Introduction
For over 41 years,
members of our staff have performed scientific research on the
effects of air pollutants on the environment. There are hundreds
of pages on this web site that focus on the various aspects associated
with air pollution research. In order to assist you in identifying
which pages might be of interest to you, this introduction provides
insight into some of the more important scientific issues. At
anytime, please feel free to visit our Table
of Contents.
From our years of experience, we have learned
that it is what we know about pollutant exposure and its effects
on humans and the ecosystem that are the most important aspects
of selecting appropriate standards to protect the public. Using
the most current research information, we continuously assess
the scientific rationale for air pollution standards promulgated
nationally and internationally. Our research sponsors are government,
industry, and environmental groups. Both national and international
institutions support our research efforts. Thousands of individuals
from around the world visit our web pages weekly. Some of the
most popular web pages visited are those associated with (1) maps summarizing violation areas
for criteria air pollutants, (2) natural background of surface
ozone, (3) the biological importance of the higher hourly average
air pollution concentrations more than the mid- and lower-level
values, (4) our exposure- and dose-response research on vegetation
and human health, (5) the "piston effect" and how it
affects the reduction of hourly average surface ozone concentrations
as air pollutant emissions are reduced, (6) our global sulfur
emissions database from 1850-1990, (7) spatial interpolation
of surface ozone (i.e., kriging), (8) concerns about assumptions
associated with epidemiological modeling, (9) our peer-review
publications list, and (10) our Albert Einstein quotations with
references. The monthly summary figure
below shows some of the locations from where some of our web
site visitors originate. There is a large percentage of return
visitors (i.e., 35%) who routinely access the A.S.L. & Associates
web site.
In April 2004, EPA
designated 474 counties as nonattainment for the 8-hour 1997
ozone standard. As of June 7, 2010, there are 264 counties in
nonattainment. Our research results are showing that evidence
indicates that the 8-hour ozone standard may be more difficult
to achieve and remain in attainment in many locations in the
United States than believed by the Agency. Several of the areas
that were changed from nonattainment to attainment status by
the EPA violated the standard during the 2005-2007 period. For
more information about the Agency's implementation of the 8-hour
ozone standard, please click here.
It is important
to look closely at the scientific data. For ozone, an important
phenomenon is the "piston"  effect. The EPA has confirmed the existence of the
effect that was first described by A.S.L. & Associates
in November 1996 and published in the peer-review literature
in 1997 and 1998. The Agency, after reviewing 25 years of air
quality data, reported that there were larger reductions in the
higher ozone concentrations than the middle values. To attain
the 8-hour ozone standard of 0.075 ppm, the middle values must
be reduced. The "piston" effect defines whether the
8-hour ozone standard is achievable or just a bureaucratic goal.
Most recent emission reduction modeling by the EPA and research
groups is illustrating the importance of the "piston"
effect in attaining the 8-hour standard. Based on scientific
evidence that has been published in the peer-review literature,
there is concern among some scientists and engineers that the
8-hour ozone standard may become an elusive goal that will continue
to be violated in many locations in the United States long after
control strategies are implemented. In the EPA's most recently
published trends report for ozone (http://www.epa.gov/airtrends/ozone.html),
the Agency indicated that
O3 levels are still decreasing nationwide, but the rate of decrease
for both the 1-hour and 8-hour levels slowed during the 1990s.
For large declines in ozone levels in 2003 and 2004, the Agency
notes that the summer of 2003 was slightly cooler than normal
in the East and the summer of 2004 was much cooler than normal.
The cooler weather is more than likely the reason that improvements
were noted for 2003 and 2004. The findings
show that the "piston" effect may be affecting the
ability of the Nation to attain the 8-hour ozone standard. If
the limitations associated with the"piston" effect
are ignored, the EPA and others will continue to push for greater
emission reductions that will not result in improvement to surface
ozone levels. For more information on this important subject,
please click here.
