Newcastle Urban Observatory
I’ve just come across the Newcastle Urban Observatory. It is a data portal that collects feeds from various sensors across the city, including things like traffic, weather and noise levels, temperature, and air quality (NO, CO, and NO2).
You can also interrogate individual sensors and look at how the different levels have been changing over time (see below). It looks like it could be a really valuable resource, especially as the number of sensors reporting this kind of information increase.