Dirty air: Mission Accomplished

The Bush US Environmental Protection Agency (EPA) has done just what we have come to expect them to do: wimped out on keeping Americans truly safe. Oh, you expected them to protect your health? Yes, they will. In partnership with the Easter Bunny. The Tooth Fairy had enough and decamped to the Democrats.

What's this about?

When I first looked at air pollution epidemiology, the measurements of particulate matter in the air was in pretty crude terms, Total Suspended Particulates. You measured TSPs by sucking a measured volume of air through a filter, weighing the filter and then expressing it in terms of the mass of particles (of all kinds) trapped by the filter per unit volume of air (usually a cubic meter, the volume of a cube one meter on a side). A lot of the data on health effects on particulate matter in the air, then, also used even older measures, such as "smoke" measures. "Then" was a long time ago. So long ago that the Democratically controlled Congress could even be called "liberal" without anyone fainting.

Now big heavy particles in the air settle out rapidly, coating your car and window sills with a gritty layer. Better on your window sill then in your lungs, though. Particle size is measure in microns, a millionth of a meter. Too small too see anything the size of a micron. Your red blood cells are 8 microns in diamter. Particles under 5000 microns (µ) fall slowly, roughly at a rate proportional to their "size." I put size in quotation marks because it isn't physical size that's measured, since the particles might be very irregular in shape, but the size of a standard spherical particle that behaves aerodynamically like the particle being measured. Under 10 µ the particles settle so slowly they remain suspended for long periods and are part of the Total Suspended Particulates.

Even most of these are also too big to get down very far into your lungs, however. The reason is that your upper respiratory tract makes a lot of bends and sharp turns and the larger particles can't make the turns fast enough at the speed of inhaled air to avoid careening off course and smashing into the side walls of the conducting tubes that carry air into the lower reaches of your system. It's like the difference between a huge semi-trailer trying to make sharp turns at high speeds. To do that you need a sports car. That's the smaller particles, those under 5 µ. They can make it down into the lower reaches of the lung. And the ones under 2.5 µ get right down into the business part of the lung, the very delicate tissues that separate the inhaled air from your circulating blood. This part of the lung has to be super thin to allow oxygen molecules to diffuse into the blood and carbon dioxide molecules to diffuse out to be exhaled. It also has to be kept clean. It is the fine particulates that get in there.

The older TSP measurements upon which much of the epidemiology was based used PM10 as a measure, the particulate matter less than 10 µ in size. Then in the 1990s a landmark series of studies came out of the Harvard School of Public Health, showing variations in daily sickness and daily mortality in relation to the finer particulates, the PM2.5 fraction. That led to the current fine particulate standard of 65 micrograms per cubic meter over a 24 hour period. But the health data clearly showed that wasn't adequate either. There was overwhelming scientific evidence of increased morbidity and mortality at those levels, too. So EPA embarked on a new rule making.

This week we got the results. From the Environmental Defense Fund (whose scientists are quite expert in this area):

EPA finalized its proposal to lower the 24-hour fine particle standard (from the current 65 micrograms per cubic meter to 35 micrograms per cubic meter) and claims that is sufficient. It is not. EPA's risk assessment data and modeling analyses show that the annual fine particulate pollution standard must be lowered to prevent the preponderance of premature deaths from particulate pollution and to spur meaningful pollution cuts, including further region wide reductions from coal-fired power plants across the eastern United States.


EPA's action ignores: the recommendations of EPA's own Clean Air Scientific Advisory Committee, the advice of EPA's own Children's Health Protection Advisory Committee, the recommendations of 100 leading research scientists and physicians, and the unprecedented comments of some two dozen national and local health organizations. The EPA Office of Research and Development concluded in a July 2006 report that the most recent scientific studies continue to underscore and strengthen evidence for the serious adverse health effects of particulate pollution.

More than 2000 peer-reviewed scientific studies examining the health effects of particulate pollution have been published since the EPA last updated the nation's health standards in 1997. These studies clearly show that particulate pollution imposes a heavy burden on human health at levels well below the current standards. (EDF Press Release)

EDF is an environmental advocacy group. But I know their scientists and I know the scientists who have been doing the fine particulate epidemiology for the last several decades.

