ASIDE from being a fiery spectacle of nature, there's more to volcanoes than meet the eye -- they are a force to be reckoned with. A single volcano has the ability to completely change the world's entire atmosphere, maybe even permanently.

In the Philippines, which sits at the western edge of the Pacific Ring of Fire, living near volcanoes is commonplace, especially in the province of Albay, where sits Mount Mayon, the most active volcano in the country.

Mount Mayon recently exhibited increased activity, which includes more lava flows and fountaining, and emission of volcanic gases, like sulfur dioxide.

The Philippine Institute of Volcanology and Seismology (Phivolcs) said the current activity of Mayon is still "far from the peak explosion," which may come in the coming weeks.

No stranger to volcanoes

Southeast Asia is one of the most geologically-active regions of the world, if not the most, and had been home to the most destructive and powerful volcanic eruptions in history.

Some of the historic explosions in the region have made a critical impact to the atmosphere. They include the explosion in Tambora, Indonesia, in 1815; Pinatubo, in the Philippines, in 1991, which cooled the entire world by half a degree Celsius; Mt. Samalas, Indonesia, in the 13th century, which may have plunged medieval Europe into a series of famines due to anomalous weather changes that followed; and Krakatoa in 1883, also in Indonesia, which also cooled the entire world.

In the Philippines, it is easy to feel the effects of a rumbling volcano -- ash fall, difficulty of breathing, or even crop failure, and while we already know the long-term results of volcanic eruptions, it is also important to take into account some finer details when it comes to their effects.

Atmospheric and environmental effects

Mylene Cayetano, Ph.D., head of the Environmental Pollution Studies Laboratory of the Institute of Environmental Science and Meteorology at the University of the Philippines Diliman, said the most common cause for concern is the fine dust coming from pyroclastic density currents.

"The fine dusts coming from the pyroclastic density current, or uson, due to its small size, can be resuspended in the air, and may eventually reach the residential areas outside of the danger zone. Then, if not washed off by rain, may spread farther. If inhaled, these dusts may trigger premature asthma attacks, allergic rhinitis, throat irritation, runny nose or sore eyes," she said.

Cayetano, a chemist, also pointed out that the sulfur dioxide in the atmosphere may become acid rain in a matter of hours, which can injure the skin and damage crops and infrastructure, as well as disrupt bodies of water.

"Acid rain may impact the surrounding vegetation by damaging the leaves and crops, due to its corrosive character. The acid rain can directly contribute to the acidity of the ground and thus reducing the potential of beneficial microorganisms in the soil to thrive, and essential soil nutrients to be available, thus reducing the overall fertility of the affected area," Cayetano added.

"With regards to fresh bodies of water, acid rain can also increase the alkalinity of lakes, rivers, and even those dedicated for aquaculture. When the alkalinity is altered, the growth of phytoplankton necessary for feeding fish might be inhibited, thus threatening the habitat of fish," she added. (PR)