How reliable are the trade winds

The trade winds died down starting Monday. For two days, there were intervals of high SO2 levels around the island. But today the trade winds returned and cleared the air by blowing the SO2 out to sea. Since the eruptions started 27 days ago, there have been only three days that the trade winds failed to clear the air from most of the island, May 17, 28 and 29.

The reliability of the trade winds varies with each month. As it turns out the most reliable month is July, the time of our reunion. If we get unlucky and the trade winds fail while we are there, we can expect the trade winds to return within a day or two.

Keep in mind that the SO2 does not mix evenly in the air. Bad air comes in pockets and last in an area for about an hour. For example, Hilo received no more than 75 minutes of SO2 in the Orange range on each of its three bad air days.

For where we are staying on the Kona side, the loss of trade winds means that SO2 can take a direct route across the island. But it is still over twice the distance to Hilo. The worst SO2 event in Kona was a 30 minute interval on May 28 of SO2 in the Yellow range. Remember that there is still a PM2.5 vog problem in Kona which was discuss in previous blog posts. In Kona, if the SO2 quality is in the Yellow range, then the PM2.5 quality could be in the Red range, unhealthy but not dangerous. So pollution masks should help.

One final thing, the trade winds are predicted several days in advance. The start and duration of bad air days are part of the weather forecast. The possible loss of trade winds should not be a concern for our trip.

Will masks help with vog

From the very start of the eruptions, the media has warned the public that masks would not work for SO2 gas. THIS report from CNN is typical. The gist of the article is, "the Hawaii Department of Health says no commercial mask sold in stores would actually do residents any good".

This is obviously not completely true since we see emergency workers using face masks with filter cartridges. These masks can be bought on Amazon for about $30. So certainly some commercially available masks will work.

What they meant by "store masks" was probably simple dust masks or surgical masks. These types of mask will not work on SO2 or PM2.5 sulfates. But what about high quality dust masks designed for heavy urban pollution? These types of masks do not work on gas, but do filter the PM2.5 particles which are the primary component of the kind of vog in Kona.

The Hawaii DOH advisory was intended for residents near the eruptions where gaseous SO2 is still present. For areas, like Kona, far away from the eruption, the vog was not considered bad enough to consider a mask. However, the advisory did not include people with breathing problems that might have trouble with the moderate level of vog found in Kona during the eruptions. Pollution masks that can filter PM2.5 should help.

Good pollution masks are certified by the National Institute for Occupational Safety and Health, NIOSH, as N95 or N99. Several brands of NIOSH certified masks are sold on Amazon. N95 masks filter 95% of particles larger that 0.3 um, while N99 filters 99%. PM2.5 are particles smaller than 2.5 um, so there may still be some particles smaller than 0.3 um. These masks may not be completely effective in very high levels of PM2.5. We do not expect dangerously high levels of PM2.5 in Kona.

"Kona" refers the city of Kailua Kona or the region nearby, which could include Waikoloa if the term is used broadly. The Kona air quality monitor is in Kealakekua, which is nine mile south of Kailua Kona. Our condo in Waikoloa is 27 miles north of Kealakekua, so the air there should be better that the Kona AQI readings.

Hula at Pahoa

Pahoa is a small town just a couple of mile away from the lava eruptions in Leilani Estates. Yet it is considered safe since it is off the rift where fissures might form, upslope from the lava flow, and upwind from the SO2 gas emissions. Here is a heartwarming video of Pahoa Elementary School's late celebration of May Day with hula dancing.

Air Quality

The news about air quality from the Big Island seems to get worse every day. The amount of SO2 rises with as lava flow increases. Rock and steam explosions eject ash. Lava falling into the sea creates clouds of laze, a mixture of glass particles and hydrochloric acid. However, these are mostly problems local to the volcanic area because the trade winds typically blows these pollutant out to sea before they get to the more populated areas of the island.

Here is an example when the SO2 was very high due to fresh lava on May 20. Note that the Green air has some SO2, but less than 0.1 ppm, and is considered good. Yellow is moderate air but still considered okay. Orange air is USG, Unhealthy for Sensitive Groups. Red air is considered unhealthy for the general population.

Consider Hilo, which is just 21 miles northwest of Leilani Estates, the source of most of the SO2. Because the trade winds blow from the northeast, Hilo generally has better air than Kona, 71 miles from Leilani Estates. There was one day, May 17, that Hilo got some Orange SO2 air because the trade winds failed. The history of SO2 measurement on the Big Island can found HERE.

The trade winds can wrap around the south point of the island and blow on the southwest coast, Kona and below. However, Kona has only gotten Green SO2 air so far, even on May 17. This is because of the long distance, about 150 miles, in the round about path that the SO2 has to travel to get to Kona. SO2 reacts with water and dust in the air to form sulfate particles. These particles get larger with time. So the dominant air quality concern in Kona is PM2.5, particles smaller than 2.5 um. The current PM2.5 reading on the Big Island can be found HERE. The PM2.5 AQI, Air Quality Index, uses the same color code as SO2 readings.

