Is a device used to perform odour measurements on active sources such as biofilters. It essentially is composed of a conical or pyramidal shape that encloses an area of the source. The centre of the enclosure has a cylindrical chimney for sampling and exhaust. According to the VDI3880, the ground area of the hood is to be at least 1m2 and with a chimney length that is at least six times its diameter.
A good practice when sampling solid surfaces is to seal the bottom of the sampling hood against the solid. If possible push the sampling hood into the surface or create an apron around the hood if possible. This will prevent dilution of the sample leading to reduce odour concentration measurement.