This is behind a paywall, / sign in so I can’t read it. However, nothing the US does now surprises me any more. It will be a big loss.
Yes, this is a huge loss but I still have some hope they will get back online.
By the way, we are trying to fill the void a bit. This is what I posted on LinkedIn yesterday:
The US Embassy AQ Monitors went Dark. We’re here to reboot it! 
We are working on a few projects in the Global South using data from the US embassy monitors to calibrate our open-source air quality monitors. These are countries without any publicly available reference stations.
The US Embassy air quality data discontinuation creates a significant gap in reliable air quality insights, particularly in these regions where alternative data is scarce. For years, this air quality data acted as a lifeline for communities without official monitoring – helping researchers track pollution, advocates push for change, and individuals protect their health.
However, this loss doesn’t have to be permanent. We’re donating 30 free air quality monitors to locations where data sharing from US Embassy monitoring stations has been discontinued. Our monitors are open-source, and the data can be easily shared with OpenAQ Inc.
If you are living in one of the affected cities, and are interested in hosting an AirGradient Open Air outdoor air quality monitor (that we will provide free of charge), please fill in below form:
Filling the Gap: Volunteers Needed to Host AirGradient Monitors