FAA - Federal Aviation Administration

01/07/2025 | Press release | Distributed by Public on 01/07/2025 15:04

Cabin Air Quality

Cabin Air Quality

Tuesday, January 7, 2025

The FAA is committed to protecting the safety and health of passengers and cabin crews on our nation's airlines. The agency has strict cabin air standards, and studies have shown cabin air is as good as or better than the air found in offices and homes. In rare instances, mechanical issues such as failures of an engine oil seal or recirculation fan bearings can cause fumes to enter the cabin. Airlines are required to report these incidents to the FAA. The FAA investigates the causes and makes sure they're fixed before the aircraft returns to service.

Background

  • The FAA requires airplane manufacturers to show that the crew and passenger compartment air is free from harmful or hazardous concentrations of smoke, vapor, or toxic or noxious fumes during normal operating conditions and in the event of any probable failure conditions.
  • FAA regulations require airliners' ventilation systems to supply clean air to both passengers and crew members. Airplanes must be designed to provide the equivalent of 0.55 pounds of fresh air per minute per occupant, a ventilation rate that is consistent with other public environments.
  • Most of today's large transport category airplane ventilation systems provide a mix of fresh air/engine bleed air and recirculated airflow. The mix is approximately 50 percent but can vary depending upon the flight altitude and power settings.
  • Most U.S. commercial airplanes use High Efficiency Particulate Air (HEPA) filters in the recirculated airflow, which remove 99.97 percent of particulate material.
  • While the FAA does not have a definition for a "fume event," airlines are required to file Service Difficulty Reports (SDRs) when smoke, vapor or noxious odors enter the cockpit or passenger cabin.
  • The FAA, airplane manufacturers, and air carriers maintain cabin air quality by defining appropriate design standards, designing the environmental control systems to meet those standards, and conducting proper maintenance, respectively.

Recent Research Initiatives and Actions

Section 323 of the FAA Reauthorization Act of 2024 directed the FAA to engage the National Academies of Sciences, Engineering, and Medicine (NASEM) to conduct a one-year study on the health and safety effects of minimum and maximum aircraft cabin temperatures on passengers and crew.

  • The FAA has engaged the NASEM and has met to discuss and plan this research effort.
  • The FAA will finalize an agreement and funding for the project after defining the scope.

Section 326 of the FAA Reauthorization Act of 2018 required the FAA to commission a cabin bleed-air quality study by the Intermodal Transportation Environment-Airliner Cabin Environment Research (RITE/ACER) Center of Excellence (COE). The Act required the study to include technologies to prevent fume events and warn of bleed air contamination and assess occupant health effects from exposure to bleed air contaminants.

  • The FAA commissioned the study in December 2018 and in December 2020 FAA submitted an interim report to Congress that described its plan to address Section 326.
  • The FAA conducted testing at Kentucky State University (KSU) in 2022 and the FAA William J. Hughes Technical Center (FAA Technical Center) in 2023.
    • The testing at KSU involved injecting known quantities of engine oil, hydraulic fluid, and deicing fluid into a test engine.
    • The testing at the FAA Technical Center involved injecting oil and hydraulic fluid into an engine and auxiliary power unit bleed air on an FAA-owned Boeing Model 747 aircraft.
    • Measurements were made with multiple sensors and chemical samples were also obtained and sent to laboratories for analysis.
    • The FAA Civil Aerospace Medical Institute, in conjunction with FAA and U.S. Navy chemists and U.S. Navy toxicologists, performed the health-effects assessment in collaboration with two U.S. Navy Commands - the Naval Air Warfare Center Aircraft Division (NAWCAD) for independent chemical sampling and analysis and the Naval Medical Research Unit Dayton (NAMRU) for toxicological analysis and interpretation.
    • The first of three reports on this research, DOT/FAA/TC-21/45, Aircraft Air Quality and Bleed Air Contamination Detection, is available here(link is external).
    • The FAA anticipates the other two reports will be released by the end of 2024. They will be available here.
    • A separate, independent Navy report and datasets are available here.

