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July 6th, 2011:

The Clean Air Act and Health — A Clearer View from 2011

NEJM | July 6, 2011 | Topics: Public Health

From my office, I have views of downtown Los Angeles and the San Gabriel Mountains. Air pollution infrequently obscures these views, and only rarely are my eyes and throat irritated by smog when I’m outdoors. The Los Angeles air of today is far better than that of the mid-20th century, when severe oxidant pollution, initially of unknown origins, threatened the health and welfare of the city’s residents. Severe smog was a common occurrence. Today, throughout the United States, air quality has improved greatly, and the last century’s severe, life-threatening episodes of air pollution, such as one that caused about 20 deaths in Donora, Pennsylvania, over a 3-day period in 1948, have largely been forgotten. The Clean Air Act of 1970 (CAA) has driven this progress, but we now face new challenges in air-quality management.

The 20th-century pollution episodes and the pervasive smoke problem in cities motivated increasingly stringent and sweeping laws and programs to address air pollution. For more than 40 years, the CAA, aided by amendments passed in 1977 and 1990, has been the foundation for U.S. air-quality management. It provides a broad regulatory framework, covering air-pollution standards, various stationary and mobile sources, acid deposition, and stratospheric ozone protection. Two sections of the law address the major pollutants in ambient air, including particulate matter, ozone, carbon monoxide, nitrogen dioxide, and sulfur dioxide, as well as lead, which ceased to be a widespread problem when it was removed from gasoline. These pollutants are referred to as “criteria pollutants,” thanks to a passage in the law that requires the administrator of the Environmental Protection Agency (EPA) to issue “air-quality criteria,” accurately reflecting the scientific evidence related to identifiable public health and environmental effects, for any substance designated as an air pollutant.

The CAA also requires the EPA administrator to set National Ambient Air Quality Standards (NAAQS) for pollutants for which air-quality criteria are listed. The language of the law on this point provides a strong public health mandate that has evolved through application and litigation. By intent, the NAAQS must protect susceptible groups within the U.S. population, although protection for the most susceptible may be unattainable. The achievement of what the CAA calls an “adequate margin of safety” does not imply that risk-free levels have been set, but that an acceptable level of risk has been reached, given uncertainties in the evidence. The costs of implementation and compliance are not to be considered in setting the NAAQS, although the law does call for costs to be considered in the setting of individual emission standards (e.g., for vehicles and electric utilities) that are intended to help meet the NAAQS. Under the CAA, the Clean Air Scientific Advisory Committee (CASAC, which I currently chair) provides peer review for the EPA’s reports and analyses that support NAAQS revisions.

Over the 40 years since NAAQS were first promulgated, they have led to progressive reductions in levels of criteria pollutants (see graph). Economic analyses indicate that these reductions have been highly cost-effective.1 However, as the EPA administrator now considers revisions to the NAAQS for particulate matter and ozone, the CAA’s tenets are being questioned. The questions are motivated by the possibility that even lower concentrations for the NAAQS will be proposed, leading to the designation of large regions of the country as out of compliance with the law; such a result would carry implications for many municipalities and states and multiple U.S. industries. The evidence supporting lowering of maximum levels comes largely from epidemiologic studies showing that current levels of particulate matter and ozone are adversely affecting public health. Discussion of the NAAQS and the CAA has been further complicated by a U.S. Supreme Court finding that the EPA has authority to regulate greenhouse gas emissions.

Over the remainder of 2011, the EPA’s administrator, Lisa Jackson, will make key decisions with regard to lowering the NAAQS for particulate matter and ozone. For ozone, she has reopened the 2007 decision of then-administrator Stephen Johnson to set the standard at 0.075 ppm as the 8-hour average, which was made on the basis of the scientific evidence available at the time and the CASAC’s recommendation that the limit be in the range of 0.060 to 0.070 ppm. Subsequently, the CASAC has reaffirmed that recommendation and answered additional questions about the scientific foundation for the ozone NAAQS. There is great interest in the administrator’s final decision; in its teleconferences discussing the EPA’s questions on ozone, the CASAC received input from 57 public commenters. Some raised concern that the evidence was still too uncertain to warrant lowering the NAAQS and that any mandated reduction would be costly and lead to the elimination of jobs, whereas others claimed that such a reduction was needed to meet the CAA’s requirement for protecting public health. For particulate matter, a decision will be forthcoming by year’s end with regard to recommended reductions in the 24-hour and annual NAAQS. If the administrator follows the CASAC’s recommendations, the NAAQS will be set at lower levels for both particulate matter and ozone.

