This course covers chemicals in our environment and in our bodies and how they impact our health. It addresses policies and practices related to chemicals, particularly related to how they get into our bodies (exposures), what they do when they get there (toxicology), how we measure them (biomonitoring) and their impact on our health. Most examples are drawn from the US.
Lecture 9: Air Quality Regulation - Samet
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From the course by Johns Hopkins University
Chemicals and Health
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From the lesson
Week 5 - Chemicals Policy: What do we do about chemicals & health?
So far we’ve covered: how chemicals get into our bodies and how we measure them, what our bodies do with them and what they do to our bodies, and how that ultimately impacts our health. Now we turn to policy and how society addresses the impact of chemicals on health.
We will hear from a non-profit group that works to change policies such as laws & regulations related to this area. Then we’ll hear how such changes have impacted our health and environment historically, looking specifically at air quality regulation in the US.
After you view the lectures in Module 5, there is a second peer-reviewed writing assessment that aims to gauge your shift in understanding the complex relationship between chemicals and health (again grade each other generously).
Meet the Instructors
Dr. Megan Weil Latshaw, PhDCo-Director of the Masters Programs in Environmental Health
Bloomberg School of Public Health
Beth A. Resnick, MPHAssociate Scientist
Health Policy and Management
[MUSIC]
Hello.
I'm Jonathan Samet.
I'm at the University of Southern California Keck School of Medicine,
in the Department of Preventive Medicine.
My topic is going to be Air Quality Regulation.
What I'm going to tell you about is the general approach to using science to set
regulations, and the applications of those general principles to air quality control.
I'm going to focus in on the specific example of what we do
in the United States, and then at the end, just take a look at the global picture.
We've gotten very serious about air quality regulation after some
truly dramatic episodes of death caused by air pollution.
These took place across the last century, the Meuse Valley in 1930,
Donora Pennsylvania here in the United States in 1948,
most importantly the London fog of 1952.
The London fog of 1952 was actually not a fog but a deadly episode
of air pollution with air pollution reaching levels perhaps 100 times, or
more what they are today even in Los Angeles.
Over the week of the fog, and subsequently thousands of people,
10,000, 20,000 died prematurely, and
these episodes were a wake up call to the need for control of air pollution.
The colleague, a friend of Dr. David Bates, an important figure in respiratory
medicine and air-pollution research, was actually in the emergency department in,
in London during the fog of 52 and wrote about it.
He talked in a paper shown here about,
the efforts to limit air pollution that followed in the decades after the fog,
noted that these improvements were a proper memorial to those who gave their
lives, or who were killed, actually, during this episode.
Now we care about air pollution because it is an important cause of
premature death and disability.
Here are data taken from the global burden of disease 2010 study,
showing the disease burden associated with two types of air pollution.
Household air pollution from burning indoors, and, outdoor, or
ambient particulate matter pollution,
which you can see comes in quite high on the list of causes of disability.
So we have a strong rationale for doing something.
Air pollution can kill acutely, and it can cause disability chronically.
So, I'm going to turn now to translating evidence into policy.
Now, here's just a very general scheme about,
how we make such decisions and use the evidence around the environment.
The two streams of data generically shown is epidemiology.
Toxicology, with an assessment as to whether there's a hazard.
That is, does an environmental agent cause an adverse effect?
And then if so, how much is the risk?
And we quantify there using QRA, as I've shown the slide, or
Quantitative Risk Assessment.
And based on what the burden of disease, is how much risk there is.
Decisions are made about the need for regulation, and regulation follows.
And I'll just point to a few key reports here on risk assessment.
The red one is known as the red book, in fact, and
that's a report from 1983 from the U.S. National Academy of Sciences.
Then quite some years later, about 2009, the silver book, Science and
Decisions describing new approaches new concepts around risk assessments.
So an understanding of risk underlies a regulation, and
science figures in, of course.
The evidence is what is critical for, making decisions, and
of course uncertainty refers to what we don't know.
And as we think about the need to act and
what actions might be taken, we're constantly looking for the foundation in,
in the evidence we have, and trying to see where there are gaps.
And particularly if there are gaps that are critical that should be addressed by
research before action is taken.
So, perfect certainty may be hard to achieve, but
we may need some questions answered before we move
forward because answers will guide what regulatory path we might take.
So, in this schematic scale here,
we have evidence weighing down, and certainly pushing against it.
And then also many other forces, in the end
influence decision making around environments, so, clearly it would be
naive to say that political issues don't matter, their costs are not important.
