Facts Not Fear on Air Pollution

Policy Reports | Energy and Natural Resources

No. 294
Monday, December 11, 2006
by Joel Schwartz

Myth No. 1: Air Quality Is Bad and Getting Worse

Air pollution has been declining for decades across the United States.  Since the passage of the Clean Air Act in 1970, the U.S. Environmental Protection Agency (EPA) has been the federal agency charged with monitoring and regulating emissions of air pollutants.  Trends for the monitored concentrations of some regulated pollutants are displayed in Figure I.  [Also see the Appendix Table.]1  Note the large improvements for all of them.  Between 1980 and 2005:

  • Fine particulate matter (PM2.5) declined 40 percent.
  • Peak 8-hour ozone (O3) levels declined 20 percent, and days per year exceeding the 8-hour ozone standard fell 79 percent.
  • The improvement was even greater for the older, less stringent 1-hour ozone standard; peak levels dropped 28 percent and exceedances days dropped 94 percent.
  • Nitrogen dioxide (NO2) concentrations in air dropped 37 percent while sulfur dioxide (SO2) decreased 63 percent; carbon monoxide (CO) levels dropped 74 percent; and lead declined 96 percent.
Reduction in Air Pollution Concentrations

"Levels of regulated pollutants in the air have fallen dramatically."

Not all pollutants have been tracked since 1980.  Those that have only been monitored more recently are also declining.  For instance:

  • Specific components of particulate matter are also declining; for example, sulfate particulates formed from sulfur dioxide (SO2) emissions, most of which comes from burning coal for electricity, declined 32 percent from 1989 to 2004.2 
  • EPA also recently reported that larger particulate matter - less than 10 microns in diameter (PM10) - dropped 25 percent between 1990 and 2005.

As Figure II shows, total emissions also improved dramatically. Between 1980 and 2005:

  • Oxides of nitrogen (NOx) emissions decreased 30 percent and SO2 dropped 42 percent;
  • Emissions of volatile organic compounds (VOCs), which are a variety of compounds regulated as pollutants, fell 47 percent;
  • CO emissions were reduced by 50 percent; and
  • Lead dropped 96 percent.
Figure II - Reduction in Total Emissions

"Emissions of regulated pollutants have also fallen."


Meeting Federal Standards.  These large pollution reductions have significantly improved compliance with federal air pollution standards for metropolitan areas:

  • Virtually the entire nation meets federal standards for CO, NO2, SO2 and lead.3
  • The nation is also near full compliance with the 1-hour standard for ozone and soot (PM10).

Compliance has also greatly improved for the more stringent ozone and soot standards EPA adopted in 1997: 

  • About 75 percent of the nation's ozone monitors violated the 8-hour ozone standard in 1980, but the violation rate was 18 percent at the end of 2005.4
  • About 90 percent of monitoring locations violated federal PM2.5 standards in 1980, compared to only 16 percent by the end of 2005.5

"Remarkably, pollution fell while energy use rose, automobile travel increased and the economy grew."

These pollution reductions translate into corresponding decreases in the fraction of Americans living in areas that violate federal air pollution health standards.

Figure III - Transportion%2C Energy and Economic Growth

Air Pollution, Transportation and Economic Growth.  What makes these air quality improvements so extraordinary is that they occurred during a period of increasing motor vehicle use, energy production and economic growth.  As Figure III shows, between 1980 and 2005:

  • Miles driven each year nearly doubled for automobiles (93 percent), while diesel truck miles more than doubled (112 percent).
  • Tons of coal burned for electricity production increased 61 percent.
  • The dollar value of goods and services (gross domestic product or GDP) more than doubled (114 percent). 

Nevertheless, air pollution of all kinds sharply declined because of cleaner motor vehicles, power plants, factories, home appliances and consumer products.

Automobile and Diesel Truck Emissions.  On-road measurements of emissions from cars and diesel trucks show rapid improvements:

  • In Pennsylvania tunnels, emissions from the average diesel truck declined 83 percent from 1973 to 19996 and in a San Francisco Bay Area tunnel, emissions from the average diesel truck declined at least 50 percent between 1997 and 2004.7
  • Emissions data collected on the road and in automobile inspection programs in several cities show that average automobile emissions are declining about 10 percent per year as the fleet turns over to inherently cleaner automobiles and older models head for the scrap heap.8

"Emissions from SUVs, pickups and diesel trucks will continue to decline."

Pollution from vehicles will continue to decline.  EPA tightened automobile emission standards in 1994, 2001 and 2004.9  The 2004 standards require a reduction of at least 90 percent below the emissions of the average car currently on the road.  Most of the benefits of this standard will not be fully realized until more than a decade from now as older cars are progressively retired.  The 2004 regulations also require the same low emissions from SUVs and pickup trucks.  The average automobile on the road 20 years from now will therefore be about 90 percent cleaner than the average car in use today.10

Growth in driving will do little to offset these per-mile emissions improvements. For example, if total driving increases 3 percent per year over the next 20 years - say, in a rapidly growing region - total miles driven would increase about 80 percent.  But the net effect of an 80 percent increase in miles driven and a 90 percent decrease in per-mile emissions is an 82 percent reduction in total automobile emissions.

