Radiation Exposure Log Without a Dosimeter

Radiation damage is cumulative — total dose received determines symptom severity and long-term health outcomes. Doses below 0.5 Gy may show no immediate symptoms; 0.5–2 Gy causes radiation sickness; above 6 Gy is typically fatal. Without a dosimeter, you must estimate exposure from location, distance, shelter, and time to build a record for medical personnel later.

Do not wait for perfect measurements. A rough paper log is better than no record at all.

Radiation exposure halves with every doubling of distance from the source (inverse square law). If you are 100 meters from fallout, you receive 1 unit of exposure; at 200 meters, 0.25 units; at 400 meters, 0.0625 units. Sheltering indoors reduces exposure by 10–1000× depending on material (wood ~10×, concrete ~100×, ground basement ~1000×). Record distance estimates and shelter type in your log.

These are rough estimates. Actual exposure varies with fallout particle size and wind patterns.

Radioactive fallout halves in intensity every 7 hours after detonation (the '7-10 rule'). At 1 hour post-detonation, note the exposure level; 7 hours later it is half; 14 hours later it is one-quarter. Staying sheltered for 24 hours reduces exposure by ~90%; 48 hours reduces it by ~99%. Log shelter entry/exit times so medical teams can estimate total dose received.

Symptom onset timing roughly indicates dose: nausea/vomiting within 2 hours = high dose (>2 Gy); within 2–6 hours = moderate dose (1–2 Gy); after 6 hours or absent = lower dose (<1 Gy). Note the exact time each person reports symptoms (nausea, vomiting, diarrhea, headache, skin redness, hair loss) and when symptoms started. This timeline is diagnostic for medical teams assessing cumulative exposure.

Nausea may also indicate stress or dehydration. Medical personnel will interpret symptom patterns, not individual reports.

For each person, record: Name & Age, Time of Exposure Start, Location & Distance from Fallout, Shelter Type & Times In/Out, Estimated Hours Exposed, Observed Symptoms & Times, Medications or Injuries. Use a small notebook or printed form. Include date, time zone, and initials of the person recording. Keep the log dry and safe—medical teams will need it to guide treatment decisions.

Prioritize shelter for children and pregnant women first — they are more radiosensitive. When you reach a medical facility, give all logs to the receiving doctor. Explain when each person was exposed, where, and what symptoms developed. Medical personnel can estimate total dose from the timeline and symptoms, even without a dosimeter. Accurate logs improve treatment decisions and long-term health monitoring.

If medical personnel are unavailable, keep logs with the person at all times for handoff when care becomes available.