Altistumisjakso

Altistumisjakso, or exposure period, is the time interval during which an individual is exposed to a chemical, physical, or biological agent in an environment. It is a fundamental concept in exposure science, toxicology, and occupational hygiene, used to characterize how long a person remains subjected to a hazard and how that duration contributes to the total internal dose and potential health effects.

It can be acute or chronic. Acute exposure denotes a short duration, typically hours or less, while chronic exposure involves repeated or continuous exposures over extended periods, from days to years.

Measurement and interpretation. The duration is often analyzed together with concentration to estimate dose. Common metrics include the time-weighted average (TWA) over a work shift or a longer assessment interval, as well as peak exposure for brief high concentrations. Regulators may set permissible exposure limits for defined periods, such as an 8-hour TWA or a 15-minute short-term exposure limit. Cumulative exposure, sometimes approximated as concentration multiplied by duration, informs risk characterization.

Applications and context. Altistumisjakso is used in occupational safety, environmental health, and regulatory risk assessment to plan control measures, monitor workplace conditions, and estimate potential health outcomes. Short exposure periods may be more relevant for acute effects, while long exposure durations are linked to chronic health risks.

Etymology and usage. The term derives from Finnish altistus (exposure) and jakso (period). In international literature the equivalent English term is exposure duration or exposure period.