LA PALMA, Spain—Authorities told several thousand residents of La Palma to stay home because of worsening air quality as the erupting volcano on the Spanish island spewed red-hot lava and thick clouds of black smoke. Emergency services issued a lockdown order on Friday night for people in Los Llanos de Aridane and El Paso, two of the worst affected towns. “The new lockdown is as a consequence of the meteorological conditions… that prevent the dispersion of gases and keep them at low levels of the atmosphere,” emergency services said in a statement. They said the lockdown would affect around 3,500 people. Those affected have been told to keep their doors and windows closed and to disconnect heating and air conditioning to prevent outside air from entering. Lockdowns had already been ordered in the areas of San Borondon, Marina Alta, Marina Baja, and La Condesa. About 6,000 people have been evacuated …