QUITO, Ecuador -- Many residents of Ecuador's capital, Quito, are
                  wearing face masks and glasses and using umbrellas to protect themselves
                  from the cloud of ash spewing from the Guagua Pichincha volcano.

                  The cloud, up to seven miles (11 kilometers) high and 27 miles (44
                  kilometers) in diameter, darkened the afternoon sky Tuesday, and sent
                  many of the city's 1.2 million residents rushing home to close windows.

                  Volcanologists say the cloud is part of a slow decompression process that
                  started Monday and could last for months or even years.

                  Quito's Mayor Roque Sevilla says the ash eruption does not mean a major
                  eruption is imminent.

                  "This is more of a bother than a danger," he said.

                   Guagua Pichincha, which is 7 miles (12 kilometers) from Quito,
                   last erupted around 340 years ago.

                  Officials aren't taking chances

                  Authorities closed the city's international airport to prevent ash
                  from damaging planes. They did not say how many flights were canceled or
                  when the airport would be reopened.

                  Classes were also suspended in Quito schools, forcing about 400,000
                  students to stay home. They are expected to reopen on Wednesday.

                  Quito has been under a volcano alert since early last week, but the alert was
                  downgraded to "yellow" Monday because of reduced volcanic activity.

                  Quito surrounded by volcanoes

                  Guaga Pichincha is only one of nine active volcanoes surrounding Quito in
                  an area in the Andes known as "volcano alley."

                  Civil defense workers had to rescue an Australian climber and his
                  Ecuadoran guide from the Tungurahua volcano Tuesday, 106 miles
                  (170 km) from Guagua Pichincha. They were hurt by exploding gas
                  from the mountain.

                  Authorities have banned all climbing expeditions in the area until further
                  notice.

                           The Associated Press and Reuters contributed to this report.