PDFWAC 246-215-06515
Methods—Cleaning ventilation systems, nuisance and discharge prohibition (FDA Food Code 6-501.14).
(1) Intake and exhaust air ducts must be cleaned and filters changed so that they are not a source of contamination by dust, dirt, and other materials.
(2) If vented to the outside, ventilation systems may not create a public health hazard or nuisance or unlawful discharge.