Breathing Dust and Soot Raises Risk of Stroke

ANN ARBOR, Michigan, June 2, 2008 - Short-term exposure to low levels of particulate air pollution may increase the risk of stroke or mini-stroke, according to new research conducted in Texas that suggests current exposure standards are not sufficient to protect the public. Stroke is the third leading cause of death in the United States.

The study examined particulate air pollution in the southeast Texas community of Corpus Christi where there is a large petroleum and petrochemical industry presence.

The results showed what the researchers called "borderline significant associations" between same day and previous day exposures to fine particulate matter and risk of ischemic strokes.

Ischemic (is-skeem-ic) stroke occurs when an artery to the brain is blocked.

In the study, researchers identified ischemic strokes and also transient ischemic attacks, or TIA, sometimes called mini strokes, that often lead to a stroke later.

Findings suggest that recent exposure to fine particulate matter may increase the risk of these types of stroke events specifically.

Particulate matter is a combination of fine solids such as dirt, soil dust, pollens, molds, ashes, and soot; and aerosols that are formed in the atmosphere from gaseous combustion by-products such as volatile organic compounds, sulfur dioxide and nitrogen oxides.

Particulate pollution comes from such diverse sources as factory and utility smokestacks, vehicle exhaust, wood burning, mining, construction activity, and agriculture.

"The vast majority of the public is exposed to ambient air pollution at the levels observed in this community or greater every day, suggesting a potentially large public health impact," said Lynda Lisabeth, lead author and assistant professor in the University of Michigan School of Public Health, where the research is based.

Despite the fossil fuel industry in the area, fine particulate matter exposures were low relative to other regions of the country, the researchers said probably because of the proximity to the coast and prevailing wind patterns.

Lisabeth stressed that the association requires further study in other areas with varying climates and alternative study designs.

Ischemic stroke is by far the most common kind of stroke, accounting for about 88 percent of all strokes. Stroke can affect people of all ages, including children.

Many people with ischemic strokes are 60 or older, and the risk of stroke increases as people age. At each age, stroke is more common in men than women, and it is more common among African-Americans than white Americans.

For this study, researchers looked at data from the Brain Attack Surveillance in Corpus Christi Project, a population-based stroke surveillance project designed to capture all strokes in Nueces County, Texas.

Ischemic stroke and TIA cases between 2001 and 2005 were identified using trained staff and later verified by neurologists.

Daily historical air pollutant and meteorological data were obtained for the same time period from the Texas Commission on Environmental Quality's Monitoring Operations database.

Data on fine particulate matter and ozone from a centrally located monitor in Corpus Christi located upwind of the local industrial facilities was used in the study.

The majority of stroke and TIA cases were found to be located upwind of local chemical plants and refineries.

Some research has shown that particulate air pollution is associated with acute artery vasoconstriction and with increased thickening of the blood, which may enhance the potential for blood clots.

Similar associations were also seen with ozone, another type of air pollution.

This study confirms earlier research showing that exposure to fine particle matter air pollution increases a person's risk for hospital admission for cardiovascular and respiratory diseases.

The study, "Ambient Air Pollution and Risk of Ischemic Stroke and TIA," will be published in the July 2008 issue of Annals of Neurology http://www.interscience.wiley.com/, the official journal of the American Neurological Association.

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Particulates Cause More Premature Deaths than Previously Thought

More premature deaths than previously thought from particles in vehicle exhaust New research reveals significant new information

The California Air Resources Board was presented with research today showing long-term exposures to fine particle pollution pose a greater health threat than previously estimated.

Annually, 14,000 to 24,000 premature deaths are estimated to be associated with exposures to PM2.5, a mix of microscopic particles less than 2.5 microns in size. A majority of these deaths occur in highly populated areas around the state, including the South Coast, San Joaquin Valley and San Francisco Bay air basins.

"Particle pollution is a silent killer," said ARB Chairman Mary D. Nichols. "We must work even harder to cut these life-shortening emissions by further addressing pollution sources head-on."
Particulate matter (PM) is a complex blend of substances ranging from dry solid fragments, solid-cores fragments with liquid coatings, and small droplets of liquid. These particles vary in shape, size and chemical composition, and may include metals, soot, soil and dust.

At the request of the board in 2006, ARB researchers carefully reviewed all scientific studies on the subject and consulted with health scientists. While exposures to particulate matter have long been known as a serious health threat, new information suggests that the pollutant is even more toxic than previously thought.

