Polar geoengineering could expose flights to sulphuric acid
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- Alan Robock at Rutgers University led a study modelling how polar geoengineering could expose passengers on certain commercial flights to hazardous sulphuric acid concentrations in their aircraft cabins.
- Researchers modeled using upgraded Boeing 777s to deposit sun-reflecting compounds near the poles, where the stratosphere dips to 7km — far lower than the ~20km altitude equatorial spraying would require from nonexistent aircraft.
- Simulations modeled injecting 6 million tonnes of sulphur dioxide near the North Pole (March-June) and 6 million tonnes near the South Pole (September-December), totaling 12 million tonnes — enough to cool the globe 0.6 to 1.0°C.
- Cabin concentrations could span roughly 7 micrograms per cubic metre (below levels in many major cities) to over 50 micrograms per cubic metre, which the EU defines as hazardous.
- Risks include respiratory irritation, asthma attacks, and increased stroke risk, with pilots and flight attendants facing the highest cumulative exposure on routine polar flight paths.
- Wake Smith of Harvard University called the deployment timeline 'many decades away, if it ever happens,' noting airlines would have time to upgrade air filters to handle the sulphur loads.
- Daniele Visioni at Cornell University called the results 'interesting preliminary' but 'definitely not anything that would be a dealbreaker,' adding 'the risks clearly lie elsewhere.'
Why it matters: Pilots and flight attendants on routine polar flights would absorb the highest cumulative exposure if sulphur-based geoengineering were ever deployed at scale. Modelled peak cabin concentrations exceed the EU's 50-microgram hazardous threshold, adding a new public-health layer to a climate intervention researchers describe as decades away at earliest.