Emissions from on- and off-road heavy-duty diesel vehicles will also sharply decline.  EPA tightened standards for new diesels several times during the last 20 years.11  The benefits of these standards will continue to accrue as earlier models are retired.  Additional standards are coming down the pike.  Beginning in 2007, new diesel trucks will have to reduce NOx, soot and other emissions 90 percent below previous new-vehicle requirements.12  Similar requirements apply to new off-road diesel vehicles and equipment starting in 2010.13

Industrial Emissions.  Industrial emissions will also continue to decline.  EPA's Clean Air Interstate Rule (CAIR) will require power plants to meet summer "ozone-season" standards for NOx year-round in 2009.14  And compared with 2003 emissions, CAIR requires a 53 percent reduction in power plant SO2 by 2010, a 70 percent reduction by 2020 and ultimately a 77 percent reduction.15  Rules to reduce emissions of a variety of potentially hazardous pollutants from more than a dozen industries come into effect over the next few years.16

Compared with past decades, most air pollution has already been eliminated.  And already-adopted requirements will eliminate most of the remaining pollution emissions.

Behind the Myth: Widespread Misinformation

While air pollution levels have declined, polls show most Americans think air pollution has stayed the same or even increased and will continue to increase in the future.17  The reason:  Most information on air pollution from environmentalists, regulators and journalists - the public's main sources for information on the environment - is false.  Here are just a few examples:

  • In November 2001, the Sierra Club wrote that "smog is out of control in almost all of our major cities" - after two years of the lowest recorded levels of ozone and fine particulates (PM2.5) nationwide.18 
  • In 2002, the Public Interest Research Group published Darkening Skies, which claimed PM2.5 was increasing - near the end of a fourth consecutive record-low year for PM2.5.19
  • In April 2004, the Washington Post lamented, "Ozone pollution has declined slightly over the past 30 years" (emphasis added) - although, nationwide, the total number of times the 1-hour and 8-hour ozone standards were exceeded had declined 95 percent and 65 percent, respectively, since the mid-1970s.20
  • A recent USA Today article claimed Americans now drive "vehicles that give off more pollution than the cars they drove in the '80s" - despite spectacular improvements in automobile emissions performance during the last few decades.21

"Activists, regulators and journalists have falsely claimed air pollution is worse."

Similarly, in December 2005, EPA proposed a lower 24-hour standard for fine particulates (PM2.5) that would nearly double the number of areas violating the federal standard.22  Yet activists and journalists created the impression that the EPA had not tightened the standard at all.  "EPA proposes ‘Status Quo' revisions to PM NAAQS [particulate matter standard]," claimed an American Lung Association press release.23  According to Clean Air Watch, another environmental group, "President Bush gives early Christmas present to smokestack industries."24  The Atlanta Journal-Constitution headline read, "EPA Barely Budges on Soot; Health Advice Disregarded."25

Furthermore, 2003 through 2005 were the three lowest ozone years on record.   This should have been cause for celebration.  But just the opposite occurred:

  • Shortly after the 2005 ozone season ended, a press release from Clean Air Watch proclaimed, "Smog Problems Nearly Double in 2005."26
  • Pennsylvania's Department of Environmental Protection warned, "Number of Ozone Action Days Up from Last Year."27
  • EPA's New England regional office noted, "New England Experienced More Smog Days during Recent Summer."28
  • Referring to 2005 ozone levels in Connecticut, a New York Times headline lamented, "A Hot Summer Meant More Smog."29

Ozone levels were indeed higher in 2005 than in 2004 - because 2005 was only the second lowest ozone year since the 1970s, while 2004 was the lowest.  Ozone levels were so improbably low in 2004 that it would have been astounding if ozone wasn't higher in 2005.  Nevertheless, 2005 was one of the hottest years on record, but ozone levels remained at historic lows.  Opinion makers turned this success into an apparent failure.

Alarmists Coast to Coast.  Journalists and activists have also created the false impression that much of the country has high levels of air pollution.  During the last few years dozens of newspapers around the country have claimed their city or state has "some of the worst air pollution in the nation" or some variation of that phrase.30  In fact, only parts of the Los Angeles metropolitan area and the San Joaquin Valley have the worst ozone or soot in the country.31  No other area of the United States even comes close.

"The air is getting cleaner in the worst areas of the country."

In one particularly embarrassing example, on May 1, 2001, five separate Associated Press (AP) stories claimed that Maryland and Connecticut each have "some of the worst smog in the country," New Jersey has "some of the nation's dirtiest air," 11 Southern cities are "among [the] nation's most polluted," and "some of the country's worst air can be found in the San Joaquin Valley."32

Newspapers make these "some of the worst" claims even in many areas that comply with federal ozone and/or PM2.5 standards.  These exaggerations mislead tens of millions of Americans into believing their air is far more polluted and dangerous than it really is.  The lack of temporal context adds to the misperception.  Someplace in the United States has to be the worst at any given time.  But even in the "worst" areas of the country, air pollution is much lower now than it used to be.  For example, Riverside, Calif., has the highest PM2.5 levels in the country.  But PM2.5 in Riverside has dropped more than 50 percent since the early 1980s.33  Ignoring and obscuring these large improvements widens the gap between public perception and actual air quality.

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