Hospitalizations, emergency room visits and doctor visits for respiratory illnesses or heart disease have been associated with PM2.5 exposure. Other studies suggest that PM2.5 exposure may influence asthma symptoms and acute and chronic bronchitis.

Children, the elderly and people with pre-existing chronic disease are most at risk of experiencing adverse health effects from PM2.5 exposure. Even small increases in PM2.5 exposures may increase health risks.

Major contributors to PM2.5 include trucks, passenger cars, off-road equipment, electric power generation and industrial processes, residential wood burning, and forest and agricultural burning. All combustion processes generally produce PM2.5.

While the new data reveals a greater threat from PM2.5, the state's previous efforts to reduce emissions throughout the state have been successful. The ARB in coordination with the 35 air districts throughout the state continues to develop and implement strategies of aggressive air pollution control. These measures have been so effective for the last two decades that PM exposures have been reduced in California's major populated areas. Since the official year-round monitoring of ambient PM2.5 began in 1999, concentrations have decreased 30 percent across California, most notably in the South Coast and the San Joaquin Valley regions.

Additionally, in 2000 ARB adopted an aggressive risk reduction plan that targets all diesel PM sources in California. As part of the plan, cleaner diesel fuels and new diesel engines (both on-road and off-road) have been developed. In concert with regulations aimed at requiring cleaner new engines, other regulations have been adopted to address diesel engines already on the road, including those in waste collection vehicles, transit fleet, school buses, stationary engines, transport refrigeration units and portable engines. Later this year, ARB will consider rules to significantly cut diesel particulate emissions from private truck fleets.

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When it Comes to Air Pollution, What You Can't See Can Hurt You

Research presented at American Society of Hypertension's Twenty Third Annual Scientific Meeting and Exposition (ASH 2008) shows that even a few hours of exposure to particulate matter (PM), which is not ozone but a component of air pollution emitted from power plants, factories and motor vehicles, among other sources, is responsible for rapidly raising blood pressure and can impair blood vessel function in certain situations within 24 hours. These effects may explain why air pollution can trigger a large host of CV events including heart attack, heart failure and stroke.

"Not everyone is equally at risk to the effects of poor air quality," said Robert Brook, Assistant Professor of Medicine of the Division of Cardiovascular Medicine at the University of Michigan. "Yet, as traffic worsens and millions of vulnerable people are exposed to PM, it is incumbent upon us to understand how and why people are affected so that we can take steps to limit our personal exposure – and consider making broader changes to the public agenda to control air pollution."

PM is the 13th cause of mortality worldwide, but until now, the explanation underlying this association remains incompletely understood.

In their study, researchers designed two randomized, double-blind exposure experiments – one in downtown Toronto and one in Ann Arbor, Michigan – to investigate how PM raises blood pressure in healthy adults, aged 18 to 50, and what air pollution constituents are responsible. In Toronto, researchers compared the effect on blood pressure and blood vessel functions among 30 adults for two hours in four different exposure situations: concentrated ambient PM (CAPS alone), CAPS and ozone, ozone alone or filtered air. Results showed that short term exposure to air pollution that contains PM (CAP or CAP and ozone) – but not ozone alone – significantly raised diastolic blood pressure by 3.6 mm Hg on average (a significant difference from filtered air), and only during the exposure period of two hours. Blood vessel function was impaired 24 hours after all exposures containing PM, but not ozone alone, and not immediately after any exposure type (within five minutes).

In Ann Arbor, researchers compared the effect of CAP and ozone in 50 adults pre-treated with the anti-oxidant vitamin C, a blocker of the vasoconstrictor hormone endothelin (bosentan) and placebo. Diastolic blood pressure increased to a similar degree, between 2.5 and 4.0 mm Hg, during all exposure types. Blood vessel function was not impaired at any time point after all exposures, and blood pressure returned to normal within 10 minutes after exposure.

Results confirm that it is PM and not ozone that is responsible for the rapid raise in diastolic blood pressure and that the pro-hypertensive response occurs only during the actual inhalation of the particles. The very rapid and transient nature of the increase in blood pressure, and the fact that pre-treatment with vitamin C did not block the response, suggest that a sudden increased in sympathetic nervous system activity is the most like cause.

Additionally, the study confirmed that PM does impair blood vessel function one day following exposure. But since this response occurred only in Toronto, the composition of PM or its source may likely play a role in determining the health response.

