by Ben Lieberman
September 15, 2004

Summer is over, and it was a very good one for air quality in New York City.  In fact, 2004 ranks as perhaps the cleanest year on record, and the long-term trends point to further improvements in the years ahead.  

Preliminary data for June through August show that the New York Metropolitan area had only one day in violation of the federal smog standard that has been in effect since 1979.  As recently as the 1980s, the city averaged 20 such bad air days each summer.  Overall, longtime residents have probably never breathed summer air any cleaner than in 2004 - not bad for a city with a still-growing population of 8 million and chronic traffic congestion. 

Luck had something to do with it.  Summer smog is created by two pollutants, nitrogen oxides (NOx) and volatile organic compounds (VOCs), in the presence of sunlight.  Conditions conducive to smog formation—hot, cloudless, stagnant summer days that cook ambient NOx and VOC molecules into smog—were unusually rare for the area over the past three months.  What was bad news for air conditioner sellers was good news for air quality.  

But it wasn’t all luck.  Emissions of NOx and VOCs have declined substantially in recent decades, and continue to go down each year.  Motor vehicles are the single largest source of these smog-forming compounds, and they have gotten significantly cleaner since the 1970s.  Strict federal emission limits for cars and trucks have more than compensated for the area’s population growth and increases in both number of vehicles and total miles traveled.  Area power plants, factories and other businesses have also made a contribution by lowering emissions.

Back in the 1960s, New York was infamous for its lousy air—only Los Angeles had a worse reputation—but the progress since then has been remarkable. 

Of course, good news is no news when it comes to the environment, and the near absence of smog this year received little coverage.  And environmental activists, though quick to loudly bash President Bush over alleged pollution problems, have been silent about the improvements in air quality.

The city’s air is far from perfect.  A newer, far more stringent smog standard took effect this year, and New York does not presently meet it.  But air quality will continue to get better.  New federal regulations, to be phased in over the next few years, demand even greater reductions in smog-forming compounds from cars, SUVs, and trucks.  No additional measures need be imposed to achieve these improvements, just the inevitable turnover from older and dirtier vehicles to cleaner new ones.   Tougher new utility emissions standards, one of which took effect this year, will also help bring down pollution levels.   

Over time, we will see less and less summer smog, regardless of the weather.  The unusually clean air over the past three months will become typical of future New York summers.