The designed operating cabin altitude for new aircraft is falling and this is expected to reduce any remaining physiological problems. Both the Boeing 787 Dreamliner and the Airbus A350 XWB airliners have made such modifications for increased passenger comfort. The 787's internal cabin pressure is the equivalent of altitude resulting in a higher pressure than for the altitude of older conventional aircraft; according to a joint study performed by Boeing and Oklahoma State University, such a level significantly improves comfort levels. Airbus has stated that the A350 XWB provides for a typical cabin altitude at or below , along with a cabin atmosphere of 20% humidity and an airflow management system that adapts cabin airflow to passenger load with draught-free air circulation. The adoption of composite fuselages eliminates the threat posed by metal fatigue that would have been exacerbated by the higher cabin pressures being adopted by modern airliners, it also eliminates the risk of corrosion from the use of greater humidity levels.