1Effective measures shall be taken to prevent infestation by and harborage of 13vermin. All migrant and seasonal farmworker housing units shall be free of all vermin and maintained in a vermin free and vermin proof condition. All outside openings shall be effectively sealed or screened with a 16 mesh screen or equivalent in order to prevent entry of insects, rodents, or other vermin. If evidence shows that an infestation of vermin is found in the housing units, the owner or operator of the housing unit will be required to hire a licensed or certified exterminator to exterminate the vermin found in the housing unit. The owner or operator shall inform the migrant or seasonal farmworkers by posting a notice in the camp or housing unit to which it applies of any indoor application of pesticides prior to the application. When a licensed or certified exterminator applies pesticides in the home unit, the owner or operator shall obtain from the licensed or certified exterminator information about the potential risks and safety precautions that must be taken. The owner or operator shall share the information with the farmworkers and other household occupants. The owner or operator shall provide proof to the county health department official at the next inspection that the housing unit was exterminated by a certified exterminator, with a receipt for the extermination service rendered. Failure by the owner or operator to provide proof to the department that measures taken to control vermin in the housing unit are department approved, shall constitute a violation of this chapter.