Tests of air quality on flights produces mixed results

Attention frequent flyers: the American Society of Heating Refrigerating and Air-Conditioning Engineers has announced the results of a preliminary investigation into the quality of air and conditions onboard commercial flights.
The pilot study of 400 passengers and flight crews used instruments to measure the cabin air quality and issued questionnaires to find out the human response. The study is to prepare and test tools for a much larger study of commercial aircraft that will be launched next spring.
The researchers found overall that the cabin air quality was “adequate.” They recorded elevated levels of carbon dioxide on all flights, especially during boarding and deplaning, though levels were well within guidelines. Ozone was found to be higher in the cabin during cruise conditions than during boarding or deplaning, and on one flight it reached levels that were of concern. Carbon monoxide and fine particulate matter were well within acceptable levels.
In regard to the passenger health and comfort, the results showed:
44% experienced pressure and pain in their ears during the flight;
22% experienced a dry or sore throat;
31% had dry eyes;
20% said the cabin was loud, and 3% said it was uncomfortably loud.