Odour: Environment and Public Health

What is an odour?

An odour is a characteristic of a material or chemical that one can smell.  Not all chemicals have an odour. Some odours are caused by a single chemical but many odours come from a mixture of chemicals. Apparently, the smell of coffee is made up of over 300 different odourous chemicals which combine to give the coffee smell.

Reactions to odours may vary from person to person.  Some odours are generally considered to be pleasant e.g. freshly baked bread or a popular perfume. However, some odours are usually perceived to be unpleasant such as waste matter and rotten food. The perception of offensive odour may have developed as a protective mechanism for humans to avoid eating such material.

Is there a health risk?

Odour in itself may not be dangerous to health. However, the material from which it comes may or may not have health risks.  So, an assessment of health risk depends on the source of the odour.

Some chemicals with odour properties can have toxic effects on humans. The smell can be a warning to move away and so the odour can protect us. For most of the chemicals that can cause health problems, we can smell them before they are toxic to us. For some chemicals, odour may be the first indicator of a potentially serious incident. 

For a few chemicals, toxicity can occur before the odour is perceived - i.e. the level at which toxicity occurs is lower than the level at which odour occurs.

Assessment of health risk requires an understanding of the odour properties of chemicals. This allows authorities to protect the public in the most appropriate way.

What sort of health problems can occur?

Odour can have neurological effects on emotions and memory. Exposure to offensive odours can cause stress and/or reduced quality of life. The material that is the source of the odour may in itself have health effects depending on its toxicological properties. 

Ongoing exposure to offensive odours can exacerbate health risks.  The types of complaints to the Environmental Protection Agency (EPA) about effects associated with nuisance odours include symptoms such as: Vomiting; Headaches; Nausea; and feelings of Stress, Anxiety and Frustration.

Other effects complained of include: Having to leave home and stay with family/friends or incur the expense of a hotel; Unable to open windows during summer time or use the garden; Children unable to sleep due to odour in bedrooms; and an additional discomfort for infirm elderly people.

Odour nuisance is considered to be pollution.

How is the public protected?

The types of chemicals that can cause health problems for the public are generally regulated. For example, the Environmental Protection Agency (EPA) regulates industries by licensing or permitting.

How can I find out more about assessing offensive odours?

The EPA has a particular role in the assessment of nuisance odours from IPPC or waste facilities in Ireland and has produced an Air Guidance Note 5 (AG5) Odour Impact Assessment Guidance for EPA Licensed Sites to assist with the assessment of odours at regular intervals, in response to complaints and in various weather conditions.