with stationary data allow you to select specific locations out of the dataset to regenerate the stats and charts. Click on each square in the map and click ‘Select Location’ to choose locations. Click ‘View Location Data’ to update the stats and charts.
Many of the current datasets contain ‘Analysis’ data meaning it has undergone cleanup and post-processing, the details of which can be found in the Technical Readme. For Analysis Datasets, the Time Series and Temporal Coverage charts are not available. Instead, a map of all the measurements are shown.
That’s it for the website updates! This is a pilot, so we are really looking for feedback on the platform, and would appreciate it if you could take a few minutes to fill out this short survey.
Stay tuned for Part 2, which will cover API updates and platform architecture changes.