Ozone Air Pollution Linked To US Deaths, Even At Levels Below Current Safety Standards

MedicalResearch.com Interview with:
Qian Di, M.S, Doctoral Student
Department of Environmental Health and
Francesca Dominici, Ph.D.
Principal Investigator of this study
Professor of Biostatistics
co-Director of the Harvard Data Science Initiative
Harvard T.H. Chan School of Public Health
Boston, MA

MedicalResearch.com: What is the background for this study? What are the main findings?

Response: The Clean Air Act requires Environmental Protection Agency to set National Ambient Air Quality Standard (NAAQS). Currently the annual NAAQS for PM2.5 is 12 microgram per cubic meter; and there is no annual or seasonal ozone standard. However, is current air quality standard stringent enough to protect human health? This is our main motivation.

We conducted the largest attainable cohort study, including over 60 million Medicare participants, to investigate the association between long-term exposure to ozone/PM2.5 and all-cause mortality.

We found significant harmful effect of PM2.5 even below current NAAQS. Each 10 microgram per cubic meter increase in PM2.5 is associated with 13.6% (95% CI: 13.1%~14.1%) increase in all-cause mortality. For ozone, 10 ppb increase in ozone exposure is associated with 1.1% (95% CI: 1.0%~1.2%) increase in mortality. Also, there is no appreciable level below which mortality risk tapered off. In other words, there is no “safe” level for PM2.5 and ozone.

In other words, if we would reduce the annual average of PM2.5 by just 1 microgram per cubic meter nationwide, we should save 12,000 lives among elder Americans every year; 5 microgram — 63,817 lives every year. Similarly, if we would reduce the annual summer average of ozone by just 1 ppb nationwide, we would save 1,900 lives every year; 5 ppb — 9537 lives.

Besides, we found black people, males and people of low SES are more vulnerable to air pollution.

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Western US Smog Increasingly Due To Asian Emissions

MedicalResearch.com Interview with:

Dr. Meiyun Lin PhD Research Scholar NOAA and Princeton University’s Cooperative Institute for Climate Science

Dr. Meiyun Lin

Dr. Meiyun Lin PhD
Research  Scholar
NOAA and Princeton University’s Cooperative Institute for Climate Science

MedicalResearch.com: What is the background for this study? What are the main findings?

Response: Ground-level ozone, also known as smog, has climbed in the rural West over the past 25 years, even in such seemingly pristine places as Yellowstone National Park. We have found out why – and why cutting our own output of smog-forming chemicals such as nitrogen oxides by 50% hasn’t helped. This study found that increased pollution from Asia, which has tripled its nitrogen oxide emissions since 1990, contribute to the persistence of smog in the West.

While ozone in the eastern U.S. has decreased overall, the levels can spike during heat waves, characterized by large-scale air stagnation, warm temperatures, and plentiful radiation needed for ozone formation locally. As heat waves appears to be on the rise due to global climate change, progress in reducing smog in the eastern US is likely to be slower in the coming decades.

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Air Pollution Linked To Millions of Preterm Births

MedicalResearch.com Interview with:

Chris Malley PhD The Stockholm Environment Institute University of York

Dr. Chris Malley

Chris Malley PhD
The Stockholm Environment Institute
University of York

MedicalResearch.com: What is the background for this study?

Response: When a baby is born preterm (at less than 37 weeks of gestation, an indicator of premature birth), there is an increased risk of infant death, or long-term physical and neurological disabilities. For example, 965,000 infant deaths in 2013 (35% of all neonatal deaths) have been estimated to be due to preterm birth complications. In 2010, an estimated 14.9 million births were preterm – about 4–5% of the total in some European countries, but up to 15–18% in some African and South Asian countries. The human and economic costs are enormous.

There are many risk factors for preterm birth – from the mother’s age, to illness, to poverty and other social factors. Recent research has suggested that exposure to air pollution could also be a risk factor. Our study quantifies for the first time the global impact of pregnant women’s exposure to outdoor fine particulate matter (PM2.5) by combining data about air pollution in different countries with knowledge about how exposure to different levels of air pollution is associated with preterm birth rates.

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Living Near Major Roads Associated With Increased Dementia Risk

MedicalResearch.com Interview with:

Hong Chen, PhD Scientist, Environmental Health Assessment Public Health Ontario | Santé publique Ontario Assistant Professor, Dalla Lana School of Public Health, University of Toronto Adjunct Scientist, Institute for Clinical Evaluative Sciences (ICES) Toronto, ON

Dr. Hong Chen

Hong Chen, PhD
Scientist, Environmental Health Assessment
Public Health Ontario | Santé publique Ontario
Assistant Professor, Dalla Lana School of Public Health
University of Toronto
Adjunct Scientist, Institute for Clinical Evaluative Sciences
Toronto, ON

MedicalResearch.com: What is the background for this study?

