Color ‘em confused: A guide to accessing and understanding air quality reports online

  • Community members overflow council chambers for an air quality meeting Wednesday at the West Hawaii Civic Center. (Laura Ruminski/West Hawaii Today)

KAILUA-KONA — Combing through the various color-coded air quality monitoring websites that serve Hawaii Island is a bit like rifling through the scattered pieces of the board game “Sorry!”

Yellow, green, red, blue.


In real life, there are more colors involved — orange, black, purple, maroon. And the stakes are a bit higher. What exactly do these colors mean? And what precisely is each website measuring? Sulfur dioxide? Hydrogen sulfide? Particulate matter 2.5 micrometers in diameter or less?

Vog has more than a couple negative side effects, and in the wake of the Kilauea volcano eruption in Puna, air quality has deteriorated in West Hawaii to a point not seen since the Hawaii Department of Health (DOH) installed a permanent air quality monitor in Kailua-Kona roughly a decade ago.

But read the websites wrong or don’t look at enough of them, and maybe the price you pay involves a pair of stinging eyes after a beach day, or a tight chest and a persistent, hacking cough after a 3-mile jog on Ane Keohokalole Highway.

Oops. Sorry!

Residents who were tired of the island’s air quality monitoring functioning like a board game, only with more confusing directions, piled into the West Hawaii Civic Center’s County Council Chambers Wednesday night for a vog forum.

The panel included medical professionals, DOH officials and a presenter from the United States Geological Survey (USGS). The issue of the color-coding system was broached multiple times.

“I’m a little frustrated with the new color chart,” said Julie Klaz, a 10-year Kona resident, who questioned the panel about it. “People are canceling their trips because they can’t read the new meters. … The average person, they want to see a color they know.”

Dr. Bruce Anderson, DOH director, acknowledged the confusion and explained the contradiction exists because Hawaii County uses a coding system separate from the one employed by the U.S. Environmental Protection Agency (EPA).

He added DOH will employ the standardized EPA coding system on state-operated websites moving forward. In the meantime, here’s a brief guide to understanding air quality monitoring in Hawaii via popular internet resources.

Air quality keys

Not only do websites differ in the colors they use to signify air quality in general terms — such as good, moderate, unhealthy, etc. — they also vary by what pollutant they’re actually measuring.

Lisa Young, environmental health specialist with the DOH’s Clean Air Branch, said this is why one website might designate air quality in Kailua-Kona as good, while another might consider it unhealthy., run by the Environmental Protection Agency (EPA), offers air quality information nationwide. It’s a relevant site for West Hawaii because it monitors PM2.5, or particulate matter measuring 2.5 micrometers or less in diameter.

When inhaled, PM2.5 can make its way deep into the lungs, ultimately mingling with the bloodstream and causing harmful health impacts. By the time emissions from Kilauea reach West Hawaii, many have broken down significantly, rendering particulates the most concerning element of vog in the region.

Airnow uses the same color-coding system as DOH’s short-term sulfur dioxide (SO2) advisory website, part of the state’s vog dashboard, which can be found at or by clicking here. This website is less relevant as significant amounts of SO2 don’t typically reach West Hawaii in tact.

On both websites, green means good. Yellow signifies moderate air quality. Orange indicates conditions are unhealthy for sensitive groups. Red is simply unhealthy. Purple equals very unhealthy, and maroon means hazardous.

The contrast between Airnow and DOH’s SO2 advisory website is an example of what Young describes above.

Kailua-Kona, for instance, is often classified as “good” based on SO2 readings from the DOH short-term advisory website, even when PM2.5 readings from the Airnow website indicate the air quality in the area is as bad as it’s been in 10 years.

The website, linked to a company that sells air quality monitors but also offers a map with available readings from several locations around the globe, uses the same color-coding system as the two aforementioned websites.

While reliable, panelists and air quality experts have suggested in the past that the technology PurpleAir utilizes in its products are not as accurate as permanent monitoring stations installed by DOH or temporary stations on loan from the EPA.

The colors listed for classification purposes on Hawaii County’s toxic gas exposure policy website, accessible at or by clicking here, are fewer but broader.

Blue means little or no risk to the healthy, with highly sensitive people affected at lower concentrations.

Orange means sensitive people may be more seriously affected and should consider evacuating the area, while the general public should attempt to limit exposure due to the chance of some minor health problems.

Red means there are severe risks to the entire population that include immediate dangers to health.

An air monitoring viewer tool launched this week by the EPA, accessible at, utilized the county’s color-coding system.

It measures both SO2 and hydrogen sulfide, or H2S, at more than 30 sites across the island, although only two are located in West Hawaii. The website lists health effects and recommends an appropriate public response for each color.

A black dot on the website means the monitor is down.


Also part of the vog dashboard, a model provides vog forecasts accessible at or by clicking here. The website forecasts expected levels of both SO2 and PM2.5 in several areas across the island.

Anderson said more permanent DOH monitoring sites are coming to West Hawaii, particularly to Kona and Waikoloa. The department is optimistic it can begin installation within the next two months.

  1. mikehira June 8, 2018 4:08 am

    There is one more cause of confusion not mentioned in the article above. The vog model on the mkwc website uses a color progression scheme for PM2.5 that looks like AirNow but has different measurement thresholds for some of the colors. On the vog model Yellow starts at 15 ug/m3, while on AirNow Yellow starts at 12 ug/m3. On the vog model Red starts at 65 ug/m3, while on AirNow Red starts at 55 ug/m3.

    The SO2 thresholds for all the Hawaii website seem to match, but are different from the national EPA standard. For example. on the Hawaii website SO2 Red starts at 1.01 ppm, while on the national EPA standard, Red starts at 0.186 ppm. There similar differences for the other colors.

  2. Niel Thomas June 8, 2018 6:48 am

    Can’t WHT make a chart or spreadsheet with the names of each of the services, a link to each of them, what each measures, and their color coding? Presenting this as a narrative is helpful only to a degree; I’m certainly not ready to take a quiz after reading this piece.

    1. Sea San Koa June 8, 2018 7:15 am

      Spot on Neil

      “SO2 don’t typically reach West Hawaii in tact.”
      in tact? or is it intact?
      “…an example of what Young describes above”
      “…as the two aforementioned websites”

      Bad writing.

    2. ypupule June 8, 2018 8:12 am

      You got “brain fog”?

    3. Buds4All June 8, 2018 8:19 am

      Really…have you not seen WHT does not know how to use spellcheck!

  3. Buds4All June 8, 2018 8:24 am

    “Hawaii Department of Health (DOH) installed a permanent air quality monitor in Kailua-Kona roughly a decade ago.” ……………..wonder if this is hooked to the nuclear sirens and that is why they are either not working or jacked up?

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