Volcanoes: Nature's Toxic Smokestacks

06/30/2010 05:12 am ET | Updated Nov 17, 2011

If powerful jet engines of a 747 jumbo jet can be choked to death in an instant by inhaling volcanic ash, what about delicate lungs of human beings? The sudden termination last week of all trans-Atlantic air flights to avoid the catastrophe of aircraft plummeting to earth from an encounter with volcanic ash from Iceland's Eyjafjallajokull, dramatically illustrates the fragile relationship between man and the environment. Especially on Earth Day, when we renew our enlightened understanding that industrial activities can poison our environment, it is sobering to realize that Nature does not revolve around an imperative to maintain Earth's environment for the health and welfare of human beings. The largest point source of sulfur dioxide in the United States is the Kilauea Volcano in Hawaii. Try fitting a catalytic converter to this "polluter."

Hot volcanic gases are extremely chemically reactive. Bromine released in a volcanic plume causes extensive ozone destruction. Ozone is the atmospheric gas that allows life on this planet to flourish by shielding organisms from the sun's deadly ultraviolet radiation. High concentrations of sulfur dioxide drive a caustic chemistry that degrades the atmosphere and attacks the respiratory system. Mercury and fluoride in the air and water can rise to toxic levels from volcanic eruptions. Fine particles of silica and other residues in volcanic ash pollute the air, block out sun stifling plant growth, and attack lungs. Respiratory infections increase sharply in people living in the vicinity of volcanoes, especially among children.

The Kilauea Volcano in Hawaii has been erupting continuously since 1983. In the Ka'u District of Hawaii, indoor sulfur dioxide concentrations are above the World Health Organization recommendations, raising special concern for indoor air quality in hospitals and schools. Studies of medical records and emergency room visits in nearby communities show that local residents have elevated incidence of bronchitis, increased prevalence of cough, phlegm, runny nose, sore throat, sinus congestion, wheezing and eye irritation.

A study in the aftermath of the Mount Asama eruption in Japan on September 1, 2004 found increased asthma in people living in affected areas. The risk of bronchitis doubled compared to unexposed communities, suggesting communities continuously exposed to sulfurous volcanic air pollution may have a higher risk of bronchitis across the life span. A review of mergency room visits after the Guagua Pichincha volcanic eruption in April 2000 in Quito, Ecuador found elevated rates of acute upper and lower respiratory tract infections, and asthma, especially in children. The rate of asthma doubled during the period of volcano activity.

Studies in experimental animals show that in addition to causing respiratory and cardiac illness, sulfur dioxide is a neurotoxin. Inhaled sulfur dioxide destroys DNA and protein by chemical oxidation causing systemic damage to the body's cells. The cellular destruction can be seen under a microscope in heart tissue, lung, liver, cerebral cortex of the brain, kidney and testes. Chemical analysis shows a dose-dependent increase in DNA damage in all cells of mice examined after inhaling sulfur dioxide. Damage to genetic material would fuel increased genetic mutation, cancer and have other destructive consequences.

Not only atmosphere, but water is also polluted by volcanoes. The water of Kagoshima Bay in Japan, which has a highly active volcano in its center, has dangerously elevated levels of mercury. People living in the Isparta Province of Turkey have mottled tooth enamel from high levels of fluoride leached from volcanic rocks into drinking water.

Clinging to this crust floating like slag on the Earth's molten core it is remarkably easy to forget that volcanoes have been shaping the geology and biology of this evolving planet for eons. This process began long before humans entered the scene and doubtlessly volcanoes will continue to do so long after homo sapiens succumbs to the same fate as dinosaurs, trilobites and the other marvelous biological creatures that have had their day on this third planet from the sun.

(You can read more about how the evolution of the Earth's atmosphere affects the brain in a chapter in the new book, The Other Brain,