The Popocatepetl volcano just east of Mexico City has spit out a cloud of ash and vapour two miles high over several days of eruptions, and Mexico City residents awoke to find a fine layer of volcanic dust on their cars.
It has been years since the centre of the nation's capital has seen a noticeable ash fall because prevailing winds usually blow the volcanic dust in other directions. Ash fell earlier this week in some neighbourhoods on Mexico City's south and east sides.
The city's legion of car washers quickly wiped the fine coating from cars on Saturday with no apparent ill effects.
Claudia Dominguez, spokeswoman for the Mexico City civil defence office, said the very fine ash had probably been floating around the city from eruptions in previous days and had been brought to Earth by a rainfall late on Friday. She said no new ash fall had been reported on Saturday, despite continuous eruptions of vapour and ash into the air from the 15,000ft (5,450m) volcano.
While city residents were surprised by the talcum-like ash, inhabitants of towns nearer the volcano have had to deal with much thicker accumulations that have coated their crops, homes and sidewalks.
In San Pedro Nexapa, located about nine miles from the volcano, residents swept up small piles of ash from a few square yards of pavement. Some residents wore surgical masks to ward off the dust raised by passing vehicles.
Mexico's National Centre for Disaster Prevention raised the volcano alert from Stage 2 Yellow to Stage 3 Yellow, the final step before a Red alert, when possible evacuations could be ordered. A Stage 3 Yellow alert had been in effect during eruptions earlier this year until early June, when it was lowered.
US airlines cancelled at least one flight at Mexico City's airport on Friday as a precautionary measure, though airport authorities said the terminal was fully able to operate. Alaska Airlines had cancelled its route to Los Angeles, the airport press office said in its Twitter account. On Friday, four airlines cancelled a total of 17 flights "due to climate conditions and in accordance with their own internal policies," the airport said in a statement.
The volcano is about 40 miles from the airport, which is in turn a few miles east of the city's centre.
The Environment Ministry has urged residents to take preventive measures to deal with the ash, including wearing dust masks, covering water supplies and staying indoors as needed. Mexico City authorities recommend that people sweep up any ash and put it plastic bags to keep it from mixing with water and forming a concrete-like substance that can block drains.