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A recent post (Air Pollution Can Kill You) discussed recent research that found that air pollution is linked to an overall increase in death rates, especially cardiovascular disease. But how many deaths each year are linked to air pollution? Recent research suggests that outdoor air pollution, mostly by fine particulate matter with a diameter smaller than 2.5 micrometers (PM2.5), leads to 3.3 million premature deaths per year worldwide, predominantly in Asia. The number one cause  worldwide is residential energy use such as heating and cooking, (India ,China, and the developing world).

But surprisingly agriculture or farming is number 2 worldwide. How can that be? Well, farms produce ammonia from fertilizer and animal waste. That ammonia then combines with sulfates from coal-fired power plants and nitrates from vehicle exhaust to form the soot particles that are the big air pollution killers. The United States had about 54,905 deaths in 2010 from soot and smog. Power plants and traffic (vehicle emissions) are big sources of the air pollution linked to deaths in the USA. From Medical Xpress:

Millions of premature deaths tied to air pollution

Outdoor air pollution leads to more than 3 million premature deaths per year, primarily in Asia, according to a letter published online Sept. 16 in Nature.

Johannes Lelieveld, Ph.D., from the Max Planck Institute for Chemistry in Germany, and colleagues used a global atmospheric chemistry model to investigate the link between premature mortality and seven emission source categories in urban and rural environments. The researchers found that outdoor air pollution, mostly by fine particulate matter with a diameter smaller than 2.5 micrometers (PM2.5), leads to 3.3 million premature deaths per year worldwide, predominantly in Asia. The largest impact on premature mortality globally comes from residential energy use such as heating and cooking, prevalent in India and China. In the United States, emissions from traffic and power generation are important. Agricultural emissions make the largest relative contribution to PM2.5 in the eastern United States, Europe, Russia, and East Asia, with the estimate of overall health impact depending on assumptions regarding particle toxicity. 

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Another study finding negative health effects from air pollution. This year I've posted several studies that found negative effects on the brain (and even cognition) from air pollution for people of all ages. Now this latest study found that in areas with air pollution, long-term exposure to outdoor fine particulate matter (PM2.5),which are fine particles in the air, are linked to an overall increase in risk of death, especially due to cardiovascular disease. The fine particles in the air contribute to the development of potentially fatal heart and lung diseases because they slip past the body's defenses and can be absorbed deep into the lungs and bloodstream. They are not sneezed or coughed out the way larger natural particles, like airborne soil and sand, are removed from the body's airways. From Science Daily:

Link between air pollution, increased deaths and increased deaths from heart disease affirmed

In what is believed to be the largest, most detailed study of its kind in the United States, scientists at NYU Langone Medical Center and elsewhere have confirmed that tiny chemical particles in the air we breathe are linked to an overall increase in risk of death. The researchers say this kind of air pollution involves particles so small they are invisible to the human eye (at less than one ten-thousandth of an inch in diameter, or no more than 2.5 micrometers across).

In a report on the findings, published in the journal Environmental Health Perspectives online Sept. 15, the scientists conclude that even minuscule increases in the amount of these particles (by 10 micrograms per cubic meter of air, for example) lead to an overall increased risk of death from all causes by 3 percent -- and roughly a 10 percent increase in risk of death due to heart disease. For nonsmokers, the risk increase rises to 27 percent in cases of death due to respiratory disease.

"Our data add to a growing body of evidence that particulate matter is really harmful to health, increasing overall mortality, mostly deaths from cardiovascular disease, as well as deaths from respiratory disease in nonsmokers," says lead study investigator and health epidemiologist George Thurston, ScD, a professor of population health and environmental medicine at NYU Langone. "Our study is particularly notable because all the data used in our analysis comes from government- and independently held sources."

According to Thurston, fine particles can contribute to the development of potentially fatal heart and lung diseases because they slip past the body's defenses and can be absorbed deep into the lungs and bloodstream. They are not sneezed or coughed out the way larger natural particles, like airborne soil and sand, are removed from the body's airways. Moreover, Thurston says, fine particles are usually made of harmful chemicals such as arsenic, selenium, and mercury, and can also transport gaseous pollutants, including sulfur and nitrogen oxides, with them into the lungs.

For their research, Thurston and his colleagues evaluated data from a detailed health and diet survey conducted by the National Institutes of Health (NIH) and the American Association of Retired Persons (AARP). The NIH-AARP study involved 566,000 male and female volunteers, ages 50 to 71, from California, Florida, Louisiana, New Jersey, North Carolina, Pennsylvania, and the metropolitan areas of Atlanta and Detroit. Analyzing information gathered about the participants between 2000 and 2009,....

