Some Air Pollutants Plunge 98% in L.A.

The concentration of volatile organic compounds (VOCs) in the air in the Los Angeles Basin has dropped to about 2 parts per billion from 100 ppb in 1960, according to research by the National Oceanic and Atmospheric Adminstration.

Most VOCs come from vehicles. Their dramatic decline an average 7.5% per year over five decades has come as gasoline consumption in the region nearly tripled to 364 million barrels per year.

"The reason is simple: Cars are getting cleaner," explains researcher Carsten Warneke. He reports that VOC levels in 2010 even on high-pollution days were half what they were eight years earlier, an improvement he describes as "amazing."

The scientists attribute the improvement to better vehicle fuel economy, the use of catalytic converters to remove VOCs from exhaust and reformulated fuels that resist evaporation. NOAA's findings were published this week in the Journal of Geophysical Research.

VOCs are a key ingredient in the formation of ground-level ozone. At high levels, ozone can harm lungs and plant life. The researchers say ozone levels in Los Angeles also have declined in the past 50 years but still don't meet standards set by the U.S. Environmental Protection Agency.