Hi Tara, small source pollution (e.g., neighborhood drycleaners, etc) is from research by Jason Corburn, see his 2005 book Street Science. Pollution spikes in fenceline communities refers to Norco, LA and the Shell plant, work that was done by the Lousiana Bucket Brigade, and reported by Gwen Ottinger in her 2010 paper Buckets of Resistance, and others. If you need more info etc, google me at UCSB & email there.