LA is in the San Fernando Valley.
Knock the valley down, and the pollution goes away.
1. You may be missing the point here.
2. "The San Fernando Valley is located in
Los Angeles County,
California. It includes the cities of
Burbank,
Glendale,
San Fernando,
Hidden Hills, and
Calabasas, as well as many neighborhoods within the
city of Los Angeles, such as Northridge, Arleta, Canoga Park, Chatsworth, Encino, Granada Hills, Lake View Terrace, Mission Hills, North Hollywood, North Hills, Pacoima, Panorama City, Porter Ranch, Reseda, Sherman Oaks, Studio City, Sun Valley, Sunland, Sylmar, Tarzana, Toluca Lake, Tujunga, Van Nuys, Valley Village, West Hills, Winnetka, and Woodland Hills.
https://libguides.csun.edu/la-san-fernando-valley/sfv
Los Angeles ... 75 towns in search of a city.