Costa Rica's National Emergency Commission (CNE) issued a red alert on 5 January after Turrialba Volcano continued to spew ash and debris in the Central Valley.
The active volcano has been erupting constantly for past two weeks and a combination of dry air and strong wind have increased the ashfall in the area, reported the Casa Presidencial, according to Tico Times.
Buildings, trees and cars were seen completely covered in ash throughout the capital city of San Jose and the broader Central Valley.
Ashfall has also become a pressing concern in cities as far north as Heredia. Moreover, westernmost city of Costa Rica, Escazu is also facing the crisis.
Other places which witnessed ashfall are Barva, Moravia, Santa Barbara, Guadalupe, Coronado, Santo Domingo, Tibas, Pavas, Carrizal, Sabanilla and Alajuela. The National University's Volcanological and Seismological Observatory of Costa Rica (OVSICORI) blames southwest winds for carrying the ashes across the country, as reported by the news website.
Meanwhile, on 5 January, Dr. Mauricio Mora of the University of Costa Rica's National Seismological Network (RSN) warned people of San Jose of more ashfall from Turrialba Volcano. "These episodes are separated by periods of low ash emissions and light harmonic tremors," said Mora, according to reports.
"The winds are blowing southwest this morning, according to data from the National Meteorological Institute (IMN), and will, therefore, continue to affect the Central Valley," added the expert.
It was reported that CNE has laid down guidelines for the public.
Authorities have instructed municipal emergency commissions to be alert of the situation and keep dishing out information to their communities.
CNE also advised people to stay indoors and avoid stepping out. In dire situations, if people have to leave the house where significant ash is present, the government said, they should cover their mouths and noses with towels or dust masks.
People were also urged not to consume food or drink outside the house in places where high levels of ash is present.
Flight service improved on Thursday after cancellation and delays on Wednesday for which hundreds of passengers suffered.