The May 23 Close to Home piece "Buses That Give Us Breathing Room" ignored some of the facts in the debate about whether Metro should build a compressed natural gas (CNG) fueling facility in Maryland and buy 200 CNG buses.

The Sierra Club and some elected Metro board officials want to pursue this strategy in the name of clean air, but Metro has a better alternative for both its bus riders and the environment. This alternative would cost the same amount of money as the CNG plan while improving air quality and allowing Prince George's County to have its fair share of new, more reliable buses.

CNG is expensive. During the next four fiscal years, Metro has budgeted $111 million for 200 CNG buses and a retrofitting of one of its garages to serve as a CNG fueling facility. The fueling facility, estimated to cost $20 million to construct, is expected to cost about $1 million a year to operate. With that same money, Metro could buy 246 new buses -- 196 clean diesel buses and 50 diesel-electric hybrids.

Forward-looking transit agencies around the country are buying hybrids, which run partially on electric power and thus have lower fuel consumption, costs and emissions. New York City, for example, has ordered 335 hybrids. As Metro gains experience with operating hybrid buses and the price comes down, it can add to its initial fleet of 50.

Buying 246 diesel and hybrid replacement buses instead of just 200 CNG buses means that the Metrobus fleet will produce fewer emissions because it will be able to retire more of its older buses. The head of the Metropolitan Council of Governments' air quality division has testified that one of the most effective things Metro can do to improve air quality is to get its older buses off the street. One aging diesel bus can emit as much nitrogen oxide and volatile organic compounds -- the pollutants that contribute to unhealthy air quality in the summer -- as three of the diesel buses sold today. As dramatic as those numbers sound, Metro's bus fleet nonetheless has a less than 1 percent effect on the region's air quality.

Both Maryland counties served by Metro also could benefit from the new diesel buses. CNG buses require a special fueling facility and so must operate primarily in the area surrounding that facility. Only one CNG fueling center is budgeted for Maryland, to be located in Montgomery County. That would leave Prince George's County mostly with aging diesel buses (average age, 12 years) for the next four years.

Metro now has more than $1.5 billion in unmet capital needs. To justify asking its riders, its regional governments and Congress for additional funding, it must demonstrate common sense in spending the money that it already has. That means buying new diesel and hybrid buses, not CNG buses. The bottom line is that more new buses are better than fewer new buses -- especially when the result still is cleaner air.

-- Robert Smith

chairs the board of the Washington Metropolitan Area Transit Authority.