According to the information provided by Sohu. The work of odor sampler needs to sample and analyze the odor in the air, so the personnel who undertake this important task must be trained and assessed by sniffers.

After professional training, odor samplers need to distinguish five kinds of single gases: floral, sweaty, sweet crispy, ripe fruit and dung. They can only take up their posts after passing the qualification examination (written test+odor test) and obtaining the qualification certificate of sniffer or judge. The qualification certificate needs to be re-examined every three years.