EDF is right about this. And EPA is, well, EPA under the Bush administration. Their Mission Accomplished.

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I have always been in favor of reducing not only greenhouse gasses but also particulate pollution in the air. BUT seems like we have put ourselves into a deep bind. Turns out that the particulates pick up water and form a reflective shield that causes global dimming. This offsets some of the global warming. Fear is that if the pollution is diminished the warming will accelerate. What a species we are eh? We keep fixing things and then find new problems to fix. My axiom is "Every Solution has a Problem".. Looks like we might solve ourselves into extinction. We solve disease and get overpopulation and hunger, we solve hunger and get more overpoplution and land degredation. I could go on..and on..and on.


Why the Sun seems to be 'dimming'
By David Sington

We are all seeing rather less of the Sun, according to scientists who have been looking at five decades of sunlight measurements.

They have reached the disturbing conclusion that the amount of solar energy reaching the Earth's surface has been gradually falling.

Paradoxically, the decline in sunlight may mean that global warming is a far greater threat to society than previously thought.

The effect was first spotted by Gerry Stanhill, an English scientist working in Israel.

Cloud changes

Comparing Israeli sunlight records from the 1950s with current ones, Dr Stanhill was astonished to find a large fall in solar radiation.

"There was a staggering 22% drop in the sunlight, and that really amazed me." Intrigued, he searched records from all around the world, and found the same story almost everywhere he looked.

Sunlight was falling by 10% over the USA, nearly 30% in parts of the former Soviet Union, and even by 16% in parts of the British Isles.

Although the effect varied greatly from place to place, overall the decline amounted to one to two per cent globally every decade between the 1950s and the 1990s.

Dr Stanhill called it "global dimming", but his research, published in 2001, met a sceptical response from other scientists.

It was only recently, when his conclusions were confirmed by Australian scientists using a completely different method to estimate solar radiation, that climate scientists at last woke up to the reality of global dimming.

My main concern is global dimming is also having a detrimental impact on the Asian monsoon ... We are talking about billions of people
Professor Veerhabhadran Ramanathan
Dimming appears to be caused by air pollution.

Burning coal, oil and wood, whether in cars, power stations or cooking fires, produces not only invisible carbon dioxide - the principal greenhouse gas responsible for global warming - but also tiny airborne particles of soot, ash, sulphur compounds and other pollutants.

This visible air pollution reflects sunlight back into space, preventing it reaching the surface. But the pollution also changes the optical properties of clouds.

Because the particles seed the formation of water droplets, polluted clouds contain a larger number of droplets than unpolluted clouds.

Recent research shows that this makes them more reflective than they would otherwise be, again reflecting the Sun's rays back into space.

Scientists are now worried that dimming, by shielding the oceans from the full power of the Sun, may be disrupting the pattern of the world's rainfall.

There are suggestions that dimming was behind the droughts in sub-Saharan Africa which claimed hundreds of thousands of lives in the 1970s and 80s.

There are disturbing hints the same thing may be happening today in Asia, home to half the world's population.

"My main concern is global dimming is also having a detrimental impact on the Asian monsoon," says Professor Veerhabhadran Ramanathan, professor of climate and atmospheric sciences at the University of California, San Diego. "We are talking about billions of people."

Alarming energy

But perhaps the most alarming aspect of global dimming is that it may have led scientists to underestimate the true power of the greenhouse effect.

They know how much extra energy is being trapped in the Earth's atmosphere by the extra carbon dioxide we have placed there.

What has been surprising is that this extra energy has so far resulted in a temperature rise of just 0.6 degree Celsius.

This has led many scientists to conclude that the present-day climate is less sensitive to the effects of carbon dioxide than it was, say, during the ice age, when a similar rise in CO2 led to a temperature rise of six degrees Celsius.

But it now appears the warming from greenhouse gases has been offset by a strong cooling effect from dimming - in effect two of our pollutants have been cancelling each other out.

This means that the climate may in fact be more sensitive to the greenhouse effect than previously thought.

