For the past few months I have been pouring through a huge amount of US and China air quality management regulations, policies, research papers, and news articles. Here are a few major takeaways from what I’ve learned so far about air pollution control:

  • There are many kinds of air pollutants. Each pollutant behaves differently in the atmosphere; requires it’s own special control strategy; affects multiple regions, industries, and regulatory bodies; and harms millions of people every year - particularly the young and elderly.
  • There are many kinds of emissions sources (cars, power plants, your old couch). Vehicles are the most difficult to control because once they are in-use there are very limited strategies to reduce emissions.
  • Air pollution is especially fierce in rapidly developing countries like China and India.
  • These countries can learn from the US, which has over half a century of experience tackling air pollution.
  • California, particularly in Los Angeles, has been at the forefront of air pollution control since it’s population began rapidly increasing in the early twentieth century.

In the hope that history repeats itself as little as necessary, I’ve compiled a timeline of California and Los Angeles’ air quality management from web articles by the Environmental Protection Agency (EPA), California Air Resources Board (CARB), and South Coast Air Quality Mangement District (SCAQMD).

Early 20th Century

Los Angeles suffered from smog well before World War II. Industrial smoke and fumes were so thick during one day in 1903 that residents mistook it for an eclipse of the sun. From 1905 to 1912, the Los Angeles City Council adopted several primitive measures to combat dense smoke emissions.


First recognized episodes of smog occur in Los Angeles in the summer of 1943. In October 1943, the Los Angeles County Board of Supervisors appointed a Smoke and Fumes Commission to study the problem.


LA County supervisors in February 1945 banned emissions of dense smoke and established an office of Director of Air Pollution Control. The City of Los Angeles began its air pollution control program, establishing the Bureau of Smoke Control in its health department. Other cities had yet to follow.


Raymond R.Tucker studies the Los Angeles area’s smog problem and recommends creating a powerful county-wide air pollution agency with broad powers to adopt and enforce air pollution regulations.


On Oct. 14, 1947, supervisors activated the Los Angeles County Air Pollution Control District, the first in the nation, and appointed Louis C. McCabe as its director. On Dec. 30, 1947, the district put teeth into its air quality program by requiring all major industries to have air pollution permits.


Arie J. Haagen-Smit, a chemistry professor at the California Institute of Technology in Pasadena, started examining plants that had been damaged by smog. Farmers near Southland refineries complained that air pollution damaged their crops, bleaching or discoloring the leaves of plants.


More than 100 electric transit systems were replaced with buses in 45 US cities, including Los Angeles.

County supervisors activated air pollution control districts (APCDs) in Orange County. Haagen-Smit discovers that ozone is a key air pollutant. By exposing plants to ozone in sealed chambers, he showed they suffered similar symptoms as those damaged by smog. Haaggen-Smit also demonstrated in the early 1950s that ozone caused eye irritation, respiratory problems and damage to materials.


After analyzing the contents and using them to create artificial “Haagen-smog” in the laboratory, Haagen-Smit announced in 1952 that ozone, the primary ingredient in smog, was not directly emitted from tailpipes or smokestacks, but was created in the atmosphere.

In London in December 1952, a killer smog so thick that residents could see no more than three feet claimed 4,000 lives. Fearing a similar catastrophe in Los Angeles, Gov. Goodwin J. Knight appointed Arnold O. Beckman of Beckman Instruments to chair a committee recommending air pollution reforms.

One year later, the Beckman Committee made several far-reaching recommendations that set the air pollution agenda for years to come. The committee recommended that:

  • Hydrocarbon emissions be reduced by cutting vapor leaks from refineries and fueling operations;
  • Automobile exhaust standards be established;
  • Diesel trucks and buses burn propane instead of diesel;
  • Heavily polluting industries consider slowing their growth;
  • Open burning of trash be banned; and
  • A rapid transit system be developed.


Los Angeles County started “Smoke School Program” for black smoke, beginning the standardization of “Visible Emission Programs” nationwide.

Los Angeles APCD started requiring controls to reduce hydrocarbon emissions from industrial gasoline storage tanks, thereby reducing 460 tons of smog-forming emissions per day. Subsequent rules reduced hydrocarbon emissions from filling gasoline tank trucks and underground storage tanks at service stations.


Los Angeles County Motor Vehicle Pollution Control laboratory began within the Los Angeles APCD.


Interstate Highway Act of 1956 passed, paving the way for increased highway construction.


Riverside and San Bernardino counties activate air pollution control districts.


More than a decade after the problem was first identified, trash collection programs were established and backyard incinerators were finally banned.


The first statewide air quality standards were set by the Department of Public Health for total suspended particulates, photochemical oxidants, sulfur dioxide, nitrogen dioxide, and carbon monoxide


Reliable measurements of ozone concentrations began to be recorded.