Indeed, the team did not find any significant difference in the effect of particulate matter exposure between different sexes or age groups or by level of education. The researchers also noted that limiting the analysis to only the state of California, which has the most rigorous controls on air pollution, did not produce a different overall level of risk; instead, they found the same association between particulate matter exposure and increase in risk of death from all nonaccidental causes and from cardiovascular disease.

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Several recent studies have found that constant exposure to high levels of air pollution has negative effects on the brain. The last post described negative effects on the gray matter in brains (resulting in smaller brain volumes) of elderly women from air pollution, but this study found negative effects (lower grade point averages) in young children from high air pollution. From Environmental Health News:

Bad air means lower grade point averages in Texas

Fourth and fifth graders in El Paso, Texas, are more likely to have lower grade point averages if heavily exposed to contaminated air at home, according to a new study.It bolsters a growing body of evidence that air pollution can impair success in school.

They found that for all types of air pollution sources, more exposure corresponded with lower grade point averages. Only one type of pollution—point sources such as factories—was not significantly linked to lower grade point averages.University of Texas at El Paso researchers analyzed the grade point averages of 1,895 children and, using their home location, estimated their exposure to air toxics—such as benzene, arsenic, lead, mercury, hydrochloric acid, toluene, vinyl bromide, xylenes, and diesel particulate matter—using federal data.

“Effects appear to be insidious, since they are mild, unlikely to be perceived, and, hence, unlikely to be addressed in any way … seemingly trivial effects on children’s development may translate into substantial impacts throughout the life course in terms of physical and mental health and personal success,” the authors wrote.The researchers did control for some other things that can affect children’s grades such as poverty, mother’s age, education and ability to speak English, and the child’s race and sex.

Still, the study doesn’t prove that dirty air makes kids do worse in school. It does, however, suggest children’s developing bodies are more susceptible to air pollution, which can harm their respiratory systems and brain.Air pollution might hamper kids’ grades via two primary ways: Illnesses, mostly respiratory, that would make them miss school, and developmental problems resulting from long-term exposure, said Sara Grineski, an associate professor of sociology at The University of Texas at El Paso and co-author of the new study.

Others have found similar links between air pollution and academic performance. Three months ago Columbia University's Perera and colleagues reported that New York City children born to mothers in poverty and exposed to certain air toxics during pregnancy had lower IQs.  Perera, tracking the mothers and children since before birth, said the pollution exposure prior to birth is more strongly linked to learning and behavioral problems. 

In the current study it’s unclear if the children were exposed in their mothers’ womb—an exposure window that is critical to brain development, Perera said....Other studies support this—in February Calderón-Garcidueñas and colleagues reported Mexico City smog was linked to impaired short-term memory and IQ in children.

The city is more than 80 percent Hispanic....Previous studies have shown that El Paso’s minorities are disproportionately impacted by toxics, Grineski said. The city of 675,000 is one of the worst when it comes to particulate matter—a mix of substances emitted by combustion sources, including cars, trucks, industrial plants and wood burning—especially coarse particulates, PM10, those between 2.5 and 10 micrometers (from about 25 to 100 times thinner than a human hair, according to the EPA). El Paso’s 24-hour PM10 average is about 233 micrograms per cubic meter of air, according to the latest EPA data from 2013, which was eighth highest among more than 500 U.S. cities. El Paso, along with Laredo, has the highest carbon monoxide levels in Texas.

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Several recent studies found that air pollution has a negative effect on the brain. This study of elderly women in North Carolina found that long-term exposure to higher levels of air pollution (specifically fine particulate matter smaller than 2.5 micrometers (called PM2.5) resulted in smaller brain volumes (especially the brain's white matter). They studied elderly women (aged 71 to 89), but the findings should be of concern to everyone exposed to high levels of air pollution.  White matter connects brain regions (with nerve fibers that pass signals throughout the brain) and determines how information is processed in the brain. The researchers pointed out that other recent studies reported that high air pollution is linked to cognitive decline and accelerated brain aging. From Futurity:

AIR POLLUTION MAY SHRINK BRAIN’S WHITE MATTER

Exposure to air pollution may have a negative impact on how the brain’s white matter ages. Older women who lived in geographic locations with higher levels of fine particulate matter in ambient air had significantly smaller white matter volumes across a wide range of brain areas, new research shows.

Fine particulate matter is smaller than 2.5 micrometers and is known as PM2.5, a form of pollution that easily enters the lungs and possibly the bloodstream. White matter connects brain regions and determines how information is processed in the brain....“Our study provides convincing evidence that several parts of the aging brain, especially the white matter, are an important target of neurotoxic effects induced by long-term exposure to fine particles in the air.”

