Understanding cabin air quality

Indoor air quality in the context of health and safety of airline passengers and crew members

Cabin air quality assessment of long-term effects of contaminants
© Sven Schuchardt

The quality of the air that passengers and aircrews are exposed to on board commercial transport aircraft has been at the core of a continuing debate for the past 60 years, both from the health and the safety points of view. This debate about cabin or cockpit air quality (CAQ) addresses most specifically single cabin/cockpit air contamination (CAC) events – e.g. due to potential oil leaks – and the intrinsic quality of the cockpit/cabin air in normal operating conditions.

A number of investigations and research projects have been conducted by various scientific teams, involving in-flight measurements, but so far has not allowed a complete characterization of the chemical compounds involved in CAC events, determination of sources and exposure levels to contamination, nor performance of comprehensive toxicological risk assessment for such events.

EASA, supported by the European Commission, has launched the new research project ”Cabin air quality assessment of long-term effects of contaminants” aimed at collecting additional scientific evidence concerning CAC events to root more extensive assessment of health risks and to support the evolution of aviation standards in this subject area.

The need and scope for additional scientific evidence were determined at the EASA workshop 2020 (go to the workshop website) together with the stakeholders who were actively involved there.

Our approach

The vision of the CAQ III project is to minimize current knowledge gaps in health risk assessment of oil-related “fume events” in aircraft in a reliable, efficient and cost-effective approach, bringing together the expertise and knowledge of all relevant disciplines and stakeholders. CAQ III will unite researchers, regulators and safety scientists from industry to reduce the uncertainties in risk assessment and enhance its practical applicability in line with the requirements of the regulatory authorities. In addition, the CAQ III partners will develop new mitigation strategies to better protect passengers and crew members in commercial aircraft from potentially hazardous chemicals.

The aim of the project is to provide a comprehensive physicochemical characterization of the compounds resulting from engine or APU oil leakage or dislodgment of deposits and their impact on cabin air quality. Such characterization will be obtained through a series of measurements performed in controlled environments that are representative of flight conditions.

The measured particulates and gases, their quantities, particle types and properties, their mixture and partitioning between gas and aerosol particulate phases will support the identification of toxicological hazards and the assessment of exposure levels for crews and passengers.

© Fraunhofer ITEM, Ralf Mohr

Project partners combine state-of-the-art expertise

CAQ III is a leading project to address the oil leakage-driven toxicological impact on cabin air quality and future risk assessments.

Therefore, we ensure scientific excellence backed up by regulatory relevance by recruiting leading experts from academia, research institutions and large industry. Partners combine state-of-the-art expertise in human toxicology, exposure assessment, molecular biology, analytical chemistry, biostatistics, aeronautical engineering and chemical risk assessment, as well as expertise in management and dissemination.

The CAQ III project pools first-class knowledge for its envisaged systematic health effects studies on oil-related “fume events”: state-of-the-art inhalation toxicity testing (RIVM), neurotoxicological analysis and biomonitoring (HMGU, RIVM, NRCWE, InstPharmToxBw, Fraunhofer ITEM) and metabolomics screening (Fraunhofer ITEM). In addition, CAQ III aspires to create the broadest possible impact for cabin air quality assessment and thus operate within the realms of the main European regulatory bodies. 

Fraunhofer ITEM already carried out the two previous projects (CAQ I and CAQ II).

Cabin Air Quality III – project structure

© Fraunhofer ITEM

Work packages in detail

Toxicology and health hazard identification

Owner: NRCWE (Denmark)

Work Package 1 will:

a) Collect information on contaminants and their measured levels in cabin air from the literature and compare these with those measured during the simulated CAC events, to select contaminants for further study

b) Collect information from the open literature on the hazards of the main contaminants, with a specific focus on symptoms reported by aircrew personnel  and passengers in context with perceived cabin air contaminations 

c) Identify hazards of the selected contaminants from the collected literature 

d) Identify gaps in the toxicological literature 

e) Develop recommendations for a complete toxicological risk assessment (with a focus on symptoms reported in flight personnel and passengers)

CAC event simulation and chemical characterization

Owner: Fraunhofer IBP (Germany)

In WP2, we will generate controlled and realistic bleed air oil contamination events to thoroughly characterize the fume composition by detailed online and off-line physicochemical analyses. We will perform standardized controlled exposure experiments for toxicological assessment in WP3.

We will load HEPA filters in a defined way for comparison with collected HEPA filters from in-service aircraft in WP4. This will be achieved by a Bleed Air Contamination Simulator (BACS) emulating the air supply system of an aircraft from the bleed port with high pressure and temperature conditions to the cabin with more or less ambient conditions to ensure that controlled oil contamination undergoes similar expansion and cooling steps along the air path.

Toxicity test and biomonitoring

Owner: RIVM (The Netherlands), HMGU (Germany)

We will address the question of whether it is plausible that bleed air contamination can result in neurotoxicity after inhalation. We will study these effects in rodents that will be exposed for 4 weeks at various exposure concentrations to air contaminated with pyrolysates of the most common engine oil in commercial aircrafts.

Tests to assess the potential neurotoxicity of the fumes at levels that will not result in marked lung effects include a battery of neurobehavioral tests (e.g. sensory, emotional and cognitive impairment tests). In addition, we will analyze biomarkers in blood and assess the histopathology in lung and brain. Care and use of animals for scientific purposes is guided by ethical and animal welfare standards following the 3Rs principles (replacement, reduction, refinement).

HEPA filter, ground aircraft test and ESC sampling

Owner: Fraunhofer ITEM (Germany)

WP4 includes the totality of analytical work with HEPA filters and components of the environmental control system (ECS) collected after use in real world (field study) as well as with the samples collected in a ground aircraft test and BACS (cp. WP2). To this end, all relevant methods and standards will be assessed and established/validated as appropriate. This analysis will allow identification of possible contamination patterns following oil leakage events.

Scientific community and stakeholder consultation and result dissemination

Owner: all previous

In WP5, we will communicate all CAQ III achievements and applications of project results internally and externally via a tailored communication strategy. WP5 will provide interfaces for dissemination of the results and promote the discussion and exchange of expertise between the consortium and all relevant stakeholders. WP5 will ensure that all different target groups are well informed about the project progress and impact on safety assessment by the most appropriate and modern dissemination and communication strategies.

Contact us about Cabin Air Quality III

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