Volcanic Emissions: Understanding Air Pollution From Volcanoes

Volcanic eruptions can result in serious health hazards. When a volcano erupts, it releases harmful particles, including volcanic gases and ash, into the air. Volcanic gases that pose the greatest potential hazards are sulfur dioxide, carbon dioxide, and hydrogen fluoride. Inhaling volcanic gases and ash can be harmful to your health, especially if you have asthma. While volcanoes have contributed to global warming by producing significant amounts of carbon dioxide and other greenhouse gases, human activities emit 60 or more times the amount of carbon dioxide released by volcanoes each year.

Human activity vs volcanic air pollution

Volcanic eruptions can result in serious health hazards. When a volcano erupts, it releases harmful particles, including volcanic gases like sulphur dioxide, carbon dioxide, and hydrogen fluoride, as well as ash, into the air. These gases can be harmful to human health, particularly for those with respiratory issues such as asthma, and can also lead to acid rain and air pollution downwind from the volcano. Additionally, ash from volcanic eruptions can travel hundreds to thousands of miles, causing issues such as eye irritation and respiratory problems. In some cases, volcanic ash can even lead to the shutdown of drinking water and wastewater treatment facilities by clogging or damaging equipment.

However, when it comes to the overall impact on air pollution, human activity far surpasses volcanic emissions. Human activities, mainly the burning of fossil fuels and industrial processes, emit 60 or more times the amount of carbon dioxide released by volcanoes annually. While large and violent volcanic eruptions may temporarily match the rate of human emissions, they are too infrequent to rival the constant human emissions over a year. In fact, several individual U.S. states emit more carbon dioxide in a year than all the volcanoes on Earth combined.

The argument that volcanic emissions are the primary driver of climate change is not supported by scientific evidence. While volcanoes can impact climate change, particularly through the release of sulphur dioxide and carbon dioxide, the effects are typically short-term and regional. On the other hand, human activities have consistently increased atmospheric CO2 levels year after year, regardless of volcanic activity. This consistent trend indicates that human-caused emissions are the dominant factor in the rise of carbon dioxide concentrations globally.

While volcanic activity may have contributed to global warming and mass extinctions in the deep geologic past, current volcanic activity does not occur on the same massive scale. Today, volcanic eruptions can even have a temporary cooling effect on the planet due to the release of sulphur dioxide and other particles that reflect radiation from the Sun back into space. Therefore, in the context of air pollution and climate change, human activities are far more significant contributors than volcanic emissions.

Harmful volcanic gases

Volcanic activity releases harmful gases that can negatively impact human health, vegetation, and infrastructure. These gases are emitted both during eruptions and through underground magma when the volcano is not erupting. The five main gases that pose a health threat to humans are carbon dioxide (CO2), hydrogen sulfide (H2S), radon, sulfur dioxide (SO2), and hydrogen halides (HF, HCl, and HBr).

Carbon dioxide is a significant component of the Earth's atmosphere, constituting approximately 0.04%. While it is typically quickly diluted to low concentrations after volcanic emissions, it can become trapped in low-lying areas, reaching much higher concentrations. Breathing air with more than 3% CO2 can lead to adverse health effects such as headaches, dizziness, increased heart rate, and difficulty breathing. At mixing ratios above 15% carbon dioxide, can cause unconsciousness and death.

Hydrogen sulfide is a colorless, flammable gas with a strong, offensive odor. It is highly toxic at higher concentrations, causing irritation of the upper respiratory tract and pulmonary edema with prolonged exposure. Exposure to 500 parts per million can lead to unconsciousness and death within an hour.

Radon is a radioactive gas produced by the decay of uranium deep within the Earth. It can accumulate to harmful levels in confined spaces, such as buildings, and pose a severe health hazard.

Sulfur dioxide (SO2) is another critical volcanic gas. When released from a volcano, it reacts with other atmospheric components to form sulfate aerosols, leading to the formation of volcanic smog or "vog." These aerosols can remain in the stratosphere for years, causing short-term climate changes and global cooling. Additionally, SO2 contributes to acid rain, which can irritate the skin and eyes, damage plants, and accelerate the rusting of metal surfaces.

Hydrogen halides, including HF and HCl, are quickly diluted in the air but can affect water supplies near the eruption. They are acidic and can irritate the moist surfaces of the respiratory tract and lungs.

It is important to note that volcanic gases are often colorless and odorless, making it difficult to detect and avoid exposure. Additionally, the health effects of exposure can vary depending on factors such as gas concentration, length of exposure, and individual sensitivity.

Volcanic ash and its effects

Volcanic ash is composed of tiny fragments of jagged rock, minerals, and volcanic glass. It is a product of explosive volcanic eruptions. When a volcano erupts, gases inside its magma chamber expand and violently propel molten rock (magma) out of the volcano. The force of these explosions shatters and propels the liquid rock into the air, where it cools and solidifies into volcanic rock and glass fragments. These rock fragments can mix with solidified lava fragments in the air, creating an ash cloud.