As the NAAQS have been reset at lower and lower concentrations, the gaps between acceptable concentrations and irreducible background levels have narrowed, raising the question of how much lower the limits can be pushed. For ozone and particulate-matter pollution, because no thresholds have been identified below which there is no risk at all, the EPA is using scenarios of risk and exposure to gauge the effects of setting the standards at various concentrations and giving consideration to the burden of avoidable disease. In promulgating the NAAQS for these pollutants, the administrator must weigh the public health burden against the uncertainty of the scientific evidence related to lower concentrations, keeping in mind the CAA’s requirement for an adequate margin of safety. It is challenging for researchers to reduce this uncertainty, given the narrowing and low range of concentrations at issue and the difficulty of disentangling the effect of one pollutant from those of others.

As an alternative to regulating pollutants one at a time — the approach outlined in the CAA Amendments of 1990 — consideration is being given to multi-pollutant strategies that would enable the greatest possible reduction in the public health effects of the mixture of inhaled pollutants.2Exposure to traffic-related pollution generally, for example, has adverse health effects but is not specifically addressed in the CAA.3 Some multi-pollutant strategies have already been introduced. The CASAC has just reviewed a multi-pollutant approach for managing the combined effects of oxides of nitrogen and oxides of sulfur as they are deposited in sensitive aquatic ecosystems.4 More integrated strategies for air-quality management might also improve control of greenhouse gas emissions, which come from the same sources as the criteria pollutants. New research approaches would be needed to support such integrated strategies.5 Ongoing research may lead to more refined indicators for particulate-matter pollution, to replace the current mass-based standard, which includes a mixture of particles from many sources.

Further interpretation or amendment of the CAA may eventually be needed to advance multi-pollutant air-quality management. Revised interpretation can be controversial and subject to legal challenge; amendments have been passed infrequently and cautiously in the past. But the individual-pollutant approach no longer accords as well with our scientific understanding of air pollution and its potential hazards for human and environmental health. More integrative strategies might well address air-quality problems extending from local to global levels. Any future Congressional action on the CAA should be consistent with the spirit of previous amendments, which recognized that U.S. standards for air quality should be grounded in the best available scientific evidence.

Fourth runway may be needed

South China Morning Post – 6 July 2011

Airport Authority figures indicate that proposed third runway may reach full capacity as early as 2029, just six years after coming into service

The HK$136.2 billion it would cost to build a third runway at Chek Lap Kok may only buy six to eight years of growth in traffic for the airport before it is saturated again, according to Airport Authority figures.

In three public forums – the last of which took place on Saturday – to lobby support for the project, officials said the multibillion-dollar investment would cater for the airport’s needs until 2030 and beyond, but did not say how far beyond.

A careful look at the figures provided in the Airport Master Plan 2030 – a blueprint outlining the airport’s development for the next two decades – shows that even using the authority’s “prudent” projection of an average annual growth in air traffic of 3.2 per cent, the runway will be full by 2031. Taking the more “aggressive” prediction of 3.6 per cent, the runway would reach capacity as early as 2029, six years after its opening in 2023. This does not take into account any delay the project may encounter during a construction over 11 years.

“The Airport Authority should tell the public if the third runway can only meet growth for a few years,” said Emily Lau Wai-hing, chairwoman of the Legislative Council finance committee that will determine if the project receives public funding. “Do we need a fourth runway? We should listen to all opinions.”

Hong Kong Dolphin Conservation Society chairman Samuel Hung Ka-yiu said there was simply no more space for a fourth runway.

“It is ridiculous that such a costly project could just meet a few years of growth,” he said. “The third runway is just 1 kilometre from a marine park in Lung Kwu Chau. If they built a fourth runway, the park would have to be removed. How many natural resources can we afford to lose in this expensive game chasing economic growth?”

