Odours in and around buildings

1 Defining odour
2 Assessing
3 Types of odours
4 Addressing household odours
5 Related articles on Designing Buildings
6 External links

[edit] Defining odour

In general an odour might be defined as any smell, particularly a stronger or more readily distinguished one, and is often used to describe an unpleasant smell but it can also be neutral. Contrary to this the term scent typically describes a characteristic or particular smell that is often, but not always, agreeable or pleasant.

Smells, scents and odours are part of everyday life some can act as a warning sign highlighting other issues such as damp, poor ventilation or worse still mould growth. Understanding and controlling the types of odours that are common in residential spaces is essential for improving indoor air quality, and more generally indoor environmental quality and in turn the health, and wellbeing of occupants.

The Scottish Environment Protection Agency (SEPA) "Odour guidance" published in January 2025 definition reads:

"Odour is perceived by our brains in response to chemicals present in the air we breathe. Odour is one of the effects that those chemicals have on us. Humans have a sensitive sense of smell and can detect odour even when chemicals are present in very low concentrations.

The subject of odour is a highly complex one and the response of an individual to odour exposure is subjective: their reaction will depend on issues such as how strong it is, what it smells like, how often and when it occurs and in what context."

Odours are an unavoidable part of everyday life in homes. They can signal comfort, the smell of fresh bread or clean laundry — but also highlight problems, from dampness to poor ventilation. Understanding the types of odours common in residential spaces is essential for improving indoor air quality, health, and wellbeing."

[edit] Assessing

"The following characteristics are relevant in the assessment of odours:

An odour can arise from a single substance or from a combination of substances.
In combination with other substances, the characteristic odour of a single substance can be modified so as to be unrecognisable.
Odour changes as the mixture becomes diluted. Individual components may fall below their odour threshold.
Odours from a substance or mixture of substances can be pleasant when dilute but offensive when concentrated.
Odours that are pleasant or acceptable to one person can be offensive and unacceptable to another and individuals can have different sensitivities to odour.

[edit] Types of odours

Odours can be stimuli for memory and emotion, they are closely tied to the brain’s limbic system, which governs memory and emotion. Herz and Schooler (2002, Memory & Cognition) found that odour-evoked memories are often more emotional and vivid than those triggered by other sensory cues. Research in sociology and anthropology has shown that perceptions of odour are culturally shaped (Classen et al., 1994, Aroma: The Cultural History of Smell). What is considered comforting in one household may be irritating in another.

Odours can be early warning signs of poor indoor air quality (IAQ) and indoor environmental quality (IEQ), the World Health Organisation (2010) notes that musty smells are strongly associated with dampness and mould, which in turn are linked to increased risk of respiratory problems. While odours themselves are often harmless, prolonged exposure to their sources, such as mould or chemical off-gassing, can affect health. A review by Schripp et al. (2014, Indoor Air) highlights the link between chemical odours and reported symptoms like headaches, eye irritation, and fatigue.

Researchers and indoor air specialists often classify odours into different categories based on their source and chemical composition, here are some suggested categories of different odours, but there are other methods of categorisation.

[edit] Biological odours

Originating from people, pets, plants, and microorganisms, such as sweat, pet dander (skin alergens), mould and mildew, bacteria from drains or garbage. Such Microbial volatile organic compounds (mVOCs) released by mould and fungi have been identified as key contributors to “musty” odours in damp buildings (Korpi et al., 2009, Indoor Air).

[edit] Combustion-related odours

Produced by cooking, heating, smoking, and burning candles or incense, such as frying oil, tobacco smoke, soot, wood-burning stoves. Cooking is one of the most significant indoor sources of odours and pollutants. A study by Zhang et al. (2010, Atmospheric Environment) found that frying and grilling release aldehydes, ketones, and fine particles that adhere to surfaces and fabrics, prolonging odour persistence.

[edit] Chemical and synthetic odours

These may be emitted from building materials, cleaning products, paints, solvents, and air fresheners such as volatile organic compounds (VOCs) from new paint, disinfectants, plastics, adhesives etc. Exposure to VOCs indoors can affect comfort and health. Weschler (2009, Atmospheric Environment) highlighted how chemical emissions from common household products interact with ozone indoors, generating secondary pollutants that intensify odours.

[edit] Environmental transfer odours

These types of odour describe external smells that might enter a home through ventilation, windows, or shared walls such as traffic fumes, industrial emissions, cooking smells from neighbours etc. Studies on urban housing, such as McGill et al. (2015, Building and Environment), show how poorly designed ventilation systems in multi-family housing allow odour transfer between units, impacting occupant satisfaction.

[edit] Pleasant and comfort-associated odours

Often described as scents but also as odours are not negative but positive and can contribute to the character of a home such as fresh laundry, flowers, scented candles, baking etc. Positive odours have been linked to wellbeing, with research in environmental psychology (Herz, 2004, Chemical Senses) demonstrating how pleasant household odours can evoke positive memories, reduce stress, and enhance perceptions of domestic comfort.

[edit] Addressing household odours

Understanding the source is the first step in managing odours, and improving ventilation helps to dilute and remove airborne smells. But identifying and addressing moisture problems that can be rectified to prevent mould is key. Increasingly there are low-VOC products available for cleaning and decorating, which should be specified and used as alternatives. Certain materials be used which can act to partly absorb or neutralise persistent smells, such as baking soda and activated charcoal. Odours in the home are complex, and shaped by biology, chemistry, culture, and perception. By recognising the different categories and learning from research into residential odours, households can take steps not only to reduce unpleasant smells but also to create a healthier, more pleasant indoor environment.