Authorities on the Spanish island of La Palma have told the 7,000 residents of the town of El Paso to stay home if possible due to the poor air quality caused by the erupting volcano.
The gases escaping from the volcano are not sufficiently clearing out due to the current weather conditions, the La Vanguardia newspaper reported on Tuesday.
The volcano has been erupting steadily for weeks, spitting out ash, smoke and lava, and shows no immediate sign of ending its activity.
A second lava flow is about to reach the sea and is only 30 metres away from the coastal cliffs, state television RTVE reported.
Almost three weeks ago, the main flow of lava had already reached the Atlantic, creating a new spit of land that measured some 36 hectares on Sunday, meaning maps of the island will need to be re-drawn.
The authorities again warned that toxic fumes could form when the lava, which has a temperature of around 1,000 degrees Celsius, comes into contact with the salty seawater.
2,000 buildings destroyed
The volcano, which has no official name, began to erupt on September 19 for the first time in 50 years.
Since then, lava has destroyed almost 2,000 buildings, with 800 hectares of the island now covered in a metre-thick layer of lava.
Some 7,000 residents have been evacuated from their homes.
Flight operations had resumed on Monday after a two-day interruption. On Tuesday, however, there were many delays due to the difficult conditions and the danger to aircraft posed by volcanic ash.