When first-time visitors arriving in Hawaii by air begin their final decent toward the Kailua-Kona airport on the Big Island, they are usually struck by two things. First, the rock graffiti (white rocks arranged in words and phrases on black lava) gets a few marvels. It is truly a neat surprise from the air.

Second, tourists might be stunned by what appears (on windless days) to be air pollution equal to Los Angeles or Houston. However, it's not what you think: Curiously, it's volcanic smog, or "vog."

An island that is home to an active volcano that continually spews subterranean gases sometimes accumulates the murky haze. Although trade winds generally keep the vog hanging over the western cost of the Big Island, it can sometimes show up in other parts of the state, like Maui or even Oahu. the stuff occurs when the volcanic gases come into contact and react with sunlight.

Although the vog, like smog, can trigger health problems such as asthma, the Hawaiian version of air pollution is a naturally occurring substance. Therefore, there's no point in blaming cars for its presence.

Thus, at this point in time there are no set emissions standards for vehicles in Hawaii. At the same time, the state is on the frontlines of the electric vehicle movement and has a praiseworthy number of hybrids on the streets.

Other than the vog, Hawaii's breezy location in the middle of the Pacific and the rather small population keeps the air quality in relatively good shape. As a matter of fact, Honolulu consistently ranks as one of the cities with the least ozone air pollution.

Plus, with the massive number of scooters and mopeds about, residents tend to be on the low-emissions side in many cases anyway. And gas prices are so elevated that many people simply buy efficient (and by correlation, low-emissions) vehicles out of necessity.

So for now, you need to only get a safety inspection to register your car―you can skip the emissions test.

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