The push from various advocates and activists is also important,
and again their might be push in one or another direction.
So, some general concepts about Science-based regulation.
So let's turn then to the example of air quality regulation in the United States,
and how we've used evidence to drive air quality.
Well, I've pointed to the London fog of 52 as a real turning point, but
there have been others, Los Angeles, 1943, the first major episode of smog, or ozone,
or photo chemical oxidant pollution, and here is a picture of LA at the time.
And again then we knew very little about this type of air pollution, in fact,
it was later that Hagensmith received the Nobel Prize, for describing
the phytochemistry that leads to the development of this type of pollution.
And then, of course, in the east coast,
there were very high levels of pollution from coal burning cars and industry.
And again, here's a picture from New York City, of one of the so-called brown outs,
very high levels of air pollution occurring there.
So, again in the United States,
we began to think about air quality regulation as well.
There are decades of Science, following the London fog of 52,
really sort of contemporary air pollution epidemiology began in that decade and
continues, and here I've schematically shown, what the questions were
over the last 60 years now, and what some of the key study types and methods were.
At the outset there was an interest in what are the adverse effects of
air pollution, and many studies were done.
Some are descriptive, health and quote clean communities compared with health,
and quote, dirty communities with regard to air, times-series studies.
But then, in the 70s, the Harvard six city study was initiated, a very large
covert study directed at air pollution in both children and adults.
And, of course, one of the findings of this,
study about 20 years after it began was that,
higher levels of air pollution were associated with increase risk of death.
The ACS American Cancer Society's study has also been used for
that purpose, and I'll note at USC we have the Children's Health Study, or CHS.
An important multi community study of children, and air pollution.
So we generated a lot of data,
much of it coming recently from time series studies and other kinds of studies.
So these studies have shown risks, described here for
a variety of effects including, short-term increases, and
risk of dying, longer-term increases, and risk, and dying, and then various effects.
Effects on the lung, of course, many on the cardiovascular system,
and reproductive effects, and we know that some people are more
susceptible than others, people with heart disease, people who are older,
people with underlying lung disease.
So in the United States we regulate air pollution through the Clean Air Act
which was first pass in 1970, year in terms of environmental
regulations, so the important things about the act is that it's comprehensive.
It addresses outdoor air quality standards, so called
National Ambient Air Quality Standards, or NAAQS, covers all sources as well, and
it puts a burden on the state, and the EPA to address air pollution problems.
Now from the point of view of the major air quality standards for
concentration they come under section 109 of the act, and
the primary standards which are based in evidence.
Call on the administrator, to set standards which are protective of
your public health with an adequate margin of safety.
So, there's a heavy burden for
public health protection that is placed on the EPA administrator, for
these pollutants which include things like ozone, airborne particles, and others.
In fact, I'm going to show you the list in the la,
next slide after this with the various criteria pollutants.
Well, here's the process now by which EPA sets these standards,
it's a complicated flow diagram.
But you might notice sort of the entry point up at the top, is Peer-reviewed
scientific studies, and that is really the foundation for the air quality standards.
The agency first puts together something called,
the Integrative Science Assessment, or
ISA, that is a review of all the relevant evidence,
particularly that over the five years since the last assessment.
That is reviewed by the public and by something called CASAC, or
the Clean Air Scientific Advisory Committee.
And based on findings in the ISA, a risk and exposure assessment is carried out.
This documented analysis looks at, who is exposed?
And what are the risks?
And it compares alternative control scenarios as well.
The policy assessment, gets at what should be done,
what will be the benefits of changing concentrations to particular levels?
It gives options to the EPA administrator as he or
she, sets the standard to address the mandate of section 109 to
protect the public health, with an adequate margin of safety.
You might notice throughout this diagram there's, review by CASAC, and
public comment.
When the agency has, developed a policy assessment, and
options on the standard, it goes off to be reviewed by other agencies.
It will end up with the office of management and budget, and
eventually, a decision is made.
Now, here are the standards, and
you'll notice that there are six criteria pollutants at the moment.
They have changed over time, we keep a Lead standard because there are still some
point sources that are important.
Particulate matter pollutions particularly are important as both a primary, and
a secondary pollutant in fact nitrogen dioxide and
sulfur dioxide contribute to the formation of air borne particles.
These levels have come down, progressively over time.
So the states are required to meet these standards and
develop implementation plans to do so.
But the clean air act, has been a success and
this is a graph taken from the Environmental.