The California Air Resources Board (CARB) was formally established under California’s EPA to coordinate efforts among the various air pollution management districts. It was created from the merging of the California Motor Vehicle Pollution Control Board and the Bureau of Air Sanitation and its Laboratory.

Federal Air Quality Act of 1967 was enacted. It established a framework for defining “air quality control regions” based on meteorological and topographical factors of air pollution. It allowed the State of California a waiver to set and enforce its own emissions standards for new vehicles based on California’s unique need for more stringent controls.


The SCAQMD’s maximum one-hour ozone concentration recorded was 0.58 ppm, nearly five times greater than the health-based national standard of <0.12 ppm that would be adopted in 1971.


The SCAQMD’s maximum one-hour ozone concentration recorded was 0.39 ppm. The area exceeded Stage 1 smog alerts (0.20 ppm) on 118 days.

Air quality officials in the four counties formed a short-lived, voluntary regional agency called the Southern California Air Pollution Control District. The agency’s fatal flaw was that any county could withdraw at any time, sabotaging a regional control effort.


The South Coast Air Quality Management District was formed. It included portions of Los Angeles, Orange, Riverside and San Bernardino counties.

The Legislature twice passed bills to create a mandatory regional agency, and former Gov. Ronald Reagan vetoed them both. Finally, former Gov. Jerry Brown, making good on a campaign promise, signed Assembly Bill 250 on July 2, 1976, creating the South Coast Air Quality Management District. The law and the AQMD became effective on Jan. 1, 1977.


Air quality officials required cumbersome sleeves on gasoline fuel pump nozzles to keep hydrocarbon gases from escaping when motorists filled up at service stations.

Late 1970s

The City of Los Angeles and later the state required vehicle inspections to ensure that pollution control equipment was operating properly and hadn’t been tampered. This controversial inspection and maintenance law evolved into today’s SmogCheck program, administered by the state Bureau of Automotive Repair.


The Smog Check program was enacted by CARB to ensure the proper maintenance of vehicle emissions control technology.


The SCAQMD’s maximum one-hour ozone concentration recorded is 0.39 ppm. The area exceeded Stage 1 Smog Alerts (0.20 ppm ozone) on 83 days this year, an improvement of 19 days since 1980.


James M. Lents, former director of clean air efforts for the State of Colorado, took the helm at SCAQMD.


SCAQMD’s Governing Board adopted a landmark rideshare program in 1987. It required employers with more than 100 employees to offer tangible incentives to employees to carpool and ride public transit to work. For eight years, the program achieved marked success, reducing 272,000 trips per day.


SCAQMD established its Technology Advancement Office to help private industry speed up the development of low- and zero-emission technologies.


Lents directed the development of the agency’s first Air Quality Management Plan to lay out a step-by-step blueprint identifying the specific control measures needed to attain clean air standards by 2007. AQMD’s Governing Board adopted it in 1989, creating headlines across the nation and in Europe.

The plan was the first to call for a number of advanced technologies, including zero-emission electric vehicles, and to specify that clean air could not be achieved in the Southland without them.

One example of regulation fostered by SCAQMD’s plan was CARB’s landmark Low-Emission/Zero-Emission Vehicle mandate, which has achieved the development and commercialization of alternate-fueled and electric vehicles.

Late 1980s

SCAQMD also adopted measures in the late 1980s to control specific toxic pollutants, such as hexavalent chromium and asbestos, as well as chlorofluorocarbons known to destroy the Earth’s stratospheric ozone layer.


The SCAQMD’s maximum one-hour ozone concentration recorded is 0.33 ppm. The area exceeded Stage 1 Smog Alerts (0.20 ppm ozone) on 42 days this year, an improvement of 41 days since 1985.

SCAQMD established an Ethnic Community Advisory Council to advise on the impact of air quality in ethnic communities.


SCAQMD adopted its Regional Clean Air Incentives Market (RECLAIM) program. The program includes about 330 of the largest emitters of nitrogen oxides and sulfur oxides, combustion byproducts that form ozone and particulate pollution. Rather than regulating each polluting piece of equipment and specifying the exact kind of pollution control technology required, RECLAIM imposes an overall emissions limit on each facility. The limit declines each year, so that by 2003, the facilities in sum will have reduced 77 tons of nitrogen oxide emissions and 16 tons of sulfur oxides per day. The business is free to reduce emissions any way it wishes, giving it the flexibility to choose the most cost-effective method. If a facility reduces its emissions below its limit in a given year, it earns RECLAIM trading credits that can be sold to a facility unable or unwilling to make the changes necessary to meet its target that year. As of early 1997, more than $30 million in RECLAIM credits had been sold, and the program’s emission reduction targets were being met.


