Usually a hub of freeway ramp traffic, data shows a central neighborhood now approaches San Francisco’s average.
So much of the outdoors has changed for the better since the gloom of pandemic arrived: quieter streets, more birds. The air quality in Hayes Valley has been so notcieably good since the city’s shelter-in-place order went into effect back in mid-March that I wanted to see how much better it really was.
Hayes Valley is a central neighborhood, once the site of a huge double-decker freeway bypass and today a traffic sewer of cars backed up Oak and Octavia to get on the 101 and backed up on Octavia and Fell to get off it. Add high volume north/south transit on Laguna and Buchanan and it’s easy to see why tailpipe emissions accumulate here.
The coronavirus situation has created an incredible natural experiment opportunity. I used the hyper-local data available from Purple Air’s excellent citizen-contributed sensor map to create two sets of data streams: one representing the city overall through the average of many outdoor sensors from around the city; and another representing Hayes Valley through the average of several local sensors. (Disclaimer: I’m not a scientist or statistician, see methodology at the end if you want to know more.)