The FAA sponsored research to determine if current commercial technology was available that could detect smoke/odor/fumes from internal sources such as failures of environmental control system recirculation fans, circuits, and electrical cables). The final report is available here.

The FAA follows European Union Aviation Safety Agency (EASA) sponsored research(link is external) on cabin air quality and safety.

The FAA participates in committees that are developing industry standards for addressing the cabin environment, which include:

  • Bleed Air Committee (E-31B) - Development of Transient Measurement Methods for Aircraft Propulsion Engine and Auxiliary Power Unit Generated Contaminants in Bleed Air.
  • Cabin Air Measurement Committee (AC-9M) - Development of Cabin Air Measurements for installed sensors to provide airline operators maintenance with information to improve troubleshooting procedures on reported fume events.

Historical Research and Initiatives

The FAA created and sponsored the RITE/ACER COE from 2004 through 2015. Research conducted is available for public review on the FAA website. The research shows:

  • FAA air quality regulatory requirements reflect a general consensus of aircraft manufacturers that the minimum levels of CO (carbon monoxide) and CO2 (carbon dioxide) are good indicators of overall air quality.
  • The existing design standards have ensured an acceptable cabin environment during normal operations.
  • The environmental control systems used in commercial transport category airplanes, when properly operated and maintained, provide an environment that is equivalent to or better than that of other forms of commercial transport.

In response to provisions of the 2012 FAA Modernization and Reform Act, the FAA assessed cabin air quality. In December 2015, the FAA published a report called "Aircraft Cabin Bleed Air Contaminants: A Review," which describes the potential health-related risks of human exposure to bleed-air contaminants generated during fume events. The report found that the rate of cabin air quality events is less than 33 events per million aircraft departures.

The FAA continues to work with airplane manufacturers, air carriers, and research institutes to study the cabin air quality of in-service aircraft to ensure an acceptable cabin environment.

The FAA, EASA, and industry experts have sponsored or conducted studies that indicate the air quality of transport airplane cabins is on par with other forms of public transportation and with public buildings and homes.

Related Studies

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Final Report: Preliminary Cabin Air Quality Measurement Campaign (CAQ) EASA.2014.C15 and Preliminary Cabin Air Quality Measurement Campaign-CAQ II, EASA.2014.C15.SU01. (p. 130). Available at the following website: https://www.easa.europa.eu/en/document-library/research-reports/easarepresea20144(link is external)

Study of aldehydes, CO, and characterization of particles resulting from oil contamination of aircraft bleed air. [Doctoral dissertation, Kansas State University], K-State Research Exchange.

Aircraft cabin air sampling study, part 1 and part 2 of the final report. (Reference No. YE29016V). Institute of Environment and Health. Cranfield University.

The nature of particulates in aircraft bleed air resulting from oil contamination (Paper No. LV-17-C047). [Paper presentation]. ASHRAE Winter Conference, Las Vegas, NV, United States.

Experimental determination of the characteristics of lubricating oil contamination in bleed air. (Paper No. LV-17-C046). [Paper presentation]. ASHRAE Winter Conference, Las Vegas, NV, United States.

Relate air quality and other factors to comfort and health symptoms reported by passengers and crew on commercial transport aircraft (part 2) (ASHRAE research project 1262 RP). ASHRAE.

Potential of commercial air quality sensors to detect bleed air contamination events. (Report No. RITE-ACER-CoE-2015-1). National Air Transportation Center of Excellence for RITE/ACER Program. Auburn University.

Bleed air oil contamination particulate characterization. [Master's thesis, Kansas State University], K-State Research Exchange.

VIPR3 data collected by Kansas State University, a preliminary review. (Report No. RITE-ACER-CoE-2-15-2). National Air Transportation Center for Excellence for RITE/ACER Program. Kansas State University.