The study found that older women ages 71 to 89 who had lived in places with greater PM2.5 exposures had significantly smaller volumes of white matter and that this could not be explained by the geographic region where they lived, their race or ethnic background, socioeconomic status, lifestyle, or medical conditions that may also influence brain volumes.

The researchers performed brain magnetic resonance imaging scans of 1,403 women who are part of the Women’s Health Initiative Memory Study (WHIMS), a nationwide report based at Wake Forest Baptist Medical Center in Winston-Salem, NC. The researchers also used residential histories and air monitoring data to estimate the participants’ exposure to air pollution in the previous six to seven years.

White matter contains nerve fibers and connects brain regions with each other by traveling deep within and passing nerve signals throughout the brain. Gray matter is primarily composed of neuronal cell bodies, dendrites, glial cells, and capillaries. The study did not find impacts from exposure to air pollution in participants’ gray matter.

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Another good reason to breastfeed. Exposure to pollutants like nitrogen dioxide and airborne particles can cause negative effects on motor and mental development in infants, but a new study says those effects are countered in babies who are breast-fed for at least 4 months by their mothers. Researchers in Spain began monitoring rural, pregnant women in 2006 and analyzed samples from 638 women and their infants at 15 months. They reported that babies who are breast-fed did not suffer from the potentially harmful developmental impact of PM2.5 (pollution particle matter) and NO2 (nitrogen dioxide). From Science Daily:

Breastfeeding protects against environmental pollution

Living in a city with a high level of vehicle traffic or close to a steel works means living with two intense sources of environmental pollution. However, a study conducted by the UPV/EHU researcher Aitana Lertxundi indicates that the harmful effect of PM2.5 pollution particle matter and nitrogen dioxide (NO2) disappears in breastfed babies during the first four months of life. According to the results of the research, breastfeeding plays a protective role in the presence of these two atmospheric pollutants.

Lertxundi's study focusses on the repercussions on motor and mental development during the first years of life caused by exposure to the PM2.5 and NO2 atmospheric pollutants .... "In the fetal phase the central nervous system is being formed and lacks sufficient detoxification mechanisms to eliminate the toxins that build up," pointed out Aitana Lertxundi.

The PM2.5 particles measure less than 2.5 micra, in other words, they are four times thinner that a single hair and are suspended in the air. As they are so small they can easily penetrate the body and as they weigh so little they can spread without any difficulty through the air and can move far away from the initial emission source. The composition of these neurotoxic particles depends on the emission sources in the area. The INMA Gipuzkoa area under study has a high presence of neurotoxic particle matter made up of lead, arsenic and manganese from industrial activity and traffic. In comparison with urban averages where the main source of pollution is traffic, the concentration is lower.

One result of the study is that the existence of an inverse relationship has been detected between exposure to pollution particle matter and the motor development of babies. In this respect, the researcher highlights the fact that "these indices display an alteration with respect to the average and, even if they are not worrying, they are significant in that they reveal the relationship existing between air quality and motor development." The analysis of the data also shows that neither the PM2.5 particle matter nor the NO2 exert a harmful effect on babies breastfed on mother's milk for at least four months.

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Another study finding negative effects of air pollution - this time high levels of traffic-related air pollution is linked to slower cognitive development among 7 to 10 year old children in Barcelona, Spain. From Science Daily:

Air pollution linked to slower cognitive development in children

Attendance at schools exposed to high levels of traffic-related air pollution is linked to slower cognitive development among 7- to 10-year-old children in Barcelona, according to a new study.

The researchers measured three cognitive outcomes (working memory, superior working memory, and attentiveness) every 3 months over a 12-month period in 2715 primary school children attending 39 schools. By comparing the development of these cognitive outcomes in the children attending schools where exposure to air pollution was high to those children attending a school with a similar socio-economic index where exposure to pollution was low, they found that the increase in cognitive development over time among children attending highly polluted schools was less than among children attending paired lowly polluted schools, even after adjusting for additional factors that affect cognitive development.

Thus, for example, there was an 11.5% 12-month increase in working memory at the lowly polluted schools but only a 7.4% 12-month increase in working memory at the highly polluted schools. These results were confirmed using direct measurements of traffic related pollutants at schools.

The findings suggest that the developing brain may be vulnerable to traffic-related air pollution well into middle childhood, a conclusion that has implications for the design of air pollution regulations and for the location of new schools. While the authors controlled for socioeconomic factors, the accuracy of these findings may be limited by residual confounding, that is, the children attending schools where traffic-related pollution is high might have shared other unknown characteristics that affected their cognitive development.