The third runway would boost the airport’s handling capacity from 68 flights an hour to 102, which translates into 620,000 movements a year. According to the authority’s forecast, air traffic demand will reach 602,000 movements by 2030 based on annual growth of 3.2 per cent. If the growth continues for just another year, aircraft movements will reach 621,264 – already exceeding the capacity of a three-runway system by 1,264 flights.

Under the more robust prediction of 3.6 per cent growth each year the number of aircraft movements will exceed 600,000 by 2028, and over 620,000 by 2029 – one year before the end of a period where growth demand was said to be sustainable.

In fact, the third runway is likely to be saturated even earlier than that.

In the 20 years to 2010, the annual average growth for passenger throughput, cargo throughput and aircraft movements were, respectively, 4.8 per cent, 8.5 per cent and 5.5 per cent – all higher than the rate adopted by the authority in forecasting air traffic for the next 20 years to 2030. Besides, officials appeared to have used a lower base when plotting the growth curve; while aircraft movements reached 316,000 last year, the dot reflecting the number of flights for 2010 was put below the line of 300,000.

An Airport Authority spokesperson said last night that with future air navigation technology and improvements in air traffic management, runway capacity could potentially be stretched further.

“This may increase by about 10 per cent in future if there are enhancements in aircraft or air traffic control or the Pearl River Delta airspace structurer.”

It earlier said Hong Kong will lose more than 100 million passengers and 15 million tonnes of air cargo in the 10 years to 2030 without the third runway. Officials have said they will review the need of a fourth runway in due course.

Emissions from aircraft will grow

The 2 per cent aviation emissions figure Cathay Pacific  Mark Watson cites (“Aviation industry is committed to addressing climate change impact”, June 20) in response to my letter (“Emissions accelerating, not declining”, June 13) differ from the 3-3.5 per cent cited by the International Civil Aviation Organisation (ICAO) website.

The ICAO’s projected aircraft emissions growth of 3-4 per cent per year contrasts with Mr Watson’s planned halving of emissions by 2050. In 38 years, a 3.5 per cent exponential growth will quadruple, not halve, current emissions: 628 million tonnes of carbon dioxide (CO2) annually will become 2,512 million tonnes. Because aircraft engines release CO2, nitrogen oxides (NOx) and particulates into the stratosphere, their impact is amplified. Current contrail-generated cirrus clouds insulate the atmosphere adding an independent warming effect greater than all previous aircraft CO2/NOX emissions since we began flying. Also, the 70 per cent of improvement in aircraft fuel efficiency has already been achieved. To “radically reduce” that remaining 30 per cent of emissions is technically increasingly difficult.

Any future efficiency improvements are offset by the doubling of flights projected by the Airport Authority (advert in this paper on June 21). I quote: “HK’s GDP forecast at compound annual growth rate (CAGR) of 3.4 per cent” (GDP doubles in 20 years); “Mainland’s CAGR at 7 per cent” (an unrealistic quadruple GDP increase over 38 years); “Air traffic demand doubling by 2030”, coincidentally, a 3.5 per cent annualised growth in demand. Where is this growth to come from? Cheap extractable oil, without which these growth projections are unfeasible, is almost exhausted.

If the authority’s growth projections are correct, aircraft emissions will rise exponentially, making climate change a major problem – or peak oil will terminate the 20th century infinite-economic-growth/business-as-usual model, making flying prohibitively expensive, thereby killing demand. Thus, a third runway either adds to climate change or is redundant.

Richard Fielding, Pok Fu Lam

Letters to Editor SCMP

Airport Authority Hong Kong – Online Survey

Airport Authority Hong Kong (AAHK) is consulting the public on the Hong Kong International Airport (HKIA) Master Plan 2030 (MP2030), which outlines the strategic direction of the future development of HKIA, that is, maintaining the existing two-runway system or expanding into a three-runway system, and has commissioned the Social Sciences Research Centre (SSRC) of the University of Hong Kong to independently collect and compile public views. Your opinion is very important and valuable for this consultation. It will only take a few minutes to complete this questionnaire and all information collected will be kept strictly confidential and for collective analysis only. If you have any queries on this survey, you can contact the SSRC at 3921 2600 between 9 am and 6 pm from Monday to Friday.*

MasterPlan 2030 :