Odour is a sensory response to the inhalation of chemicals. When the sensors in your nose come into contact with an odorous chemical they send a signal to your brain which interprets the signal as an odour. The human sense of smell is very sensitive to a wide range of odorous chemicals.
Odours are caused by mixtures of chemical compounds.
They come from a wide range of sources such as:
- garden compost heaps
- car and bus exhausts
- mushroom farms
- pig farms.
Odours in the environment are mainly a nuisance as they affect enjoyment of the outdoors. In more serious cases they can lead to sickness (eg, nausea and headaches). People’s response to odour varies (eg, people who live and work in rural areas may not be affected by silage smells while urban dwellers may find them offensive).