"These findings are a springboard for further study that will specifically determine how the sympathetic nervous system responds and to what types of particles in air pollution," said Dr. Brook. "But this glimpse helps us determine the triggers behind a range of CV events – some deadly. Learning how this dangerous cascade starts can help the medical and public health community make advances toward limiting their impact in the future."

About the American Society of HypertensionThe American Society of Hypertension (ASH) is the largest U.S. professional organization of scientific investigators and healthcare professionals committed to eliminating hypertension and its consequences. ASH is dedicated to promoting strategies to prevent hypertension and to improving the care of patients with hypertension and associated disorders. The Society serves as a scientific forum that bridges current hypertension research with effective clinical treatment strategies for patients.

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ARB Approves State Strategy to Improve California Air Quality

Drastic emissions cuts expected in next decade

The Air Resources Board today approved an ambitious, multi-faceted plan to significantly improve air quality throughout the state, along with announcing new measures on two regional plans geared toward meeting federally mandated emissions standards and deadlines for the South Coast and San Joaquin Valley.

"The 2007 State Implementation Plan shows how California expects to attain clean air through a combination of innovative and cost-effective measures," said Mary Nichols, ARB Chair. "With this vital document in place, we have a roadmap to the future that will keep us on track to meet our air quality goals."

In addition to the State strategy, the ARB approved a plan submitted by the South Coast Air Quality Management District to hasten emissions reductions through cooperative measures to be implemented by both ARB and the SCAQMD. This plan, which will reduce emissions of the smog precursor oxides of nitrogen (NOx) by more than 500 tons per day by 2014, now becomes part of the State SIP, which will be forwarded to the U.S. EPA for final approval. NOx reacts with sunlight to form ozone, a key ingredient of smog.

Also approved was an expedited strategy to improve ozone air quality in the San Joaquin Valley some 90 percent by 2018 in terms of the federal standard. For example, the strategy calls for ARB to clean up emissions from farm equipment, and to partner with the San Joaquin Valley Air Pollution Control District to accelerate the timeline of the recently passed off-road construction rules by offering financial incentives to Valley businesses aimed at getting older, dirtier engines retrofitted or replaced.

Both the South Coast and San Joaquin plans focus on efforts to meet federal deadlines specifically for ground-level ozone and particulate matter (PM2.5) emissions. Target dates for compliance are 2014 for PM2.5, and 2023 for ozone in areas designated by the EPA as having "extreme" air pollution such as the San Joaquin Valley and South Coast Air Basin.

While the federal ozone attainment date for the San Joaquin Valley remains 2023, ARB's new proposal this week will fast-track efforts to get 90 percent compliance by 2018. The last 10 percent will require new technologies that are not readily available now.

Because ARB scientists determined that reducing emissions of one pollutant, oxides of nitrogen (NOx), is the most beneficial in reducing levels of both ozone and PM2.5, the state plan focuses on curbing pollution from the sources that produce nearly 90 percent of the state's NOx. These sources include cars, heavy duty trucks, large off-road equipment, ships and locomotives.

The State's cleanup strategy includes the following measures:
* Clean-up of In-Use Heavy Duty Trucks. This critical regulation, to be presented to the Board in mid- 2008, will modernize diesel trucks and reduce emissions by requiring replacement or cleanup of the dirtiest trucks on the road, and will also include a program for out-of-state trucks doing business in California.

* Targeting Goods Movement Sources. A myriad of measures take aim at reducing emissions from ships, trucks, harbor craft and other sources. In October, ARB will consider requiring owners of commercial harbor craft to either replace old engines with newer, cleaner versions or add control technologies to clean up exhaust. In December, ARB will consider a regulation to provide alternative power supplies at ports so that ship auxiliary engines can avoid using diesel power while at dock.Also on the December agenda is a measure requiring retrofit or replacement of older heavy-duty diesel trucks that service ports.

* Targeting Off-Road Sources. In July, the Board approved this measure which regulates construction and other industrial equipment, establishing fleet average emission limits and requiring older, dirtier engines to be replaced by current models or retrofitted with emission control devices.Agricultural equipment will also be modernized and cleaned up, with the Board expected to consider regulation in 2009.

"California industry has already reduced NOx emissions at a faster pace than anywhere in the world over the last 40 years by introducing cleaner technologies," said ARB Chair Nichols."Following this strategy will mean progress at an unprecedented rate. It's what we need to do to protect public health."

