Costa Rica's Turrialba volcano spewed a large cloud of smoke and ash Tuesday afternoon, in what scientists said was the first activity of its kind in nearly 150 years, which prompted the evacuation of families who live at the foot of the mountain.

Red Cross spokesman Freddy Román told The Tico Times, as of 7 p.m. Tuesday, there were no reports of injuries but emergency workers were staying alert. He said contact with volcanic ash can cause respiratory or other health problems particularly among young children, people with asthma or pregnant women.

The Red Cross dispatched three ambulances and teams of rescue workers to the area, east of San José in the province of Cartago, in what Román described as “prevention and assistance operations.”

The National Emergency Commission (CNE) said in a news release late Tuesday that emergency workers evacuated 21 people from the town of La Pastora.

In May 2007 Turrialba began to show signs of increased activity, according to Juan Segura, director of Volcanological and Seismological Observatory of Costa Rica (OVSICORI). Scientists with the observatory have noticed higher seismic activity and gas emissions that burn and cause discoloration in the vegetation near the volcano, which hurts local agriculture and the livestock.

Segura said Turrialba's last major eruption was in 1864.

The Red Cross spokesman said for several months emergency teams have been planning and training with locals to prepare for a large-scale evacuation in the event of an eruption.