Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Scientists find 50-year decline in some Los Angeles vehicle-related pollutants

In California’s Los Angeles Basin, levels of some vehicle-related air pollutants have decreased by about 98 percent since the 1960s, even as area residents now burn three times as much gasoline and diesel fuel. Between 2002 and 2010 alone, the concentration of air pollutants called volatile organic compounds (VOCs) dropped by half, according to a new study by NOAA scientists and colleagues.
“The reason is simple: Cars are getting cleaner,” said Carsten Warneke, a NOAA-funded scientist with the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder.

VOCs, primarily emitted from the tailpipes of vehicles, are a key ingredient in the formation of ground-level ozone which, at high levels, can harm people’s lungs and damage crops and other plants.

The magnitude of the drop in VOC levels was surprising, even to researchers who expected some kind of decrease resulting from California’s longtime efforts to control vehicle pollution.

“Even on the most polluted day during a research mission in 2010, we measured half the VOCs we had seen just eight years earlier,” Warneke said. “The difference was amazing.”

The study was published online today in the Journal of Geophysical Research-Atmospheres, a journal of the American Geophysical Union.

The 98 percent drop in VOCs in the last 50 years does not mean that ozone levels have dropped that steeply; the air chemistry that leads from VOCs to ozone is more complex than that. Ozone pollution in the Los Angeles Basin has decreased since the 1960s, but levels still don’t meet ozone standards set by the Environmental Protection Agency.

Requirements for catalytic converters, use of reformulated fuels less prone to evaporate, and improved engine efficiency of new vehicles have all likely contributed to overall declines in vehicle-related pollution, including VOCs.

The improvement in this one measure of air quality in Los Angeles may not surprise many longtime residents, Warneke said. People who lived in the city in the 1960s often couldn’t see nearby mountains through the smog; today, they often can.

For the new study, Warneke and his colleagues evaluated Los Angeles air quality measurements from three sources: NOAA-led research campaigns in 2002 and 2010, which involved extensive aircraft sampling of the atmosphere; datasets from other intensive field campaigns reaching back five decades; and air quality measurements from the California Air Resources Board monitoring sites, which reach back two to three decades.

Overall, VOCs dropped by an average of 7.5 percent per year. “This is essentially the kind of change we would expect, and it is very good to find that it is actually taking place,” Warneke said.

A few specific VOCs, such as propane and ethane, did not drop as quickly. Those chemicals come from sources other than vehicles, such as the use and production of natural gas. Another recent study led by CIRES and NOAA researchers and published online August 4 in Geophysical Research Letters, also an AGU journal, has shown that one VOC, ethanol, is increasing in the atmosphere, consistent with its increasing use in transportation fuels.

Warneke said that he would expect the decrease in emissions of VOCs by cars to continue in Los Angeles, given that engine efficiency continues to improve and older, more polluting vehicles drop out of the fleet of all vehicles on the road.

Notes for Journalists

Journalists and public information officers (PIOs) of educational and scientific institutions who have registered with AGU can download a PDF copy of this paper in press by clicking on this link

Or, you may order a copy of the final paper by emailing your request to Kate Ramsayer at Please provide your name, the name of your media outlet, and your phone number.

Neither the paper nor this press release are under embargo.


Carsten Warneke, Joost A. de Gouw, John S. Holloway and Jeff Peischl: Chemical Sciences Division, NOAA/ESRL, Boulder, CO, USA, and Cooperative Institute for Research in Environmental Sciences (CIRES), Boulder, CO, USA;

Thomas B. Ryerson: Cooperative Institute for Research in Environmental Sciences (CIRES), Boulder, CO, USA;

Elliot Atlas: Marine and Atmospheric Chemistry, RSMAS/University of Miami, Miami, FL, USA;

Don Blake: Chemistry, University of California at Irvine, Irvine, CA, USA;
Michael Trainer and David D. Parrish: Chemical Sciences Division, NOAA/ESRL, Boulder, CO, USA.

Contact information for award winners:

Carsten Warneke, Email:
AGU Contact:
Kate Ramsayer
+1 (202) 777-7524
NOAA Contact:
Katy Human
+1 (303) 497-4747

Kate Ramsayer | American Geophysical Union
Further information:

More articles from Earth Sciences:

nachricht Ice shelf vibrations cause unusual waves in Antarctic atmosphere
25.10.2016 | American Geophysical Union

nachricht Enormous dome in central Andes driven by huge magma body beneath it
25.10.2016 | University of California - Santa Cruz

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Ice shelf vibrations cause unusual waves in Antarctic atmosphere

25.10.2016 | Earth Sciences

Fluorescent holography: Upending the world of biological imaging

25.10.2016 | Power and Electrical Engineering

Etching Microstructures with Lasers

25.10.2016 | Process Engineering

More VideoLinks >>>