Protection Agency and you can see that at an era of economic growth and
increasing energy consumption, more vehicle miles traveled,
pollution emissions have gone down, for the major pollutants.
And in fact, if you were to look at,pollution levels,
you would see that they have gone down as well.
So here in Los Angeles, 30 40 years ago, very high levels of ozone were a problem,
visibility was limited, people's eyes burned, and there's been a great deal of
improvement since then, such that, it is very rare, that I'm actually bothered,
let's say by burning eyes, or scratchy throat because of air pollution.
The Clean Air Act has been in place since 1970, it was last revised in 1990.
This is an editorial with reference for you from a paper I wrote a few years ago,
that provides my perspective on where the Clean Air Act sits, and
where we might take it when the time comes for it's revision.
So there are some challenges to continuing this evidence based approach and
I'm just going to spend a moment talking with you about them.
One is that of course, the levels have come down, and here's a hypothetical graph
of particulate matter level risk, what I've called policy-related background.
That's essentially the unavoidable level of pollution in the air from nature and
from some cross-boundary transportation.
The improvement is great, but the range over which we're
now studying exposures is, is narrower, and we're trying to
answer some tough questions about what are the risks within these exposure levels?
And could there be thresholds below which there is no risk?
So an important question is,
how does risk relate in a quantitative way to the concentration of the pollutant?
And use just some hypothetical graphs of risk and different concentrations.
And the point is, depending on what the shape of the curve,
there could be very different levels of risk at different concentrations,
again depending on which is right.
So, you can see that a linear threshold model might be showing no risk,
while I supra-linear model might be showing a great deal of risk.
So this is the kind of question that we need to answer now to guide regulators.
People have been pooling data and analyzing it for this purpose.
There's a recent paper from colleagues that look at what they call an integrated
risk function, coming up with curves that look like this for
different outcomes, IHD, schema car disease, LC, lung cancer.
And, you know, importantly, in these plots,
you can see a few things that the shapes are, are a little bit different,
they generally tend to flatten out at higher concentrations.
So, again, what is indicated here is that
there is substantial uncertainty remaining to be addressed.
And this becomes important as we think about, achieving the lowest risk
possible which is going down to, as close to the background risk.
That risk from the national occurring of the pollutant as possible.
There are clearly places that have unacceptable risks.
I am going to talk about that.
There are maybe places where we can get to what I have called the achievable risk,
but not what is the optimum risk, so,
these relationships are important in the practice.
So, just finishing up, let's look worldwide, let's go global.
First off,
here is a map of estimated particle levels in the air based on satellite data.
On this plot, blue is good and the deeper towards red, bad.
And, you can see that the pollution is not coming from North and South America at
present, but it is largely in Africa, Asia, and a little bit towards Europe.
The problems of particles and high levels of air pollution,
have shifted away from countries like the UK, the United States, where they have
been decades of air quality control to India, China and cities of Africa.
And in those countries, again back to the global burden,
there's a substantial burden of air pollution attributable morbidity and
deaths, shown here the estimated numbers in the US, India, and China.
The World Health Organization has guidelines, and
these are being updated now.
These are evidence based, but
clearly there is more evidence now than in 2005 when this volume was produced.
Here are the WHO Air Quality guidelines.
They are a little bit more relaxed, generally, than the US EPA guidelines.
There's that recognition, that the problem shown here,
for example, are very high levels of, of pollution in India,
might not be well addressed by, the kinds of standards that are, strict,
and are in the WHO guidelines table I just showed you.
So acknowledging that providing unrealistic standards would not
help low and middle income countries.
The WHO volume also proposed that tier targets.
So that for China, or India, or
East Africa, there would be WHO guidelines, and they're there for
everybody but there would also be targets that should be achieved.
Right now, if we look, 150 micrograms per cubic meter, PM10, there are many cities
that would be achieving levels ten times that on a fairly routine basis.
So, just closing, of course, these guidelines, all this control is important,
because essentially, we just don't want the London Fog of 52 to happen again.
And without ongoing, persistent, and perhaps, tougher air quality regulation,
I'm concerned there is the potential for there to be another London Fog
of 52 like episode whether it's in the city of China, India, or
Africa, but it's clear we are pushing it to the limit in some of these cities.
So to summarize, I've talked about how we approach air quality regulation,
how we use Science, how non-Scientific factors are also important.
And I showed you in the example of the United States, air quality regulation has.
Worked, and now, let's make sure it works everywhere.
Thank you.
[MUSIC]
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