Key words: Odor microclimate, odor, olfactomery, perception threshold, detection threshold, deodorization, intense ionization of air

ODOR MICROCLIMATE

Odorous substances are gaseous air components, perceived as odors. These are inorganic or organic substances mostly produced by humans or their activities. There are five basic types of oder:

• ​Eternal Odor (Human Odors)
• Aromatic odor (ripe fruit)
• Isovaleric odor (smoke from tobacco smoke and animal sweat)
• Dusty odor (dairy products)
• Narcotic odor (degrading proteins)

 
Odor is a parameter that is difficult to quantify physically or chemically. It is the ability of odorous substances (odereants) or mixtures of substances to activate the sense of smell and to create sensation.
 
Odorants are organic or inorganic substances produced by humans themselves and their activities. The dominant constituents of odorous substances in the interior of buildings are carbon dioxide and volatile organic compounds. They are released from building materials and building facilities.
 
Olfakometry is a method of objectively determining odorous substances in the air based on human olfactory senses.
 
The threshold of perception is the lowest odor concentration at which the odor air is distinguished from the sensorless air by 50% of the assessors based on the primary air perception of the test air.
 
The detection threshold is the lowest odor concentration at which air with odorous substances is distinguished from the sensorless air of 50% of the assessors based on the clearly recognized sensation of the odor in the test air.
 
Odorous substances enter the interior from the outside or they are generated in an indoor environment (anthropogenic activities released from building materials). Approximately 50-80% of the odors enter the building from outside air. These are combustion engine products, production processes, and combustion gases from heat plants. As a result of human activities, various odors such as cigarette smoke, odors of cosmetics, smell of garbage and detergents are emitted.

BIOLOGICAL EFFECTS OF ODORS

Odorous substances have to encounter the mucous membrane to cause olfactory sensation. Ocular cells then transmit electrochemical impulses to the olfactory center in the front of the brain. A part of the brain, which is involved in the stench, is placed over the nose and it creates emotions. This implies that odors affect mood creation.
 
The effects of the odorous substances can be divided into 4 groups:

• Refreshing or reassuring
• Positively encouraging
• Atrophied or possibly intoxicating
• Involuntary states of nervous upheaval and aggression

OPTIMIZATION OF ODOR MICROCLIMATE

The optimal odor climate can be provided by interfering with the source of the odor or by interfering with the field of transmission from the source to the exposed subject.

The most effective way to optimize is to reduce or completely eliminate the odor source, for example by using fast-drying colors (colors that, in contact with UV radiation, cause a very rapid transition of low molecular weight to high molecular weight compounds) or waste bins.

The optimization of the odor microclimate by interfering with the transmission field can be achieved by limiting the spread of oders in the building, by sufficient ventilation, air filtration, deodorization or neutralization with ionized ozone. The principle of limiting the spread of odors in the building consists in the distribution of vertical shafts into several parts or appropriate placement resources odors. The amount of fresh air is related to the odor concentrations in the indoor environment.

Filtration of odors is carried out using filters with activated carbon or charcoal, by washing with water, by air, by biological washing machine or by biological filter. Active or charcoal filters do not absorb almost any moisture and do not change the air condition. Their effectiveness depends on the time of gas contact with coal. For at least 80% efficiency, a layer of  active coal at least 25 mm thick is required and the flow rate through the filter should not exceed 3.0 m/s. Washing air with by water is especially effective for substances that are capable of binding to water, such as ammonia. The Biological washing machine works on the principle that odor gases are absorbed in scrubbing liquid with dispersed microorganisms. This filtration method is particularly suitable for heavily polluted gases. Biological filters comprise a natural filling - peat, in which the microorganisms are capable of degrading aromatic compounds, such as hydrocarbons. A great advantage of these filters is their low operating costs.

Deodorization is based on the use of a different, stronger, but pleasant odor (fragrance) than the original odor.

The neutralization effect is based on ionized ozone, which is a strong oxidizer. Molecules of odorous substances are decomposed and converted into water vapor, carbon dioxide and other non-odorous substances. Consideration must be given to the concentration of ozone due to its toxicity.

The odors can also be eliminated by intensive ionization of air with high concentrations of negative aeroionics.

Houseplants are not only an adornment and a consumer of CO₂, but some species are also able to purify the air from benzene, carbon dioxide, nitrogen dioxide and formaldehyde.