Volcanic smog, also known as vog, is a type of air pollution that forms when a volcano erupts and releases gases into the atmosphere. The gases released by volcanoes include sulfur dioxide, carbon monoxide, and other harmful gases, with sulfur dioxide being the most harmful. When these gases react with oxygen, moisture, and sunlight in the atmosphere, vog forms. Vog is a hazy mixture of sulfur dioxide gas and aerosols, which are primarily sulfuric acid and other sulfate compounds. Vog can irritate the lungs and make existing lung problems worse, and it poses a health hazard by aggravating preexisting respiratory ailments. Vog can also reduce driving visibility and contaminate household water supplies by leaching metals from building and plumbing materials in rooftop rainwater-catchment systems.
Vog can negatively affect human health and agriculture, and acid rain can be generated in areas where vog is present, which could damage crops and affect metal roofs and buildings. People who may be particularly sensitive to vog are those with health conditions such as asthma, lung disease, and heart disease, the elderly, pregnant women, and children. To protect against vog, it is advised to avoid outdoor activities, shut doors and windows to black out vog, cover your nose, ideally with an N95 facemask, and drink plenty of water to avoid throat irritation or constriction. Running an air conditioner or dehumidifier can also help remove the particulate sulfur compounds and acid gases from indoor air.
