In early May 2018, Kīlauea volcano became increasingly active, posing an increase in threat to respiratory health. The emission of gases such as sulfur dioxide from Kīlauea produces large amounts of respirable acid particles as the gases react with water vapor and sunlight, resulting in a visible haze called “vog”. Additionally, the lava lake at Kīlauea’s summit crater has fallen, leading to explosions of “ash” that have reached as high up as 30,000 feet above sea level. Finally, lava entering the Pacific Ocean boils sea water to dryness, creating thick clouds of “laze” that is filled with hydrochloric acid and tiny shards of glass. Depending on your location and wind direction and speed, vog, ash, and laze can reach hazardous levels of air pollution that are toxic to humans. This fact sheet serves to inform you of potential adverse health effects following exposure to these airborne products of volcanic activity. This outdoor air quality issue is relevant to other locations worldwide at risk for volcanic activity.