Cosmic radiation on flights from Los Angeles (LAX) to London (LHR)
A flight from Los Angeles International Airport to London Heathrow Airport at 35,000 ft, about 9 h 56 min in the air, receives about 0.0434 mSv (43.4 µSv) of cosmic radiation: about 43% of a chest X-ray. That is the FAA's CARI-7 model run for this route with the solar conditions of August 2026.
Updated · solar conditions of August 2026
- Dose
- 43.4 µSv0.0434 mSv
- Time in the air
- 9 h 56 minestimated
- Dose rate
- 4.4 µSv/haverage, 35,000 ft
- Chest X‑rays
- 0.43at 0.1 mSv each
Key facts: LAX → LHR
| Dose, standard flight | 0.0434 mSv (43.4 µSv) |
|---|---|
| Time in the air | 9 h 56 min, estimated from distance and prevailing winds |
| Cruise altitude | 35,000 ft |
| Average dose rate | 4.4 µSv/h |
| Great-circle distance | 8,760 km (5,443 mi) |
| Furthest from the equator | 62.3°N |
| Solar conditions | August 2026 |
The standard flight is CARI-7, the FAA Civil Aerospace Medical Institute's model, run on the dev machine for this route: 35,000 ft, 9 h 56 min in the air (climb 25 min, cruise 554 min, descent 17 min), effective dose per ICRP Publication 103. How it's calculated.
How the sun changes the dose on LAX → LHR
The sun's 11-year cycle moves this number. With the same 9 h 56 min at 35,000 ft, the flight would have received 0.056 mSv in April 2020, when the sun was quiet and more galactic cosmic rays reached the atmosphere, and 0.0332 mSv in January 2026, near solar maximum: 69% more at the quiet end. In August 2026 it is 0.0434 mSv.
The numbers behind the chart
| Month | Dose | Dose |
|---|---|---|
| January 2016 | 48.4 µSv | 0.0484 mSv |
| April 2016 | 50 µSv | 0.05 mSv |
| July 2016 | 49.7 µSv | 0.0497 mSv |
| October 2016 | 51.7 µSv | 0.0517 mSv |
| January 2017 | 52.4 µSv | 0.0524 mSv |
| April 2017 | 53.9 µSv | 0.0539 mSv |
| July 2017 | 52.8 µSv | 0.0528 mSv |
| October 2017 | 52.2 µSv | 0.0522 mSv |
| January 2018 | 53.3 µSv | 0.0533 mSv |
| April 2018 | 54.9 µSv | 0.0549 mSv |
| July 2018 | 54.6 µSv | 0.0546 mSv |
| October 2018 | 55.9 µSv | 0.0559 mSv |
| January 2019 | 52.8 µSv | 0.0528 mSv |
| April 2019 | 55.7 µSv | 0.0557 mSv |
| July 2019 | 54.8 µSv | 0.0548 mSv |
| October 2019 | 55.7 µSv | 0.0557 mSv |
| January 2020 | 55.4 µSv | 0.0554 mSv |
| April 2020 | 56 µSv | 0.056 mSv |
| July 2020 | 55.5 µSv | 0.0555 mSv |
| October 2020 | 55.5 µSv | 0.0555 mSv |
| January 2021 | 53.3 µSv | 0.0533 mSv |
| April 2021 | 55.8 µSv | 0.0558 mSv |
| July 2021 | 54.2 µSv | 0.0542 mSv |
| October 2021 | 54.5 µSv | 0.0545 mSv |
| January 2022 | 53.1 µSv | 0.0531 mSv |
| April 2022 | 52.5 µSv | 0.0525 mSv |
| July 2022 | 47.5 µSv | 0.0475 mSv |
| October 2022 | 49.2 µSv | 0.0492 mSv |
| January 2023 | 44.3 µSv | 0.0443 mSv |
| April 2023 | 44.9 µSv | 0.0449 mSv |
| July 2023 | 42 µSv | 0.042 mSv |
| October 2023 | 42.3 µSv | 0.0423 mSv |
| January 2024 | 39.5 µSv | 0.0395 mSv |
| April 2024 | 40.8 µSv | 0.0408 mSv |
| July 2024 | 41.2 µSv | 0.0412 mSv |
| October 2024 | 35.4 µSv | 0.0354 mSv |
| January 2025 | 36.8 µSv | 0.0368 mSv |
| April 2025 | 36.9 µSv | 0.0369 mSv |
| July 2025 | 36.4 µSv | 0.0364 mSv |
| October 2025 | 37.5 µSv | 0.0375 mSv |
| January 2026 | 33.2 µSv | 0.0332 mSv |
| April 2026 | 38.2 µSv | 0.0382 mSv |
| July 2026 | 41.2 µSv | 0.0412 mSv |
| August 2026 | 43.4 µSv | 0.0434 mSv |
How cruise altitude changes the dose
Flown at 31,000 ft instead, the same flight would receive 0.0313 mSv, 28% less than at 35,000 ft; at 41,000 ft it would receive 0.0635 mSv, 46% more. Same route, same time in the air, same month: only the air overhead changes.
