Can’t keep smoke out

Half the block gets stunk up to high heaven every evening after dark. It seeps inside and even 2 HEPA air purifiers are no match! I resorted to spray-foaming around all vents and light fixtures in the attic, but it still seeps in. I have been walking up and down the street every evening trying to determine which neighbor is doing this, but only end up choking and coughing, and my clothes and hair and skin stinking as well. This is a dense single family home residential area and they are definitely not burning just wood.