Europe’s airports have been troubled by Icelandic volcanic ash for the past three weeks. While a growing number of airports are reopening and accepting passengers, many are boarding flights hesitantly, concerned about the potential health problems caused by ash and dust caught in air conditioning systems.
Allergies, reactions, and ill-effects caused by airplane air conditioning are relatively common, with many passengers experiencing dry breathing passages or a common cold during their holiday. Most aircraft air conditioners are fitted with large filtration systems, ensuring the ash and grit won’t pass through into the cabin, but a number of passengers are still concerned. 
The potential risks don’t seem to be limited to those inside the cabin, either. Pilots are concerned about emergency landings which could be caused by the ash. As grit and dust enters the plane’s air conditioning system – a system also responsible for regulating cabin air pressure – pilots may be required to switch air conditioning off to ensure passengers are kept safe.
While relatively inconsequential for local flights, international flights and long-haul carriers may need to land in order to clear out the dust and carry out air conditioning maintenance. With many British air travellers still stranded overseas, news of health risks from airlines certainly aren’t coming as welcome news.