In L.A., Pollution is Down Dramatically but Bad Air Remains

A new study by NOAA scientists and colleagues shows a stunning reduction in vehicle-related air pollutants in the Los Angeles basin over the past several decades. Despite the gains, unhealthy air remains.

1 minute read

August 20, 2012, 8:00 AM PDT

By Jonathan Nettler @nettsj


The recent paper, published in the Journal of Geophysical Research, shows a dramatic 98 percent drop in air pollution from motor vehicles since the 1960s, despite a threefold increase in the use of gasoline and diesel fuel over the same period. The chemicals tracked by the researchers, called volatile organic compounds (VOCs), are primarily emitted from the tailpipes of vehicles, and "are a key
ingredient in the formation of ground-level ozone," writes the National Oceanic and Atmospheric Administration. 

"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," said Carsten Warneke, Ph.D., a NOAA-funded scientist with the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder. "The difference was amazing."

Despite the improvements in vehicle emissions, attributed to "requirements for catalytic converters, use of reformulated fuels less
prone to evaporate, and improved engine efficiency of new vehicles," overall ozone levels in L.A. have not fallen as steeply. "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."

Thursday, August 9, 2012 in NOAA

Aerial view of Eugene, Oregon at dusk with mountains in background.

Eugene Ends Parking Minimums

In a move that complies with a state law aimed at reducing transportation emissions, Eugene amended its parking rules to eliminate minimum requirements and set maximum parking lot sizes.

December 3, 2023 - NBC 16

Green Paris Texas city limit sign with population.

How Paris, Texas Became a ‘Unicorn’ for Rural Transit

A robust coalition of advocates in the town of 25,000 brought together the funding and resources to launch a popular bus service that some residents see as a mobility lifeline—and a social club.

November 30, 2023 - Texas Monthly

SMall backyard cottage ADU in San Diego, California.

San Diegans at Odds Over ‘Granny Towers’

A provision in the city’s ADU ordinance allows developers to build an essentially unlimited number of units on single-family lots.

November 29, 2023 - CALmatters

Aerial view of downtown Salt Lake City, Utah with snow-capped mountains in background.

How Salt Lake City Maintained a Vibrant Downtown

Unlike other major cities, the Utah capital’s downtown has seen a steady stream of visitors even as demand for office space diminishes.

December 8 - Governing

White modular home being installed on a lot.

Modular Homes Make Housing More Affordable in Chicago

Cheaper and faster to construct, modular homes provide an affordable alternative to traditional new construction for low- and moderate-income residents on Chicago’s South Side.

December 8 - WTTW

Woman bus driver sitting behind wheel of bus wearing long-sleeved shirt and yellow safety vest.

How Inequality Impacts Transit Safety

Transit workers are being assaulted by riders at alarming rates, and inequity may be partly to blame.

December 8 - Streetsblog USA

News from HUD User

HUD's Office of Policy Development and Research

New Updates on PD&R Edge

HUD's Office of Policy Development and Research

"Rethinking Commuter Rail" podcast & Intercity Bus E-News

Chaddick Institute at DePaul University

Urban Design for Planners 1: Software Tools

This six-course series explores essential urban design concepts using open source software and equips planners with the tools they need to participate fully in the urban design process.

Planning for Universal Design

Learn the tools for implementing Universal Design in planning regulations.