At a meeting that took place on August
24-25, 2006 in Durham,
NC, the EPA's Clean Air Scientific Advisory Committee (CASAC)
recommended a more stringent standard than the 8-hour 0.08 ppm
ozone standard. The majority of CASAC's members recommended an
8-hour ozone standard of 0.070 ppm. The selection of 0.070 ppm
implies that a design value of 0.071 ppm would violate a 0.070
ppm standard. There is considerable uncertainty associated with
the (1) epidemiological evidence and (2) data points at the 0.04
and 0.06 ppm levels in the EPA's dose-response function derived
from the controlled human exposure experiments. For the secondary
ozone standard, CASAC recommended the W126 cumulative exposure index integrated over a 3-month growing
season period measured daily from 0800 to 1959 hr. In June 2007,
the EPA Administrator proposed the W126 index as the secondary
ozone standard. Such a secondary ozone standard, in its current
form, would overestimate vegetation effects. Both the primary
and secondary standard recommendations by CASAC were reflected
in the final version of the EPA Ozone Staff Paper. On March 12,
2008, the EPA Administrator made the final decision on the human
health and vegetation ozone standards. EPA revised the 8-hour
"primary" ozone standard, designed to protect public
health, to a level of 0.075 parts per million (ppm). EPA decided
not to adopt the W126 exposure index. Although the EPA
Administrator recommended the W126 as the secondary ozone standard,
based on advice from the White
House (Washington
Post, April 8, 2008; Page D02), the EPA Administrator made the
secondary ozone standard the same as the primary 8-hour average
standard (0.075 ppm). In May 27, 2008, health and environmental
organizations filed a lawsuit arguing that the EPA failed to
protect public health and the environment when it issued in March
2008 new ozone standards. On March 10, 2009, the US EPA requested
that the Court vacate the existing briefing schedule and hold
the consolidated cases in abeyance. EPA requested the extension
to allow time for appropriate EPA officials that are appointed
by the new Administration to review the Ozone NAAQS Rule to determine
whether the standards established in the Ozone NAAQS Rule should
be maintained, modified, or otherwise reconsidered. EPA further
requested that it be directed to notify the Court and the Parties
within 180 days of the Court's order vacating the briefing schedule
of the actions the Agency has taken or intends to take, if any,
with regard to the Ozone NAAQS Rule, and the anticipated time
frame for any such actions.
On September 16, 2009,
the EPA announced it would reconsider the 2008 national ambient
air quality standards (NAAQS) for ground-level ozone for both
human health and environmental effects. The Agency planned to
propose any needed revisions to the ozone standards by December
2009 and issue a final decision by August 2010. On January 7,
2010, the EPA announced on its web site its proposal to strengthen
the national ambient air quality standards for ground-level ozone.
The EPA's proposal decreases the 8-hour “primary” ozone
standard level, designed to protect public health, to a level
within the range of 0.060-0.070 parts per million (ppm). EPA
is also proposing to establish a distinct cumulative, seasonal
“secondary” standard, referred to as the W126 index, which is designed to protect sensitive vegetation
and ecosystems, including forests, parks, wildlife refuges, and
wilderness areas. EPA is proposing to set the level of the W126 secondary standard within the range of 7-15 ppm-hours.
The proposed revisions result from a reconsideration of the identical
primary and secondary ozone standards set at 0.075 ppm in March
2008. On August 20, the Agency announced that it will delay its
final announcement to on or around the end of October.
There are still
many uncertainties associated with the science that was used
to support the development of the 8-hour ozone standard. For
over 29 years, environmental groups, industry, and government
officials have worked with A.S.L. & Associates to provide
them with the latest scientific information on ozone and particulate
matter. We have carefully noted the limitations of the science
involved in the decision-making process. The June 1997 Feature
Article in Environmental Science & Technology, the
September 1997 New Directions Column in Atmospheric Environment,
the June 1998 Policy Analysis article in Environmental
Science & Technology, the May 2001 peer-reviewed paper
in the Journal of Geophysical Research discusses several
of the important issues described on the various web pages associated
with this site and the uncertainties associated with the underlying
science. Four important issues that we address in these web pages
are
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The EPA assumes that the range of policy-relevant
background ozone levels is 0.015 ppm to 0.035 ppm. Is this assumption
correct? Based on a review of actual ozone concentration information
and our own research results, actual policy-relevant background
ozone levels are higher than the theoretical levels proposed
by the Agency or theoretical modeling efforts, which are subject
to great uncertainty. The unanticipated higher ozone policy-relevant background levels we believe play a major
role in the efficacy of reducing the mid-level hourly average
concentrations, especially in the springtime. |
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Is there a way to get around the "piston"
effect? Probably not. The "piston"
effect apparently controls the ability of a specific violating
area reaching attainment in a reasonable time frame. The result
of this effect is that the 8-hour ozone standard of 0.075 ppm
may actually be a "target" that may never be achieved
at many locations in the United States. The June 1998 policy
analysis article in the peer-reviewed journal, Environmental
Science & Technology, discusses this effect in detail.
