Saharan dust on the Côte d'Azur: is it dangerous for health?

Residents of the Côte d’Azur are once again seeing an orange sky and a thin layer of dust on their cars. Alarming messages about the radioactivity of these deposits are circulating on social media. We examine how dangerous the sand rains are and what precautions should be taken.

Nature of the phenomenon: where the sand dust comes from

Every spring and early summer air masses laden with the finest particles of desert sand sweep over the Mediterranean. This natural phenomenon, known as calima, occurs when strong winds in North Africa lift millions of tonnes of sand and dust into the atmosphere. These particles are then carried thousands of kilometres and settle on the European coastline.

In recent days residents of the Alpes-Maritimes have witnessed an especially intense episode: the sky turned ochre-brown and a thin layer of reddish dust formed on cars and terraces. The prefecture of the Provence-Alpes-Côte d’Azur region declared an episode of PM10 particulate pollution affecting the entire coast, including the department that usually suffers less from such episodes than its neighbours (ICI). A similar wave of polluted air already covered southern France in June — authorities then also declared an elevated alert level (“A wave of polluted air hit the southern regions of France”).

Dispelling the myth of radioactivity

Information is circulating on social media claiming that Saharan dust is radioactive due to French nuclear tests in the Sahara in the early 1960s. Scientists refute this: the isotopic composition of the dust does not match the trace of French explosions, but corresponds to global atmospheric fallout from tests by the USSR and the USA in the 1950s–1960s, which at the time contaminated soils worldwide (The Conversation).

Specialists from France’s Nuclear and Radiological Safety Authority (ASNR) regularly measure radioactivity levels during such episodes. According to them, the median concentration of caesium-137 in the settled dust is about 14 becquerels per kilogram, compared with the EU limit for foodstuffs of 1000 Bq/kg. The estimated dose from inhaling such particles is roughly 100 million times lower than the level permitted by EU standards (ASNR) — in other words, the radiological threat from Saharan dust is negligible.

Real danger: respiratory risks

The main threat posed by sandstorms is not radioactivity but the impact on the respiratory system. The World Health Organization classifies such episodes as potentially hazardous to health, especially for people with chronic conditions (Allo Docteurs).

• The finest dust particles (PM10 and PM2.5) can penetrate deep into the lungs
• They can irritate mucous membranes and the throat
• People with asthma or COPD may experience symptom exacerbations
• Dust can carry fungal spores, pollen and other biological particles that worsen allergic reactions

Impact on vulnerable groups

Those most at risk are people with weakened health: the elderly, children, pregnant women and patients with cardiovascular and chronic lung diseases. According to the Air Pollution Study Association (APPA), during such episodes the number of consultations for cough, sore throat and breathing difficulties increases — especially among people with chronic respiratory conditions (APPA).

Practical recommendations

To minimise the impact of dust particles on the body, it is worth following a few simple rules. During active dust fallout it is better to reduce time spent outdoors, especially in the morning.

People in risk groups should use protective masks: FFP1 or FFP2 retain the larger particles that are dangerous for the bronchi. It is also recommended to keep windows closed and, if possible, to use air purifiers indoors. Climate change on the coast is making such episodes more noticeable year after year — more in the feature “The Côte d’Azur’s climate in 2050”.

Forecast: when will the dusty period end

According to meteorologists, the Saharan dust episode on the Côte d’Azur should not last long: westerly winds are expected to disperse the pollution and prevent new clouds from North Africa, while storms with rain (locally up to 15 mm of precipitation between Antibes and Menton) will help wash the dust from surfaces.

Experts emphasise that, despite the temporary inconvenience, Saharan dust is a natural phenomenon that does not pose a serious threat to the health of most people. However, observing basic precautions will help reduce potential risks to the body.

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Photo: Zhanna Alimkulova / Pexels