hajuyhdisteet

Hajuyhdisteet are a broad category of chemical substances that produce smell or odor. In environmental and industrial contexts, the term refers to volatile compounds that can be perceived by the human nose at low concentrations and contribute to the odor profile of air, water, or products. They are often discussed together with volatile organic compounds (VOCs), though regulatory definitions may vary by jurisdiction.

Common hajuyhdisteet include sulfur-containing compounds (such as mercaptans and hydrogen sulfide), amines (for example trimethylamine), short-chain fatty acids, aldehydes, ketones, esters, terpenes, and various phenols. Many odorants have very low odor thresholds, so trace amounts can dominate perception even when concentrations are small. Their odors range from foul to pleasant, influencing consumer experience and environmental quality.

Sources come from natural processes (fermentation, decomposition, plant and animal emissions) and human activities (wastewater treatment, farming, food processing, industries using solvents, and waste handling). Odor profiles are often used to diagnose the source and to assess the environmental impact of a site.

Measurement relies on sensory methods and instrumental analysis. Dynamic olfactometry estimates odor concentration in OU (odor units); GC-Olfactometry couples chemical analysis with human detection to identify odor-active compounds. Instrumental techniques such as GC-MS help identify the chemical structures of individual hajuyhdisteet in a mixture.

Management aims to reduce nuisance and potential health impacts. Control methods include process changes, activated carbon adsorption, biofiltration, and thermal oxidation. Odor regulation typically sets emission limits or requires odor-control plans for facilities such as wastewater treatment plants, landfills, and food processing sites.