2, 4, 6.

If you live in NYC, you probably live in a building running one of these fuel classes for heating.

Nos. 4 and 6 are why are children under fourteen in NYC have double the asthma rate of the national average and why on some days you feel like a smoker even though you quit back in 1999. More pollution comes from burning heating fuel than all cars and trucks combined.

9000 buildings in the city still subscribe to 4 and 6 fuels, described unappetizingly as "unrefined sludge" by the Environmental Defense Fund in its recent and ominously titled report The Bottom of the Barrel: How the Dirtiest Heating Oil Pollutes Our Air and Harms Our Health. This posse of 9000, which counts ritzy communities like the storied Dakota among its membership, creates 87 percent of the soot pollution arising from heating oil. New Yorkers burn more than one billion gallons of the stuff each year, more than any other US city. Last week, the City Council voted to improve the quality of heating oil by reducing the sulfur limits in No. 4 and requiring a minimum of 2% biodiesel in home heating oil. Last month, the State passed a law to reduce the sulfur content  of No. 2 heating oil by 99%, to go into effect in 2012. No. 2 represents around 70% of all the heating oil used in the city and have 15 times less the pollution of No.6 oils. Changing the types of oil we use can improve air quality, save on maintaining our heating systems and boost our energy security by reducing our dependence on foreign oil. Natural gas is a cleaner alternative, as are renewable energy sources.

The City Council's press conference was held at Metro Biofuels in Brooklyn, one of the largest biodiesel manufacturers in the area. Biodiesel, made from a wide variety of vegetable or plant oils including used restaurant grease, is not only renewable, but also a surprisingly easy sell. NYDesigns resident Paul Miller lead his Upper East Side pre-war co-op through a changeover from No.6 to a biofuel/No.6 blend, with the goal of switching over to a No. 4 blend by this winter.

"It cost us nothing," he shared. "We used the same tanks, burners and boilers and the 2% blend acts as a cleaning agent, resulting in an immediate improvement in efficiency and longer intervals between service visits." The available conversion tax rebate stands at $0.01/gallon for each percent of biodiesel, and Paul thinks more incentives are on the horizon. "Everyone at 308 has been happy with the reduction of toxic products in the building, particularly parents. Our conversion to biofuel went off without a hitch without any additional costs."