Even volcanic ash can start fires where it lands. Magma gives off poisonous gases, including sulfur fumes and carbon monoxide. The most dangerous gas is carbon monoxide, which is invisible and odorless. It collects in valleys where it becomes more dense. People and animals in the valley will die.
Sulfur is a strong, yellow substance and can cause people and animals to cough.
People and animals with lung problems die if the sulfur becomes too strong. As lahar flows down mountain sides, it can wash away houses and cause as much damage as the lava. Volcanoes can be just as devastating as earthquakes, tornadoes, hurricanes or other natural disasters. Many lives are lost and damage to buildings and land is very expensive. Now that volcanologists are able to better predict an eruption, more lives can be saved.