Additional articles dealing with the difficulty in achieving
the new standard have been published in peer-reviewed journals.
For a review of some of these articles, please visit our publications page. The "piston"
effect will limit our ability to consistently attain the 8-hour
ozone standard of 0.075 ppm. What causes the "piston"
effect? Our current research is getting closer to the answer. |
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What is the result of EPA using a chemistry
transport model to generate highly uncertain estimates for background?
Actual levels of policy-relevant background are higher than the
models suggest and therefore, inadequate estimates of policy-relevant
background ozone concentrations will result in an overestimate
by the EPA of the human health risks associated with 8-hour ozone
levels. |
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The EPA has indicated a pattern
of inconsistent results in epidemiological time-series studies
that is troubling. The epidemiological evidence has played a
disproportionately large role in the policy making process. Time-series
findings indicate associations of mortality with not only PM
and ozone, but with all of the criteria pollutants. Because results
of time-series studies implicate all of the criteria pollutants,
findings of mortality time-series studies do not seem to allow
us to confidently attribute observed effects specifically to
individual pollutants. This raises concern about the utility
of these types of studies in the current NAAQS-setting process.
We have commented on the limitations associated with the use
of epidemiological
results in the current
NAAQS-setting process. |
Scientists, engineers, and policy makers
are focusing their attention on assessing how attainable a 0.075
ppm 8-hour ozone standard is. A.S.L. & Associates hopes you will take the time
to carefully read the scientific material provided here and learn
more about the science that will affect our ability to meet the
0.075 ppm 8-hour ozone standard. Much of our attention in the
last few years has been focused on policy-relevant background,
the frequency distribution (i.e., rollback) scenarios that result
from emission reductions in NOx and VOCs, human health and vegetation
dose-response modeling, and the shortcomings associated with
epidemiological modeling. We appreciate having the opportunity
to provide you with our research information. Maps
have been prepared that identify criteria pollutant violation
areas. If you desire further information, please contact A.S.L.
& Associates.
By introducing the 8-hour ozone standard
in 1997, the U.S. EPA began an unintentional experiment to quantify
how important anthropogenic emissions are in comparison with
natural emissions and processes. In June 2000, Canada joined
the experiment by passing an 8-hour ozone standard of 0.065 ppm.
California has passed an 8-hour, 0.070 ppm ozone standard. The
"piston" effect, a natural controller of ozone concentrations,
will probably dominate the ability of states and provinces to
attain the 8-hour ozone standard. We continue to perform our
research and report, both in the peer-review literature and on
this web page, our results. If you are interested in becoming
a sponsor of our on-going research, we welcome the opportunity
to work with you. We hope you will return to our web page
again and again to continue to learn more about this most fascinating
topic.
Besides our focus on surface ozone on our
web page, we also perform research on particulate matter, epidemiological
methodologies, risk assessment, and other important scientific
topics. Our most current research on the epidemiological methodologies
is showing serious concerns
about the statistical approaches used in assessing the effects
of both particulate matter and ozone on human health. We have
provided a Multimedia Center web
page that provides streaming audio and video material that will
help you understand the important scientific issues that we have
been addressing over the past several years. Thank you for taking
the time to visit our web page and we hope that the material
provided on these pages is helpful to you.
Science is both interesting and fun. It
is when policy makers attempt to work with the current state
of science that things really get exciting. Science is the search
for truth. Scientists have an obligation to provide guidance
to policy makers to assure that scientific facts are presented
in such a manner that they are accurate and not obfuscated for
political purposes. The purpose of this web page is provide the
general public, scientists, policy makers, and decision makers
the opportunity to review the science that helps make the decisions
that influence the direction in which our environmental policies
are directed. As indicated above, every week thousands of visitors
from around the world read the materials contained within our
web pages. To start your visit on our web pages, please visit
our Table of Contents or News
sections. Welcome aboard!
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