Ultrafine particles from planes are causing health-threatening pollution not only to passengers, but also communities near airports, according to a study by French researchers.

In 2021, the Dutch Health Council and the World Health Organization (WHO) highlighted the growing evidence that ultrafine particles can cause lung inflammation, blood pressure and heart problems, along with risks to fetal growth. Later, a study of nearly 11 million people in the Netherlands found that exposure to ultrafine particles over several years was linked to early deaths including of lung cancer.

The Guardian reports that the team of researchers, including those from Université Paris Cité, placed a pack of instruments inside the passenger cabins of flights from Paris Charles de Gaulle to European destinations.

Ultrafine particle pollution in the cabin was very low when aircraft were at cruise altitude, but high concentrations of ultrafine particles were measured when passengers were boarding and when aircraft were taxiing — on average, more than twice those that the WHO defines as high.

This polluted air was gradually flushed from the cabin once airborne, but levels increased again on approach to landing, possibly from high concentrations close to flight paths and downwind from airports.

It was a similar picture for black carbon, or soot particles. These were also greatest when the aircraft was at an airport, and the study found that they spread.

Ultrafine particles from Charles de Gaulle could be detected more than 5km away. In London, ultrafine particles from Heathrow could be detected across west and central London, meaning they are being breathed in by millions of people.

The Guardian said aircraft remain relatively polluting, with little controls compared with road traffic and industry.