Volcanic ash can have a range of effects on the environment and human health. Firstly, ashfall can cause minor to major damage to vehicles and buildings. It can also contaminate water supplies, disrupt sewage and electrical systems, and damage or kill vegetation. After ashfall, affected airports must be closed until the ash is removed due to the hazard it poses to jet engines. Additionally, volcanic ash can create eye and upper airway irritation, with inhalable fine particles causing respiratory issues. In some cases, volcanic ash can lead to skin irritation as well. The impact of volcanic ash depends on various factors, including the distance from the volcano, the physical properties of the ash, the amount of ashfall, and the community's preparedness.

The effects of volcanic ash on visibility and climate are also significant. Plumes of volcanic ash can spread over large areas, reducing visibility and sometimes causing complete darkness during daylight. This reduction in visibility can be dangerous for aircraft, as it can damage flight control systems and cause engine failure. Furthermore, volcanic ash can reach the stratosphere, where it reflects incoming solar radiation and absorbs outgoing land radiation, leading to a cooling of the Earth's temperature. However, the overall impact of injected ash on climate change is considered minimal, as most of it is removed within a few weeks.

While volcanic eruptions release carbon dioxide, a greenhouse gas, they contribute significantly less than human activities. Human activities emit 60 or more times the amount of carbon dioxide released by volcanoes annually. Large, violent eruptions may match human emission rates during their brief duration, but they are too rare to rival humanity's annual emissions. Therefore, while volcanic ash and gases can have localized impacts and temporary global cooling effects, human activities remain the primary driver of long-term global warming.

Impact on climate change

Volcanic eruptions release molten rock, or lava, from deep within the Earth, forming new rock on the Earth’s surface. However, the largest and most explosive eruptions can also impact the atmosphere. The gases and dust particles thrown into the atmosphere during large volcanic eruptions can influence climate change.

Volcanoes emit carbon dioxide in two ways: during eruptions and through underground magma. Carbon dioxide from underground magma is released through vents, porous rocks and soils, and water that feeds volcanic lakes and hot springs. Much of the carbon dioxide released by volcanoes is emitted by the degassing of subterranean magma when the volcano is not erupting.

Volcanoes emit around 0.13 to 0.44 gigatons of carbon dioxide per year. In comparison, human activities were responsible for 35 billion metric tons of carbon dioxide emissions in 2010, about 80 to 270 times larger than volcanic emissions. While volcanoes can inject significant amounts of carbon dioxide into the atmosphere, human emissions are ceaseless and increasing every year.

Volcanoes also emit other gases and particles that can influence climate change. For example, volcanic ash can cause local air pollution and impact the health of vulnerable individuals, livestock, and infrastructure. Additionally, volcanoes emit sulfur dioxide, which can lead to acid rain and cause global cooling. When sulfur dioxide is injected into the stratosphere, it combines with water to form sulfuric acid aerosols. These aerosols increase the reflection of radiation from the Sun back into space, cooling the Earth's lower atmosphere. Several volcanic eruptions during the past century have caused a decline in the average temperature at the Earth's surface for periods of one to three years. For example, the 1991 eruption of Mount Pinatubo injected a 20-million-ton sulfur dioxide cloud into the stratosphere, causing the Earth's surface to cool by up to 1.3 degrees Fahrenheit for three years.

While volcanoes can have a significant impact on climate change, the overall effect is complex and depends on various factors, including the magnitude and frequency of eruptions and the specific gases and particles emitted.

Health hazards and precautions

Volcanic eruptions can result in a wide range of health hazards. When a volcano erupts, it can release harmful particles, including volcanic gases and ash, into the air. These can be harmful to human health, especially for children, older adults, and people with lung diseases, who are more susceptible to gases and smoke.

Volcanic ash can be abrasive and corrosive, and it can cause respiratory irritation, trigger asthma attacks, and lead to coughing and wheezing, especially in individuals with sensitive airways. In some cases, exposure to volcanic ash can even be fatal. The ash can also get into the eyes and cause scratches, especially in windy conditions. Moreover, heavy falls of tephra, a general term for any fragmentary material emitted from volcanoes, can lead to building collapse due to the weight of ash on roofs.

Volcanic gases, on the other hand, can be odorless and invisible, making it difficult for people to avoid exposure. These gases, such as sulfur dioxide, can cause global cooling, while volcanic carbon dioxide can contribute to global warming. Gases like sulfur dioxide and carbon dioxide can also lead to acid rain and air pollution downwind from a volcano. Additionally, volcanic emissions can include harmful particles such as sulfate aerosols and heavy metals, including lead and mercury.

To protect yourself from the health hazards of volcanic air pollution, it is important to follow local guidance and take precautions, especially if you have asthma or other respiratory conditions. Stay indoors as much as possible, and keep indoor air clean by closing doors and windows, turning off ventilation systems, and using air conditioning only in the "recirculate" setting. If you need to drive in affected areas, keep your windows and vents closed. Ordinary dust masks are not effective against the fine particles in volcanic ash, so consult a physician about specialized masks like N-95 masks.

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