Summary — Acute vs Chronic Risk (professor on public understanding of risk) 🎓⚖️

Key concepts

• Acute risks: sudden events that can kill you immediately (e.g., falling down stairs, parachute failures).
  • Unit: micromort = 1 in 1,000,000 chance of death (useful for single-event risk comparisons). 🎯
• Chronic risks: repeated/habitual exposures that shorten life expectancy over time (e.g., smoking, diet, alcohol).
  • Unit: microlife = 0.5 hours of life expectancy lost/gained per day habit; a million microlives ≈ a typical adult lifetime (57 years). ⏳

Acute-risk examples (≈ micromorts)

• Everyday non-natural death risk (England & Wales): ~1 micromort per person per day.
• Travel / activity examples (rough averages):
  • Drive from Cambridge to Liverpool ≈ 1 micromort
  • Walk ~15 miles ≈ 1 micromort
  • Cycle ~20 miles (Cambridge less) ≈ 1 micromort
  • 6 miles on a motorbike ≈ 1 micromort
• Medical procedures:
  • Emergency general anaesthetic ≈ 10 micromorts
  • Routine anaesthetic ≈ 5 micromorts
• Leisure / extreme sports:
  • Scuba diving ≈ 5 micromorts
  • Hang-gliding ≈ 8 micromorts
  • Marathon ≈ 7 micromorts
  • Skydiving (US avg) ≈ 7 micromorts per jump (higher for advanced maneuvers)
  • BASE jumping ≈ hundreds of micromorts (very high)
  • Summit above 8,000 m (Everest-type): ~1 in 25 death risk ≈ 40,000 micromorts (comparable to WWII bomber missions)

Chronic-risk examples (≈ microlives)

• Interpretation: habitual daily exposures translate into minutes/hours lost or gained over lifetime.
• Approximate conversions used by speaker:
  • 1 daily portion of red meat (size of phone/burger) → +13% annual death risk → ≈ 1 year of life lost over lifetime → ≈ 0.5 hour (30 minutes) lost per day habit → 1 microlife.
  • 1 alcoholic drink/day (first drink) ≈ small average benefit (~+5 minutes/day); further drinks become harmful; ~6 units/day ≈ 30 minutes lost.
  • Two cigarettes ≈ 0.5 hour (30 minutes) lost (so 20 cigarettes/day ≈ ~5 hours/day effect measured as accelerated aging).
  • Being 5 kg overweight daily ≈ 0.5 hour lost.
  • Taking a statin (where indicated) ≈ 0.5 hour gained (example: could “cancel” a burger).
  • Five portions fruit & veg/day ≈ ~1 hour gained (compared to none).
  • Exercise: first 20 minutes of moderate daily exercise ≈ ~1 hour gained; next 20 minutes ≈ ~20 minutes gained (diminishing returns; benefits highly nonlinear).

Important caveats & messages ✅❗

• Micromorts and microlives are population-average metaphors for comparing risks — they do not precisely predict an individual’s outcome.
• Risks reported in media are often misleading or poorly contextualized (e.g., % increases sound big but may translate to small lifetime changes).
• Two useful metaphors:
  • Acute events = single micromort comparisons (one-off chance).
  • Chronic exposures = “accelerated aging” measured in microlives (speed toward death; living faster vs slower).
• Practical takeaway: framing risks as micromorts/microlives helps compare activities, choices, and trade-offs more intuitively.

Memorable analogies & lines 📝

• Micromort = flipping heads ~20 times in a row.
• Eating a burger daily ≈ half an hour of life expectancy lost (one microlife).
• Smoking 20 cigarettes/day ≈ ~5 hours/day “accelerated aging” effect.
• First 20 minutes of daily brisk exercise yields the biggest per-minute benefit.