Vog is a mixture of SO2 and sulfate particles. Even if the vog in Kona is mostly PM2.5, it can still be bad. I have been watching the PM2.5 AQI for Kona since the start of the eruptions. It has mostly been Green or Yellow, but today it is Orange. Nevertheless, it is easier to filter PM2.5 than SO2 which will be the topic for a future post. 

Needless to say, a filter that works on PM2.5 sulfate should also work on ash and glass particles. The filter may not work on hydrochloric gas from laze, but the amount should be minute relative to SO2. The media has reported that the laze plumes could extend 15 miles along the coast. The lava entry point to the ocean is 70 miles from our condo.

The area affected by the Hawaiian volcano

When reporting the Big Island volcano eruptions, the media rarely mentions the relative size of the affected area to the whole island. Here is the latest map from the USGS which shows the affected area.

On the inset on the map above, you can see that the affected area, in pink, is a small portion of the island. Furthermore, there are only two spots in the affected area with volcanic activity, the Kilauea summit and the Leilani Estates, 26 miles apart.

There are no lava eruptions at the Kilauea summit nor are any expected. There used to be a lava lake at the top of the vent at the summit, visible from an overlook and a big tourist attraction. The activity that we now see at the summit is not caused by lava coming up, but by lava draining down the vent.  Falling rocks and steam from ground water have caused all the eruptions we have seen from the summit.  (The definition of "eruption", allows for a steam explosion without lava). The "Big One", often mentioned in the news, is the hypothetical worse case steam explosion, and may have already happened. No lava flow was ever expected to follow the Big One at the summit.

The lack of lava flow from the summit should not be surprising. Most of the Kilauea eruptions have been along its rift. The rift is the red line in the map inset above. The recent 35 year Kilauea eruption came from the Puu Oo vent on the Middle East Rift Zone, 12 miles from the summit. When the 5.0 earthquake happened on May 3, there was huge pink cloud from Puu Oo. This was caused by rock falling down the vent. There was no lava eruption. Lava had already drained down the Puu Oo vent. Its crater floor had collapse on April 30. There is currently no action at Puu Oo.

The lava eruptions are all contained in an area around Leilani Estates on the Lower East Rift Zone. You can see the size of the eruption area in the inset of the map above; it is the small rectangle on the right. There was nothing surprising about the location; it was classified with a the highest hazard level. The homes were cheap and the insurance was very high. The home owners knew the risks.

The larger part of the map above shows the current lava flows and past lava flows from the Lower East Rift Zone in 1840, 1955 and 1960. You can see that the current flow is normal for the area. The current lava flows came in two phases. The flow from 5/3 to 5/18 was from old magma already in the rift and was sluggish. When a rift opened, there was initial lava splattering and stopped soon after. The flow after 5/19 came from the magma drained from the Middle East Rift Zone. It was more fluid and can be expected to spread, but it does not look like it will exceed past eruptions in the area.

When taken by themselves the two events, the steam explosions at the summit and the lava flows in the Lower East Rift Zone, are not unusual. However, the news reports these event together and made no attempt to stop their audience from conflating them. So one could get the impression that a catastrophic lava explosion is imminent at Kilauea that will affect the whole island. Totally wrong.

There is no imminent catastrophe. There are problems next to the summit and near Leilani Estate. We will be far from either location. The Kona Airport, our Waikoloa condos and Auntie's Honokaa house are all far away from either the Kilauea summit or Leilani Estates. The shortest distance is 48 miles from the Kilauea summit to Honokaa. The longest distance is 75 miles from Leilani Estates to the Kona Airport.

But will the distance protect us from the SO2 gas. The short answer is yes, but requires more explanation and will be the topic of the next blog post.

The need for this blog

Our family planned a reunion on the Big Island for the 4th of July week. We put in our reservations long before the Kilauea Volcano area eruptions started on May 3. The news from the main stream media has been absolutely irresponsible, making a problem local to the Kilauea area seem like an imminent catastrophe for the whole island, if not for the whole state.

The older members of our family who grew up in Hawaii, know that the latest eruptions are not a big deal. But some of the younger family members grew up on the mainland and may be frightened by the apocalyptic media coverage. They may know about other volcanic eruptions in the world that were truly catastrophic. They may not be aware that Hawaiian volcanoes are inherently mild and the current eruption is just another episode of increased activity.

There are some real concerns, like air quality, that can easily be handled and will be covered by future posts to this blog. Right now, here is a video which explains why Hawaiian volcanic eruptions are mild.