what is odour?
An odour is perceived when chemicals in gas form stimulate the human olfactory system (your nose). The human nose has hundreds of receptors, each coded by unique DNA to detect different odours, and therefore accounting for why different people have different sensitivity and reactions to smell. Scientists also suggest that the sense of smell is intimately associated with the formation of memories. Reactions to odours can be very subjective. A smell may be pleasant to one person and unpleasant to someone else. This can make the objective assessment of odour difficult to achieve.
what is offensive odour?
People experience odours differently, so only the individual being affected can claim that the odour is offensive (affecting their amenity or aesthetic enjoyment). EPA can, therefore, only trigger an investigation into an odour complaint when odour is reported by a community member as being offensive.
Offensive odour affects the general life, health and wellbeing of an individual as a result of the intensity, character, frequency and duration of the odour. The basis for acting against offensive odours may vary according to where the odour occurs. As an example, the normal agricultural odours present in a rural environment may not be considered offensive in an
open paddock, but may be considered offensive in a residential area. In order for EPA to take action on offensive odour, the odour must be verified and sourced by an environment protection officer who is accredited to assess odour and take statements from reporters. Human noses are the most sensitive instrument available to measure odour.
where do odours come from?
Odour can come from many different sources, but EPA becomes involved when offensive odour is generated from industrial and commercial premises. Odour from domestic sources and some smaller commercial premises, such as shops and restaurants, should be referred to local council officers. The strength and intensity of an odour depends heavily on the prevailing weather conditions and will vary with small changes in wind speed and direction. At night or during colder months, atmospheric mixing is reduced and air close to the earth is trapped by a layer of colder air. In these conditions odours travel further and do not readily disperse.
During hot weather sites that generate odour, such as abattoirs or composters, may produce more odour due to the faster decay
planning to prevent odour
Most of the odour incidents reported to EPA are due to existing premises that have not been appropriately designed or located, or where housing has since been built up to an existing industrial site.
EPA publication AQ 2/86, Recommended buffer distances for industrial residual air emissions, gives guidelines for planning authorities to consider in the planning process. Councils also assess compliance with existing planning permits and can take action to address amenity and health issues.
what can companies do to reduce odour?
Many industries are progressively improving operations to reduce emissions. EPA expects continuous improvement to contemporary industry standards. Installation of air emission control equipment, such as biofilters and scrubbers, and reduction of stockpiles can reduce potential odour sources. Some companies undertake odour audits to identify the main odour sources, or odour modelling to test the likely dispersion of odour from their premises. Following such assessments, they will then determine the best means for control. EPA works with such sites to achieve best-practice environmental performance.