By Joe Schoenmann (contact)

Sun, Aug 17, 2008 (2 a.m.)

Decades ago, the intersection of Charleston Boulevard and Fremont Street was infamous — to air quality experts. It was known for having the valley’s highest concentration of poisonous carbon monoxide during the winter. Not high enough to breathe for a bit and keel over, but higher than air quality people like to see.

In 1990 an amendment to the Clean Air Act required communities to do something to correct poor air pockets such as the one at Charleston and Fremont.

Clark County responded over many years, and the air has become cleaner.

At Tuesday’s Clark County Commission meeting, air quality control experts will tell commissioners that they want to ask the Environmental Protection Agency to formally recognize Clark County for reaching federal standards for carbon monoxide.

It’s good news, but we’re not out of the woods yet.

Q: How bad was our carbon monoxide?

The federal government set a standard of 9 parts per billion, but the Las Vegas Valley was hitting 11 parts per billion on about 40 days of the year in the 1980s, said Dennis Ransel, planning manager for the Department of Air Quality Management. Since 1998, the county has not exceeded the federal standards. Said Ransel: “The trend is continuing downward and is currently less than 5 (parts per billion).”

What has the county done to lower carbon monoxide?

Largely, more stringent smog checks. In 1996, the county started requiring smog tests using vehicles’ onboard diagnostic computers. Before then, tests were done on tailpipe exhaust, which isn’t as accurate or predictive. “We have a higher failure rate,” Ransel said, which means more polluting cars are being detected. “In some cases, we’re catching problems before they become problems.”

The county also demands that gasoline sold here create less potentially polluting vapor. In fact, our fuel volatility is lower than that of gas sold in California. Ransel says that could change. We could soon start using the same kind of gasoline as California.

Why change if it is working?

In order to keep the fuel blend, we have to show that we need it,” Ransel said. “Refineries don’t like using our standard, because it results in less gasoline per barrel of oil. The more important issue is supply. It improves the reliability of supply, which becomes a factor when the (supply) pipes from California break.”

If Clark County can use the same gas blend as nearby states, Ransel said, gasoline could be trucked to Las Vegas from those states.

Will our gas cost less then?

We certainly won’t see an increase and maybe a slight decrease, Ransel said.

But isn’t gas in California is more expensive?

That’s because gasoline taxes are higher than in Nevada.

We’re free and clear, air-wise?

Not quite. We still have a big problem with ozone. Ozone high in the stratosphere is good; it blocks harmful ultraviolet rays. At ground level, however, ozone can aggravate lung ailments. Though the county met old ozone standards, the EPA issued a new ozone standard this year. Ransel said Clark County and about 300 other counties nationwide do not meet that standard.

When will it be met?

The target is 2013.

Where can I find information on air quality in the valley?

For a look at daily ozone levels, see www.accessclarkcounty.com/depts/daqem/aq/pages/monitor_index.aspx.