I'm not sure which map you're looking at. Irwindale is located in LA county, one of the most populated areas of the US. Obviously if the smell didn't go very far it wouldn't be much of a problem.
The AQMD is one of the shadiest governmental agencies there is - apparently their main function is to demand enough shakedown money from SoCal businesses so they leave town.
See http://www.latimes.com/local/la-me-1110-sriracha-20131110,0,..., also posted in another comment on this thread.