SCAQMD refocused its rideshare program’s emphasis from carpooling to a broader goal of reducing vehicle emissions.


Legislature required SCAQMD to phase out its mandatory program, if voluntary ridesharing shows equivalent emission reductions.


The SCAQMD’s maximum one-hour ozone concentration recorded is 0.24 pm, 59% improvement from 1965. The area exceeded Stage 1 Smog Alerts (0.20 ppm ozone) on 7 days this year. This is an improvement of 111 days or a 94% reduction as compared to 1975.


The Governing Board developed a follow-up plan with an additional set of initiatives which became the Children’s Air Quality Agenda.


The South Coast Air Quality Management District’s maximum one-hour ozone concentration recorded is 0.18 parts per million. The area has no Stage 1 Smog Alerts (0.20 ppm ozone) this year, down from 42 Alerts in 1990.

Adoption of an Air Toxics Control Plan examining the overall direction of the SCAQMD’s air toxics control program over the course of the next decade.


Began providing substantial incentives to public school districts to purchase new very clean CNG buses and low-emitting diesel buses under the Lower Emission School Bus Program.

New statewide standards were passed to reduce diesel soot and smog forming emissions by 90% from new large diesel engines. The new standards take effect with the 2007 model year and affect engines that power big rig trucks, trash trucks, delivery vans, and other large vehicles.


The nation’s first strategy for reducing Cumulative Impacts, or combined sources, of air pollution in the region is formulated.


Electric vehicle buyers were offered an opportunity to take advantage of new purchase incentives of $9,000 under guidelines approved by the California Air Resources Board for the Zero Emission Vehicle Incentive Program.

CARB adopted Heavy Duty Diesel Trucks idling controls. The regulation required Heavy Duty Diesel Trucks and interstate bus operators to shut their engines down after five minutes of non-essential idling. The regulation affected more than 400,000 trucks and buses registered in CA and all out-of-state trucks and buses operating in CA.


AB 32, the California Global Warming Solutions Act of 2006, is signed into law. It establishes the first-in-the-world comprehensive program of regulatory and market mechanisms to achieve real, quantifiable, cost-effective reductions in greenhouse gases (GHG). It makes CARB responsible for monitoring and reducing GHG emissions.


The ports of Long Beach and Los Angeles, in cooperation with the United States Environmental Protection Agency, CARB, and SCAQMD, developed the most comprehensive plan in the US seaport history to reduce air pollution and associated health risks generated from port-related operations.

California switched to ultra-low sulfur diesel fuel.


CARB approved the South Coast and San Joaquin Valley Air Quality Management Districts’ strategies to improve air quality in their regions.

Shore power regulations require operators of certain types of ocean-going vessels to shut down their diesel auxiliary engines and hook up to shore power while docked at the state’s busiest ports.


Heavy duty diesel truck replacement was implemented by the SCAQMD through Goods Movement Emission Reduction Funding Program (Proposition 1B) funds.

CARB adopts two critical regulations aimed at cleaning up harmful emissions from the estimated one million heavy-duty diesel trucks. One requires installation of diesel exhaust filters or engine replacement and the other requires installation of fuel efficient tires and aerodynamic devices.

CARB receives an additional $48 million from AB 118 to comply with regulations aimed at cleaning up diesel emissions from an estimated 420,000 trucks and buses. These funds will help truckers pay for the engine retrofits, replacements, and other fuel efficient equipment.


May 1, 2009 - the Governing Board restructured the Ethnic Community Advisory Council into the Environmental Justice Advisory Group (EJAG).


Implementation of the Clean Communities Plan (CCP) to reduce the exposure to air toxics and air-related nuisances throughout the district, with an emphasis on cumulative impacts.


SCAQMD releases the 2012 Air Quality Management Plan for the next three years. Measures include:

  • Basin-wide Short-term PM2.5 Measures
  • 8-hour Ozone Measures
  • Transportation Control Measures

Many of the control measures proposed are not regulatory in form, but instead focus on incentives, outreach, and education to bring about emissions reductions through voluntary participation and behavioral changes needed to complement regulations.


The latest 2016 Air Quality Management Plan is currently in development, and will focus on bringing ozone and PM2.5 to acceptable levels.

Today’s most significant air quality challenge in the Basin is to reduce oxides of Nitrogen (NOx) emissions, a precursor of ozone and particulate matter, sufficiently to meet the upcoming standard deadlines. This involves an additional 50% reduction in NOx by 2023, and an additional 15% NOx reduction beyond 2023 levels by 2031.

The primary challenge is that mobile sources currently contribute about 88% of the region’s total NOx emissions, and SCAQMD has limited authority to regulate mobile sources. SCAQMD is working closely with the California Air Resources Board and U.S. EPA, which have primary authority over mobile sources to ensure mobile sources do their fair share of pollution reduction.