If so, then this is bad news, according to Dr Peter Cox, one of the world's leading climate modellers.

As things stand, CO2 levels are projected to rise strongly over coming decades, whereas there are encouraging signs that particle pollution is at last being brought under control.

"We're going to be in a situation unless we act where the cooling pollutant is dropping off while the warming pollutant is going up.

"That means we'll get reducing cooling and increased heating at the same time and that's a problem for us," says Dr Cox.

Even the most pessimistic forecasts of global warming may now have to be drastically revised upwards.

That means a temperature rise of 10 degrees Celsius by 2100 could be on the cards, giving the UK a climate like that of North Africa, and rendering many parts of the world uninhabitable.

That is unless we act urgently to curb our emissions of greenhouse gases.

K: Yes, particulates reduce warming by increasing albedo. That seems to be the Bush administration solution to global warming: reduce warming by choking us to death.

Revere and K: thanks for a great article and response, written in language easy to understand. I have copied and pasted them into a doc to use with my eighth grade environmental studies class.

By mary in hawaii (not verified) on 23 Sep 2006 #permalink

Mary, so glad to hear you will use both sets of info with your class. Revere, you are right - Bush and boys are heading us into a great abyss one way or another. Is that the plan? Or do they not realize that on this ball we call Earth we used to have space but now it looks like we sink or swim together. I debate that with myself constantly.

yes, post was very lucid and informative. good stuff.

Dimming. I read that when it appeared, and probably I live in a dim place, as I and many others have noticed the dimming. For ever so long I attributed it to memory - that bright sunlight of childhood that lasts and lasts and is somehow never the same.

Later, I ascribed it to the propensity of the people in this culvert (Ge. Switz, between two mountains) to being perpetually sensitive to the amount of sun and over the decades complaining more vociferously, as they do increasingly about anything, as many people are in shadow when the sun is still in the sky, and in winter, the lake of fog, as it is called -clouds trapped between the mountains at about 800 / 1000 meters- may block sunlight for weeks on end. .... Creating traffic jams that head straight up, everybody revving with handbrake on!

There are some valley-in-the mountains communities contemplating huge projects.

Giant Mirrors!

(serious stuff, will affect real estate values..)

But perhaps the most alarming aspect of global dimming is that it may have led scientists to underestimate the true power of the greenhouse effect.

Yup. Huh - huh.

Don't have time to find the link, but someone on Flu Wiki mentioned China does not even do as much regulation as we currently do, and their pollution, and birth defects and other problems are increasing, and, not staying within their borders - we all share the same air.

By crfullmoon (not verified) on 23 Sep 2006 #permalink

crfullmoon: China's air is unbelievably dirty. We have a lot of work to do in the US, but if you want to see what environmental regulation means (and not having it means) go to China, Russia, eastern Europe, and big cities like Cairo. We live in an environmental paradise -- in comparison. But of course we also have big problems we need to keep working on, because dirty air, water and unsafe food is still killing tens of thousands of our neighbors, friends, families and fellow citizens.

But think of this - if H5N1 becomes pandemic, possibly factories will shut down in China - particulate falls out of the air quickly - in days in fact. If the dimming is in fact holding down global warming it could accelerate. Once it reaches a certain threshold it becomes a positive feedback cycle - melting the permafrost and releasing more greenhouse gasses, and perhaps then melting the frozen methane in the oceans in which it goes into overdrive. Speculative for sure, but things have become fragile and very entangled and interconnected. What is the temperature at which uncontrolled positive feedback in global warming begins? How many factories have to shut down for how long before dimming ceases to moderate warming? What else happens if dimming ceases suddenly? Our drive to lessen pollution needs to be connected to reducing greenhouse gases or we may create worse problems than lung disease. Or our 8 gene friend H5N1 may cause effects that are unanticipated by slowing manufacturing due to employees too ill to work and thus precipate uncontrollable warming.

What to do? Does anyone really know anymore? I fear we are in very dangerous times, but it is not God that is bringing doomsday but us. BUT since God is in fact invented in our image its about the same thing eh?