Solarcast Deployment: Los Angeles

Earlier this year we announced Solarcast and talked about some of the challenges we faced while designing it. Thanks to the generous support of the Annenberg Foundation & Metabolic Studio (as well as the longterm support of the Shuttleworth Foundation) we were able to create the first batch of these devices and have been deploying them in Los Angeles. The data coming in from these is now accessible via the Safecast API and can be queried along with everything else. These devices are solar powered and cellular connected, so they are sending in data all the time and they power themselves. This is a huge improvement from our previous Pointcast devices that required both power and connectivity in any location they were placed. This also makes Solarcast more portable, so we can do fun things like deploy them on every house on a single block, and then a week later expand that out to 2 blocks, and so on without having to think about complicated installations.

As the Solarcast sensors collect a lot more data than our previous radiation-only devices, we had to rethink how we’d represent these devices on our maps. The results of that is live now in our primary web visualization (air quality + radiation) as well as realtime (radiation only) maps.

The icons for the Solarcast sensors jump out right away and need a little further explanation. We wanted to quickly convey a lot of things to the viewer without confusing people with too much info right away. We decided on this “3 triangle” icon to do just that. The center triangle represents the current particulate (air quality) reading, with the two triangles in the background showing the lowest (left) and highest (right) readings from the last 24 hours. The angle of the 3 triangles represents the current trend, whether the levels are increasing or decreasing at the moment. If you want more info, clicking on the icon for any individual sensor gives you additional graphs.

On the left we show readings from the last 24 hours, and on the right from the last 30 days. Each reading from each sensor is broken out here as well so you can get a really quick view of what’s going on and any trends that may be emerging. A quick note on the particulate sensors: as we mentioned in the announcement post, there are two particulate sensors in each Solarcast unit, each measuring at 3 different sizes (PM10, PM2.5 and PM1.0) resulting in 6 individual air measurements with each “reading.” A higher end sensor produced by Alphasense and a lower end sensor produced by Planttower are deployed in serial so that we can see the relationships between these two sensors and their readings. Measuring particulate is still a bit confusing because while terms like PM2.5 are commonly used in the press these days, there is no standard of what PM2.5 is exactly, so each sensor manufacturer decides on their own what they will consider PM2.5 for their purposes, and most often are not transparent about how they make that decision as they consider it to be a valuable trade secret. The result of this, as you’ll see reflected in our data, is that two sensors right next to each other will show different readings for the same metric. As co-founders of The Air Sensor Workgroup (along with EDF, EPA, Google, Alphasense and others) this lack of transparency and shared standards is one of the major problems we hope to address, and in the meantime having better data showing how different sensors react in the same environments will go a long way to understanding what these readings mean.

An exciting development with these visualizations is that you can now see, in realtime, how different parts of the city have different air quality, and how markedly that changes from one location to another.

While our web map is feature-packed and can be highly customized to display the things you are interested in, we also have a realtime radiation map which is singularly focused and specific showing realtime radiation data only. Please note, the colors of the icons here represent the “health” of the sensor, that is, when we last received data from it – not the reading from the sensor. Blue sensors are online, yellow were recently online and red have been offline for a while. You can click further in for more details and readings from the sensors.

We currently have 20 Solarcast sensors deployed around Los Angeles, with some additional units around the world (zoom out and see if you can find them).

We’re excited about this deployment, and the flexibility of the Solarcast platform will allow us to relocate these sensors on an ongoing basis to zero in on areas of interest. We’re also working to secure funding for a larger deployment and hope to place another 50 sensors in the near future. If you are interested in following the progress here, please be sure to join our mailing list and follow us on twitter, and of course donations are always welcome.

About the Author

Sean Bonner


Sean Bonner is a co-founder and Global Director of Safecast. Based in Los Angeles, he's an Associate Researcher at the Center For Civic Media at the MIT Media Lab and a Shuttleworth Fellow.