How to find the AQI of Waikoloa

If you googled AQI for Waikoloa, you may get to the Weather Underground for Waikoloa webpage. It will show you an AQI for PM2.5 and claims its source is EPA AirNow. If you go to the AirNow for Hawaii webpage, you will see that there are only five AQI PM2.5 monitoring stations on the Big Island. The closest station to Waikoloa is Kona. You will see that the Weather Underground AQI for Waikoloa is identical to the AirNow AQI for Kona. So when you google the AQI for Waikoloa, you are actually getting the AQI for Kona.

Under normal wind conditions, the emissions from Kilauea are blown south out to sea but wrap around to the southwest coast. The AQI for PM2.5 on the southwest coast is typically worst that the rest of the island, even for places closer to Kilauea. Waikoloa is on the the northwest coast, 27 miles north of Kona, and should have better air quality, but there are no EPA stations above Kona to confirm this.

However, there is a private AQI network, called Purple Air which sells cheap PM2.5 monitors and makes the readings from their customers available on the internet. There are several Purple Air monitors spread across the island, one in Waikoloa and many around Kona. The readings from the Kona monitors show that the Purple Air monitors are consistent among themselves. When the Kona monitors are compared to the Waikoloa monitor, it shows that the air in Waikoloa is much better than in Kona on a day with typical trade winds. But on days that the trade winds fail, the AQI readings in Waikoloa is about the same as in Kona. The reading below was taken on 6/10/18 had typical trade winds.

Note that the Purple Air monitor in near to the AirNow Kona station does not agree with the official AQI reading. Also the Purple Air monitor in Waikoloa sometimes behave erratically.