"VOG" is Volcanic Air Pollution. Oahu experiences "VOG" when trade winds change direction after there has been volcanic action on the island of Hawaii or otherwise known as the Big Island. The winds will blow this volcanic air pollution towards us and make our little world look all hazy.
Following are pictures I took today from down the street from where I live in Waipio Gentry on the island of Oahu and viewing the downtown Honolulu area. In the far background is Diamond Head and usually there is an unobstructed view with blue clear skies.

View from "Cliffside Villages" to Pearl Harbor to Downtown Honolulu!
View on left taken 2 hours later from the park by my house View on right is at the Central Oahu Regional Park


For more information on Vog.....Click here for Vog Index and
Current Vog Conditions 
May 18, 2007 News story on Lava delta lost 23 acres in latest collapse (a chunk of Kileauea Volcano on the Big Island crashed into the ocean. Quote: Scientists at the U.S. Geological Survey's Hawaiian Volcano Observatory had originally estimated the May 10 lava delta collapse at East Lae'apuki at 16 acres, but now say it's closer to 23. Also, new cracks in the lava delta have been observed, hinting at further collapses.
Courtesy of USGS Hawaiian Volcano Observatory Check out the crack!
Other Interesting Info:
Visitor and Newcomer Safety Tips for Hawaii!
HAWAIIAN Spirits and Superstitions