A French study examining the indoor air quality of commercial aircraft found a consistent presence of ultrafine particles (UFPs) and black carbon (BC) in aircraft cabins. These two pollutants are widely associated with adverse health effects in scientific literature. Based on measurements taken under real operating conditions, some media coverage has described particle concentrations as “extremely high” during certain phases of flight.
UFP and BC measurements were analysed from 12 and 16 flights, respectively, operated by six and eight aircraft, respectively, across three aircraft types: the Airbus A220, A319, and A321. Four of the flights were domestic within France, four were to neighbouring countries, and eight were to other European destinations. Pollutant concentrations were tracked continuously from boarding to disembarkation, covering all phases of the journey.
The results show that exposure varied significantly depending on the flight phase. Longer flights were associated with lower average UFP concentrations, while extended taxiing times significantly increased levels of both UFPs and black carbon. The study also found that higher passenger numbers were directly linked to increased BC concentrations.
On certain aircraft, take-off and landing were characterised by sharp, short-lived spikes in UFP levels. In contrast, altitude, turbulence and the duration of meal services had no measurable impact on pollutant concentrations.
UFPs are extremely small airborne particles that can be inhaled deep into the lungs and, in some cases, can enter the bloodstream. They are produced by combustion processes, such as those from jet engines, road traffic and industrial activity. BC is a climate-warming pollutant and consists of soot-like particles that often carry toxic compounds on their surface.
Although some media outlets have described extremely high concentrations during boarding and taxiing, the study itself states that overall cabin concentrations were lower than those typically recorded in other transport environments, including taxis, buses, underground systems, and urban roadside areas. The elevated readings observed on aircraft were short-term peaks rather than sustained exposure levels.
The study did not assess health outcomes or define exposure thresholds. While long-term exposure to ultrafine particles (UFPs) and black carbon (BC) has been linked to cardiovascular and respiratory effects in epidemiological studies, recent scientific reviews suggest that evidence connecting short-term exposure spikes to immediate health impacts is limited.
In its 2021 update of global air quality guidelines, the World Health Organization (WHO) concluded that “the epidemiological evidence was insufficient to derive a guideline for UFP. WHO developed a best practice statement because of concerns with UFP health effects.”
Commercial aircraft cabins rely on a combination of outside air drawn from the engines and recirculated air filtered through HEPA (high-efficiency particulate air) systems. These systems are quite effective at removing particles from recirculated air, which is why the air on aeroplanes is often considered cleaner. However, pollutants can still enter the cabin during ground operations before filtration occurs.
Overall, the findings suggest that passenger exposure originates mainly from outdoor, airport-related pollution drawn into the cabin during ground operations rather than in-flight conditions. Researchers say this makes the issue particularly relevant for frequent flyers and flight crews, and it should be addressed by airport quality management teams. Occasional travellers appear unlikely to face a significant health risk based on the current evidence.