Try it: change the altitude and the month
Every combination is its own CARI-7 run for LAX → LHR, with the same 9 h 56 min in the air. It is still a standard flight, not yours: the app calculates your exact flight.
Every combination as a table (µSv)
| Altitude | Jan 2016 | Jan 2017 | Jan 2018 | Jan 2019 | Jan 2020 | Jan 2021 | Jan 2022 | Jan 2023 | Jan 2024 | Jan 2025 | Jan 2026 | Aug 2026 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 31,000 ft | 34.8 | 37.5 | 38.1 | 37.8 | 39.5 | 38.2 | 38 | 32 | 28.6 | 26.7 | 24.2 | 31.3 |
| 33,000 ft | 41.3 | 44.7 | 45.4 | 45 | 47.2 | 45.4 | 45.3 | 37.9 | 33.9 | 31.6 | 28.5 | 37.1 |
| 35,000 ft | 48.4 | 52.4 | 53.3 | 52.8 | 55.4 | 53.3 | 53.1 | 44.3 | 39.5 | 36.8 | 33.2 | 43.4 |
| 37,000 ft | 55.8 | 60.5 | 61.6 | 61 | 64 | 61.6 | 61.4 | 51 | 45.4 | 42.2 | 38 | 49.9 |
| 39,000 ft | 63.5 | 69 | 70.2 | 69.5 | 73.1 | 70.3 | 70 | 57.9 | 51.4 | 47.7 | 42.8 | 56.6 |
| 41,000 ft | 71.4 | 77.8 | 79.2 | 78.4 | 82.6 | 79.3 | 79 | 65 | 57.5 | 53.2 | 47.6 | 63.5 |
The return flight: LHR → LAX
LHR → LAX receives 0.0487 mSv at 35,000 ft, 12% more than LAX → LHR, over about 11 h 6 min in the air against 9 h 56 min. The return takes 1 h 10 min longer: its track runs against the prevailing westerly winds at cruise altitude. Cosmic radiation builds up with every minute aloft, so the longer direction collects more of it along the same path.
What 43.4 µSv compares with
| Compared with | Its dose | This flight is |
|---|---|---|
| Chest X-Ray | 0.1 mSv | about 43% of a chest X-ray |
| Dental X-Ray | 0.005 mSv | about 8.7 dental X-rays |
| Background Radiation (Daily) | 0.008 mSv | about 5.4 days of natural background radiation |
| Mammogram | 0.4 mSv | about a tenth of a mammogram |
| Head CT Scan | 2 mSv | about 2% of a head CT scan |
| Eating a Banana | 0.0001 mSv | about 434 bananas |
The comparison values are the ones the FlightDose app uses.
Why your flight will differ
- Altitude. Flown at 31,000 ft instead, the same flight would receive 0.0313 mSv, 28% less than at 35,000 ft; at 41,000 ft it would receive 0.0635 mSv, 46% more. Same route, same time in the air, same month: only the air overhead changes.
- Time in the air. Every extra 30 minutes on this route adds about 2.2 µSv. Headwinds, holding and routing change it by tens of minutes on a long flight.
- The month. The sun's 11-year cycle swings this route's dose by about 69% between quiet and active years.
- The track. Airlines fly tracks that bend with the jet stream, not the exact great circle; a track further from the equator collects more.
- Solar storms. A rare solar radiation storm can add to the dose for hours; CARI-7's monthly figures don't include one.
FlightDose calculates your exact flight.
Your date, your altitude, your time in the air, with live space weather, and a running total against the limits that matter to you.