microlives

Microlives are small units used in public health to express the effect of a given behavior, exposure, or intervention on an individual’s life expectancy in terms of minutes or fractions thereof. The idea translates probabilistic mortality risk into an intuitive timespan, so that people can compare the potential impact of different choices, such as smoking, physical activity, diet, alcohol consumption, or exposure to air pollution.

Microlives are derived from epidemiological data and life-table modeling. Relative risks associated with a factor are applied to baseline mortality, yielding an estimated change in expected lifespan for a person of a given age and sex. Because these estimates rest on population-level data and model assumptions, they are approximate and should be interpreted with caution. They are most useful for broad comparisons at the population level and for simple risk communications rather than precise predictions for individuals.

Common uses include online risk calculators and health communication materials that seek to convey the magnitude of risk in an everyday metric (minutes of life). Examples of factors often presented as microlives include smoking, regular physical activity, high-fat diet, excessive alcohol, and air pollution exposure; less consistently, sleep quality, stress, or sun exposure.

Limitations include variability by demographic group, interactions among factors, latency periods, and the fact that microlives do not capture non-fatal health outcomes or the quality of life.

History: The term gained traction in public health circles in the late 2000s and has since circulated in risk communication research and popular media.