Risk of volcanic smog, acid rain following Kilauea eruptions
Thursday, May 17, 2018, 2:48 PM - Residents of Hawaii's Big Island could face a couple of additional concerns in the days ahead, after already dealing with lava flows creeping across the landscape and now immense eruptions of ash into the sky - pooling sulphur dioxide emissions from the volcano could result in volcanic smog and acid rain.
This story has been updated.
As Mount Kilauea continues to erupt, with new fissures opening up and two immense eruptions of volcanic ash, one blasting over over 9 kilometres into the sky, another concern is lurking on the horizon.
Sulphur dioxide gas, or SO2, is being released into the air from these eruptions. This colourless gas, which smells like burnt matches, is not only hazardous on its own - potentially irritating the skin, eyes, nose and throat of anyone coming into contact with it and breathing it in - but it is also the main component in two other hazards, volcanic smog and acid rain.
Watch Below: Silent danger is impacting people under threat by the erupting volcano in Hawaii
According to the United States Geological Survey (USGS), volcanic smog, or 'vog', occurs when a combination of sulphur dioxide, water vapour, oxygen and dust, chemically reacts under exposure to sunlight, to produce a visible haze of sulphuric acid particles and other sulphate compounds.
Exposure to vog can result in headaches, difficulty breathing, stinging eyes and sore throat, and it can induce asthma attacks, and aggravate preexisting respiratory illnesses. Humans and animals are impacted by these effects, and vog can also damage plants.
If it happens to rain while vog is lingering over an area, the sulphuric acid particles will join other condensation nuclei in producing cloud droplets, which can then be caught up in rain formation, and produce acid rain.
While there are sometimes some rather dramatic ideas of acid rain burning like battery acid, the slightly acidic water that falls from these clouds feels like any other rain shower, and is not immediately dangerous. However, this acid water can pollute drinking water supplies, by leeching lead from pipes, it can damage plants, and it can even increase the rate of corrosion (rusting) of exposed metal objects.
According to the US National Weather Service, for today and tonight, May 17, 2018, due to sea breezes and upslope winds, vog concentrations "vog will be particularly thick today and this evening on the Big Island because the plume will collect over the island, particularly across the Puna and Hilo Districts and the saddle area, to the southwest of the Big Island.
The three animations below show the forecast probability of seeing vog concentrations, of any level, of moderate levels, and of unhealthy levels, respectively, for May 17 and 18, 2018.
Probability of seeing volcanic smog (vog), of any concentration, over Hawaii's Big Island, May 17-18, 2018. Credit: VMAP/University of Hawaii
Probability of seeing volcanic smog (vog), of MODERATE concentration, over Hawaii's Big Island, May 17-18, 2018. Credit: VMAP/University of Hawaii
Probability of seeing volcanic smog (vog), of UNHEALTHY concentration, over Hawaii's Big Island, May 17-18, 2018. Credit: VMAP/University of Hawaii
NWS Honolulu has issued an Ashfall Advisory, stating: "Volcanic ash is expected to reach immediate vicinity of the Kilauea Volcano Summit (Halemaumau Crater), including Volcano and Glenwood. If additional large explosions occur, winds aloft could push the resulting ash to communities of lower Puna such as Pahoa and Kapoho, south to the shoreline."
This advisory is in effect until 6 p.m. HST, Thursday, May 17.