A system which reduces the transmission of noxious fumes into the surrounding air during the application of a heated liquid roofing product on a roof. A mobile tanker or kettle contains a supply of the heated liquid. The air space within the tanker or vessel above the liquid product communicates with a mobile filtration unit by a first duct. A rooftop carrier for the liquid product has a fume collection hood which communicates with the filtration unit by a second duct. A blower in the filtration unit creates negative pressure which draws the noxious fumes from the tanker or vessel and carrier through the ducts and into and through the filtration unit. The filtration unit has a series of airtight chambers mounted on a mobile truck bed, each containing a different type of filtering medium to remove various components of the noxious fumes as the fumes move through the filtration unit. A burner unit having an open flame incinerates certain oils and gases and vapors within the fumes, after which the super-heated fumes are discharged into an air plenum into which cooler outside ambient air is introduced to cool the fumes prior to the fumes entering the filtration unit.