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Long-term air pollution can cause damage to the brain: covert brain infarcts ("silent strokes") and smaller brain volume (equal to one year of brain aging).

The authors of a study looking at 900 men in the Boston area concluded that, on average, participants who lived in more polluted areas had the brain volume of someone 1 year older vs participants who lived in less polluted areas, and they also had a 46% higher risk for silent strokes. While the mechanisms of how air pollution may affect brain aging is unclear, the researchers think that inflammation resulting from the deposit of fine particles in the lungs is important. From Science Daily:

Long-term exposure to air pollution may pose risk to brain structure, cognitive functions

Air pollution, even at moderate levels, has long been recognized as a factor in raising the risk of stroke. A new study led by scientists from Beth Israel Deaconess Medical Center and Boston University School of Medicine suggests that long-term exposure can cause damage to brain structures and impair cognitive function in middle-aged and older adults. 

Writing in the May 2015 issue of Stroke, researchers who studied more than 900 participants of the Framingham Heart Study found evidence of smaller brain structure and of covert brain infarcts, a type of "silent" ischemic stroke resulting from a blockage in the blood vessels supplying the brain.

The study evaluated how far participants lived from major roadways and used satellite imagery to assess prolonged exposure to ambient fine particulate matter, particles with a diameter of 2.5 millionth of a meter, referred to as PM2.5. These particles come from a variety of sources, including power plants, factories, trucks and automobiles and the burning of wood. They can travel deeply into the lungs and have been associated in other studies with increased numbers of hospital admissions for cardiovascular events such as heart attacks and strokes.

Study participants were at least 60 years old and were free of dementia and stroke. The evaluation included total cerebral brain volume, a marker of age-associated brain atrophy; hippocampal volume, which reflect changes in the area of the brain that controls memory; white matter hyperintensity volume, which can be used as a measure of pathology and aging; and covert brain infarcts.

The study found that an increase of only 2µg per cubic meter in PM2.5, a range commonly observed across metropolitan regions in New England and New York, was associated with being more likely to have covert brain infarcts and smaller cerebral brain volume, equivalent to approximately one year of brain aging...."This is concerning since we know that silent strokes increase the risk of overt strokes and of developing dementia, walking problems and depression."

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Scientists warn about endocrine disruption from 4 common chemicals in an analysis just released. This is absolutely depressing because the 4 chemicals (benzene, toluene, ethylbenzene, xylene) are so pervasive in indoor air. Especially that at levels considered "safe" by the EPA there may be disruption of our hormones (endocrine systems).

Of course the 4 chemicals are already known to have health effects on the human body other than what is discussed in this study. For example, toluene has a number of central nervous system effects. The EPA says toluene , which is found in highest concentrations in indoor air from the use of common household products (paints, paint thinners, adhesives, synthetic fragrances, and nail polish). Outside - the biggest source of toluene is from automobile emissions.

Some ways to lower exposure to these 4 chemicals: Read product labels. When using a product that says to use with proper ventilation - open the windows and let the room ventilate!  Don't smoke. (For example: the EPA says tobacco smoke contains benzene and accounts for nearly half the national exposure to benzene) The study researchers themselves said the EPA should be paying more attention to these air contaminants. I read this at Scientific American, but the following excerpts are from EHN.

From EHN: Scientists warn of hormone impacts from benzene, xylene, other common solvents.

Four chemicals present both inside and outside homes might disrupt our endocrine systems at levels considered safe by the U.S. Environmental Protection Agency, according to an analysis released today. ...continue reading "More Problems With Four Common Chemicals"

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Two studies that found a link with air pollution and health effects.The first found a narrowing of the carotid arteries (that bring blood to brain). This narrowing (stenosis) occurs prior to strokes. While this could be explained by other factors (for example, by especially poor diets or cigarette smoking), the link between high air pollution and heart attacks and strokes has been noted since the 1950s. From Medical Xpress:

Pollution levels linked to stroke-related narrowing of arteries

Air pollution has been linked to a dangerous narrowing of neck arteries that occurs prior to strokes, according to researchers at NYU Langone Medical Center. The scientists analyzed medical test records for more than 300,000 people living in New York, New Jersey or Connecticut. They found that people living in zip codes with the highest average levels of fine-particulate-matter pollution were significantly more likely to show signs of narrowing (stenosis) in their internal carotid arteries, compared to those living in zip codes with the lowest pollution levels.