The SIP approved today includes both rules that have been adopted already and rules that are proposed and scheduled for public input.

Both ozone and fine PM can have significant health impacts.Ozone contributes to respiratory ailments and asthma, and can cause premature death in elderly patients with lung disease. It is a product of a photochemical process involving the sun's energy and ozone precursors, such as hydrocarbons and oxides of nitrogen (NOx). Exposure to fine PM exacerbates respiratory and cardiovascular ailments and is responsible for approximately 8,200 premature deaths per year in the state.

The Air Resources Board is a department of the California Environmental Protection Agency. ARB's mission is to promote and protect public health, welfare, and ecological resources through effective reduction of air pollutants while recognizing and considering effects on the economy. The ARB oversees all air pollution control efforts in California to attain and maintain health based air quality standards.

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High Pollution Affecting Children in Mexico City

According to researchers in Mexico, children who are chronically exposed to higher levels of air pollution show marked deficiencies in lung growth and function.

"Our study revealed significant deficits in lung function growth in children with long-term exposure to air pollutants,” wrote Isabelle Romieu, M.D., M.P.H., lead author of the study. "In addition to the important impact of lung health, early lung deficits may increase the risk of developing chronic obstructive lung disease later in life, as well as cardiovascular morbidity and general mortality.

These conclusions are the result of a three-year, multi-site prospective study that measured lung function growth in 3,170 eight-year-old children at 39 schools in Mexico City and analyzed it with respect to the children’s exposure to common urban pollutants: ozone (O3), nitrogen dioxide (NO2), and particulate matter under 10 μm (PM10).

Dr. Romieu, of the Instituto Nacional de Salud Publico in Mexico, and eight colleagues reported their findings in the second issue for August of the American Journal of Respiratory and Critical Care Medicine, published by the American Thoracic Society.

Previous studies have found that short-term exposure to pollutants is associated with acute but reversible deficits in lung function, but the effects of long-term exposure, like that experienced by residents of heavily polluted urban environments, had not been conclusively characterized.

Although all measurements of lung function increased over time, the researchers found that higher exposure to O3, NO2 and PM10 was significantly associated with growth deficits.

“At the beginning of the study and at each phase of follow-up, children exposed to lower O3 and PM10 concentrations had better lung function values that children exposed to higher concentrations,” wrote the researchers.

The study could not determine the mechanism by which pollutants change lung growth, but other studies have found differences in lung morphology related to O3 exposure, and suggested that chronic exposure to PM and O3 may be associated with small airway disease.

Recently, oxidative stress from oxidant compounds, including O3, NO2 and PM has been identified as a potential cause of an inflammatory response, which could then lead to chronic lung damage. The reversibility of the damage is unclear, but the authors note that previous studies have reported long-term deficits in lung function associated with air pollutants.

“Although we could not identify specific sources [of the pollutants], the effect is likely to be due to vehicular exhaust,” wrote the researchers, concluding that “there is a clear need for stricter air pollution measures in Mexico City to protect lung growth in children living there.”

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NIWA Expands Urban Air Quality Team

NIWA Media Release 8 January 2007

NIWA expands team to meet challenge of poor urban air quality

For a country with a relatively low population density, New Zealand’s air quality can be very poor. The most significant concern is wintertime air pollution in urban centres, where emissions from domestic solid fuel heaters generate high ambient concentrations of PM10 (Particulate Matter with a diameter of ten micrometres or less). Vehicle pollution is also an important source in the larger cities. Recent research has estimated that as many as 900 people may die prematurely each year in New Zealand from the effects of air pollution and that the cost to the New Zealand taxpayer of the health effects of air pollution is greater than six hundred million dollars per year.

The National Institute of Water & Atmospheric Research (NIWA) is expanding its urban air quality team. The group carries out research into the processes controlling air pollution in urban environments and investigates methods of managing or mitigating its effects. We also provide air quality monitoring and consultancy services to government and industry throughout NZ.

Group manager, Dr Guy Coulson, says three new staff will substantially boost NIWA’s capacity to conduct scientific research and commercial consultancy work. The group will now have six scientists based in Auckland, Wellington, and Christchurch, supported by a three-person strong technical team based in Auckland. The team is Jeff Bluett, Tom Clarkson, and Guy Coulson with newcomers Perry Davy, Ian Longley, and Gustavo Olivares, supported by Lou Reddish, Sally Gray, and Jeremy Hunt.