HILO, HI — Hawaii residents have no doubt noticed the clouds of vog — volcanic smog — cloaking the Hawaii islands for the past few weeks. The mixture of gases and aerosols (tiny particles of dust and droplets) is formed when volcanic gas reacts with moisture, oxygen and sunlight during volcanic activity. The vog cloud comes from the Big Island’s ongoing volcanic activity.

Vog is particularly hard to study and potentially more harmful than either gases or particles alone. Those same scientists say that the aerosols are acidic and tend to remain in the lungs.

Compared to studies done about urban smog and pollution, vog chemically shares many qualities with smog and could have similar detrimental impact on those with asthma and other respiratory illness.