It's a dubious honour for the capital of Baden-Württemberg, usually better known for its prosperity than for high concentrations of potentially cancer-causing particles in the air.
“It is recommended for drivers to switch to public transport or a bicycle, walk, or carpool,” a statement on the city website read.
“If possible, employees should agree with their employers to work from home or use flexible working times.”
Stuttgart's VVS public transport co-operative is also offering a discount worth the price of a month for customers taking out a new annual subscription before April 1st.
It's a move that echoes those made in French capital Paris, where politicians frequently order all vehicles with odd- or even-numbered registrations off the roads at times of peak pollution while offering free public transport.
But Stuttgart is a different case, as the city is perhaps best known as one of the strongholds of the German car industry.
Daimler and Porsche are both based in and around the city, along with many smaller car-parts manufacturers.
Weaning Stuttgarters off their almost half a million car journeys in and out of the city every day will be no easy task.
Stuttgart was already known to be the most polluted city in Germany thanks to a report from the Environment Ministry published in April last year, which found that it had the highest levels of fine particle pollution, nitrogen dioxide and sulphur dioxide.
Fine particles trapped at low altitudes
Fine particle alerts are issued by the city when German Weather Service (DWD) monitoring predicts very little movement of air on two successive days.
A layer of warm air high up prevents cold air closer to the ground from rising out of cities and valleys, leaving the particles that would ordinarily be borne away trapped with it at low levels. – where people might breathe them in.
This happens most often in winter, with the highest risk coming when there has been no rain or snow for several days.
According to the DWD, the high levels of fine particle pollution announced in Stuttgart today could last for up to a week due to weather conditions.
Say no to 'cosy stoves'
As well as asking citizens not to drive, a message on the city administration website asked people not to use extra wood-burning stoves in their homes during the fine particle alarm.
“These small wood-fired units frequently have serious problems with airborne pollutants,” the Stuttgart city website noted, adding that “they are more used for feeling cosy than for producing warmth.”
But going without stoves may be a big ask for Stuttgarters, as Germany shivered through the coldest night yet this winter on Sunday night – with temperatures well below freezing in the Baden-Württemberg capital.