Saharan dust on your car

The storm leaves the ergs of North Africa. In two or three days it crosses the Mediterranean Sea and the Balkans; it rains over it and it lands — sometimes on your car.

What is the dust, exactly? Fine rock particles — quartz and iron oxides, thinner than a hair. The larger ones, a few microns across, fall faster; the fine ones stay airborne and can be breathed deep into the alveoli. That is why the deposit on your car looks rust-red: iron oxide colours the dust.

Rain over the cloud and the dust comes down. Without rain, it stays aloft — visible as a milky, yellowish or orange sky, and felt more than seen. When it rains, the drops pass through the cloud and land as a red rain (or "mud rain"): not a substance hidden in the clouds, but desert rock washed out of the atmosphere.

The instruments record it every hour. Europe's CAMS reanalysis, produced by Copernicus, simulates the whole atmosphere from satellite and ground measurements; the dust values below are reanalysed from 1 January 2018 to 11 November 2026. A second network, real measurements from Romanian ground stations, confirms the episodes — and is used below as the falsification test.

Pick your city. The threshold used here: a daily maximum of at least 25 µg/m³ of dust, per the CAMS reanalysis — the full series, hour by hour, January 2018 to 11 November 2026.

Compared with European cities

Athens measured 5.4 times more days than Bucharest (177 versus 33); Rome, nearly three times (93). Vienna (13) and Warsaw (13), under half. Simple arithmetic: the closer to the source, the more often it hits you.

The bar: a daily maximum of at least 25 µg/m³ of dust in at least six of the sixteen Romanian cities measured. 29 days crossed it, in 15 episodes. Source: CAMS; press confirmation included where it exists.

The table scrolls sideways →

Peak = the highest hourly value on that date, in the hardest-hit city in the series. “Verified in the press” means ANM or at least two outlets reported the episode in the same window. For days tagged “measured”, the network says one thing; the press, from what could be consulted, says nothing.

This page doesn't take the press at its word, and it doesn't take the instruments at theirs either. Here is how both were checked.

The two networks

• CAMS (Copernicus Atmosphere Monitoring Service) — the atmospheric reanalysis produced by the EU's Copernicus Service, provided via Open-Meteo: dust, PM10 and PM2.5, hour by hour, from 1 January 2018 to 11 November 2026, for sixteen Romanian cities and — for comparison — Athens, Rome, Vienna and Warsaw.
• EEA (European Environment Agency) — real measurements from Romanian ground stations, daily validated values: about 72 stations report each day, in 2013–2025. This network was used as the falsification test for CAMS, not as a story in itself.

The test the data could have failed

If CAMS “sees” a real episode, the ground stations should breathe the same day. The 29 national dusty days (≥25 µg/m³ in six of sixteen cities) were compared with every other day in 2013–2025 on which EEA stations reported:

What this page does not know

This is not a laboratory conspiracy. Saharan dust is not “substances sprayed by aeroplanes” and is not uniquely toxic by itself. It is ground-up rock. The real risk is particle size: the fine ones reach deep into the alveoli — which is why people with asthma, the elderly and young children are the category to watch on dusty days, exactly as ANM and the respiratory physician Beatrice Mahler advise (Digi24, 24 April 2024).

There is no “off” switch for the Sahara. There are, however, a few reflexes that make a dusty day bearable.

1. Close the windows and keep the air conditioning on recirculation on expected dusty days (ANM usually announces an episode one or two days ahead). A short airing, in the morning, if needed.
2. Wash the car after rain, not before. The deposit shows only once it rains; a wash done on an announced day is re-dusted within hours.
3. Asthma, COPD, small children, the elderly: avoid prolonged outdoor exertion during episodes and keep your reliever medication at hand. A cotton mask does not filter fine dust — if you have asthma, follow your doctor's advice, not a scarf.
4. Dry sweeping throws the dust back into the air. Wet sweeping or a hose binds it to the ground.
5. Follow the real sources: ANM (meteoromania.ro) for warnings; Copernicus (copernicus.eu) for the CAMS dust maps; the ANPM stations (RNMCA) for the air next to you.
6. How to recognise a dusty day: a milky-yellow sky, an orange sunset, uniform orange deposits on cars and plants after rain, and ANM bulletins mentioning “dust of Saharan origin”.