Fine particulate matter pollutants, also called "PM 2.5 pollutants," are particulates with diameters less than 2.5 millionths of a meter. They are mostly by-products of combustion engines and burning wood. "We spend a lot of time thinking about traditional risk factors for stroke such as high blood pressure, cholesterol, diabetes and smoking—but our data underscore the possibility that everyday air pollution may also pose a significant stroke risk," said senior investigator Jeffrey S. Berger, MD, an assistant professor in NYU Langone Medical Center in the Department of Medicine, Leon H. Charney Division of Cardiology.

Medical researchers have noticed since the 1950s that episodes of high air pollution can bring temporary jumps in local heart attack and stroke cases. More recent studies have linked heart attack and stroke risks to long-term pollution exposures as well, including PM 2.5 exposures.

The two internal carotid arteries are situated on either side of the neck and provide most of the brain's blood supply. Strokes often result when accumulated plaque breaks off from a narrowed section of an internal carotid artery and blocks smaller vessels in the brain.

In the study, the carotid narrowing data came from vascular ultrasound tests performed on 307,444 tri-state area residents during 2003-2008 by Life Line Screening, a leading community-based health screening company focused on evaluating risk factors for vascular disease...The researchers' analysis showed that subjects in the top fourth of tri-state zip codes, ranked by average PM 2.5 levels, were about 24 percent more likely than those in the bottom quarter to have shown signs of stenosis—defined as a narrowing by at least half—in either internal carotid artery.

"Our study was a population study, so it can't establish cause and effect, but it certainly suggests the hypothesis that lowering pollution levels would reduce the incidence of carotid artery stenosis and stroke," says Dr. Newman. Scientists aren't yet sure how air pollution contributes to vascular disease. Studies have indicated that it may do so in part by causing adverse chemical changes to cholesterol in the blood, by promoting inflammation, and by making blood platelets more likely to form clots."

It has long been known that diesel exhaust has negative health effects. From Science Daily:

Researchers uncover a mechanism linking inhaled diesel pollution and respiratory distress

Researchers have, for the first time, shown how exhaust pollution from diesel engines is able to affect nerves within the lung...Diesel exhaust is a significant component of urban air pollution, containing a complicated mixture of gases and airborne particles. "Studies have shown that exposure to these diesel particles is associated with harmful health effects," says Mr. Robinson. "These particles are very small -- down to 20 nanometres in diameter -- and are therefore not only invisible to the naked eye, but can penetrate deep into the lungs.

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Air pollution is harmful on so many levels for all of us, (See recent Dec.post on harmful air pollution effects on pregnancy.) From Reuters Health:

Heart experts warn of air pollution dangers

Air pollution should be one of the avoidable heart risk factors - just like smoking and excess fat - that doctors warn patients to steer clear of, according to a new statement from 20 heart experts.

Citing pollution’s heavy toll on cardiovascular health, the panel urges people to take steps to protect themselves from breathing heavy traffic fumes or industrial air pollution whenever possible, and public officials to pass laws to reduce air pollution.Air pollution causes more than 3 million deaths worldwide each year and causes 3.1 percent of all cases of disability, Storey and his coauthors write in the European Heart Journal.

Air pollution is also ninth most important on a list of modifiable heart-disease risk factors - ranking above low physical activity, high-salt diet, high cholesterol and drug use, the authors point out.

Although gaseous air pollutants can be dangerous too, Storey said, airborne particles are the biggest contributor to cardiovascular disease because they cause inflammation of the lungs and enter the circulation, inflaming blood vessels, provoking clots and causing heart rhythm disturbances.

Particulate matter includes coarse particles from road dust, construction work and industrial emissions and fine particles from traffic, power plants and industrial and residential burning of oil, coal or wood for heating. The bulk of particulate air pollution is made up of these fine particles, known as PM2.5, that are less than 2.5 micrometers - about one fifth the size of visible dust. In 2013, the U.S. Environmental Protection Agency lowered the 24-hour exposure limit to an average of 12 micrograms.

European studies have found that PM2.5 levels are often markedly higher near heavy traffic zones compared to elsewhere in the same city, and that the levels can more than double during rush hours, according to the position statement.

Some of the authors’ advice for people to protect themselves is as simple as walking, cycling and using public transportation instead of driving cars, and exercising in parks or gardens, rather than near busy roads. And everyone should avoid being outside when pollution is highest, though this is especially important for infants, elderly and people with heart problems, the authors say.People who live in heavily polluted areas should also consider ventilation systems with filtration in their homes, since a large portion of outdoor pollution can penetrate buildings.

The use of fossil fuels for heating and energy should also be decreased, according to the statement.

Studies have shown even short-term exposure to high PM2.5 levels increases deaths from heart disease and respiratory disease, and that people living in places with high PM2.5 have an 11 percent greater risk of dying from heart attacks, strokes and heart failure than those who live in cleaner areas.