The most striking visual on the page was a graph that showed the comparative emissions across several types of vehicles. Here are the numbers from the table but without the visual impact of the chart:
Nitrogen Oxide Emissions in grams/mile:
Light-duty hybrid (Prius, Civic hybrid) 0.02
Passenger car (Camry, Accord, Malibu) 0.10
Light-duty truck 2 (Cherokee, Caravan, Sienna) 0.30
Light-duty truck 4 (F-150, Sequoia, Land Rover) 0.60
Heavy-duty truck (Hummer, RVs) 0.90
This table makes it clear that increasing the fleet of hybrid vehicles in our area, particularly if they are replacing other vehicles, would make a big dent in our air quality problems. In fact, DC is doing well with hybrid ownership, double the national average (link). Much of this has been driven by the HOV exemption for clean vehicles, prompting some drivers to invest in hybrids in order to be able to drive on the HOV lanes. This year, also, Arlington County has introduced a tax break for people to buy hybrid vehicles.
These seem like good policies as we strive to improve regional air quality. There has been controversy about whether the clean-vehicle exemption for HOV should be terminated. I think this information supports the position to keep it in place, since 3 single-occupant Priuses only emit 60% or less emissions than a car (or worse, an SUV or minivan) with three passengers. Some parties believe the exemption should end, because too many single-occupant vehicles will clog the carpool lanes. I will only be convinced after much more aggressive efforts, including much higher fines, are taken to eliminate the HOV violators, who I see all the time on I-66.
Keep in mind that owners of these vehicles are contributing to better air quality with 100% of the miles they drive, even though only 15% - 50% of their driving might be on HOV lanes, so it is in the interest of all who want cleaner air to encourage more purchasing of cleaner cars.
(In the interest of disclosure, I own a Toyota Camry hybrid, but do not have the requisite license plates to drive in the HOV lanes. I also have a personal interest in improving air quality, because my daughter suffers from asthma.)