We rate highly cities with strong air quality laws and consistently low (good) air quality index.
What would it look like to measure the "air quality" of a network? This would be a step above a SPAM filter, as rather than looking at "junk" we would anticipate those parts of language that are operative, or operative in relation to a particular subject.
The term gaslighting comes from the 1938 play Angel Street, which Alfred Hitchock later adapted into the film Gaslight, in which a man tries to convince his wife that she is going insane so he can steal from her. When he turns on the lights in the attic to search for her jewelry collection, and the gas lights dim downstairs, he tells her it’s all in her imagination. Gradually she begins to question her own memories and perceptions.
Air quality laws govern the emission of air pollutants into the atmosphere. wikipedia 
An air quality index communicates to the public how polluted the air currently is or how polluted it is forecast to become. wikipedia