Response: Over the past several decades, there is unequivocal evidence that living close to major roadways may lead to various adverse health outcomes, such as cardio-respiratory related mortality and mortality. In the past decade, concern is growing that exposures associated with traffic such as air pollution and noise may also have an adverse impact on brain health. Several experimental studies show that air pollutants and diesel exhaust induce oxidative stress and neuroinflammation, activate microglia (which act as the first and main form of immune defense in the central nervous system), and stimulate neural antibodies. There are also a small number of epidemiological studies linking traffic-related noise and air pollution to cognitive decline and increased incidence of Parkinson’s disease and Alzheimer’s disease.

Studies also showed that living near roads was associated with reduced white matter hyperintensity volume and cognition, but its effect on the incidence of dementia, Parkinson’s disease, and multiple sclerosis is unknown. Given hundreds of millions of people worldwide live close to major roads, we conducted this population-based cohort study to investigate the association between residential proximity to major roadways and the incidence of these three neurological diseases in Ontario, Canada.

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Air Pollution May Shorten Lung Cancer Survival

Sandrah P. Eckel PhD Assistant Professor of Preventive Medicine USC Division of Biostatistics

Dr. Sandrah Eckel

MedicalResearch.com Interview with:
Sandrah P. Eckel PhD
Assistant Professor of Preventive Medicine
USC Division of Biostatistics

MedicalResearch.com: What is the background for this study? What are the main findings?

Response: Lung cancer is the most common cancer and it is responsible for 1 in 5 cancer deaths. There is a growing body of evidence that ambient air pollution exposures are linked to lung cancer incidence and mortality, but the effect on survival of exposures after diagnosis are unclear. The International Agency for Research on Cancer recently classified ambient air pollution as carcinogenic. We reasoned that if air pollution drives lung cancer development, it could impact lung cancer progression—and shorten survival—through the same biological pathways.

We used 20 years of data on more than 300,000 newly diagnosed lung cancer cases from the California Cancer Registry and calculated average air pollution exposures at each patient’s residence from the date of diagnosis through the end of follow-up. We found that patients living in areas with higher pollution levels had shorter survival, particularly for patients who were diagnosed at an early stage and for those diagnosed at an early stage with adenocarcinoma histology. Interestingly, adenocarcinoma is the most common histological subtype of lung cancer in non-smokers.

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Air Pollutants Linked To Risk of Myocardial Infarction

MedicalResearch.com Interview with:

Marko Mornar Jelavic, MD, PhD Department for Internal Medicine and Dialysis Health Center Zagreb Zagreb, Croatia

Dr. Marko Mornar Jelavic

Marko Mornar Jelavic, MD, PhD
Department for Internal Medicine and Dialysis
Health Center Zagreb
Zagreb, Croatia

MedicalResearch.com: What is the background for this study?

Response: Zagreb is the capital and the largest city of the Republic of Croatia which is placed in South-Eastern Europe. The wider Zagreb metropolitan area has the total population of up to 1.2 million (20% of the total Croatia’s population). The climate of Zagreb is classified as a humid continental. The average daily mean temperature in winter is around +1 °C (from December to February) and the average temperature in summer is 22.0 °C.

For the first time, we wanted to investigate whether particles of dimensions ≤10 micrometers (PM10) nitrogen dioxide (NO2) and ozone (O3), as well as certain meteorological conditions (air temperature, humidity and pressure) have any impact on appearance of myocardial infarction (MI) in the region with a humid continental climate.
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Air Pollution Linked to Increase in Hypertension Risk

MedicalResearch.com Interview with:
Tao Liu Ph.D
Guangdong Provincial Institute of Public Health
Guangdong Provincial Center for Disease Control and Prevention

MedicalResearch.com: What is the background for this study? What are the main findings?

Response: Hypertension is the most important cause of disability and the leading risk factor for death globally and causes approximately 16.5% of all deaths. Since the 1990s, many epidemiological studies have investigated the associations between air pollution exposure and hypertension, the two most common public health concerns. However, their results remain controversial. Some studies found an association between them, while other studies sowed either no association or an association only for selected pollutants. In order to quantitatively synthesize and interpret these inconsistent and controversial results, here we used a new analysis method (Meta-analysis) to combine results from different previous studies to estimate the overall effect of every air pollutant on hypertension. This is the first study to simultaneously estimate the effects of short-term and long-term exposure to air pollutants on hypertension by meta-analysis. These results could provide more explicit information for policy decisions and clinical use.

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Harmful Effects of Air Pollution Can Last Decades

MedicalResearch.com Interview with:

Dr Rebecca Ghosh, Research Associate Small Area Health Statistics Unit (SAHSU) MRC-PHE Centre for Environment and Health Imperial College London St Mary's Campus, Norfolk Place, Londo

Dr. Rebecca Ghosh

Dr Rebecca Ghosh, Research Associate 
Small Area Health Statistics Unit (SAHSU)
MRC-PHE Centre for Environment and Health
Imperial College London
St Mary’s Campus, Norfolk Place, London 

Medical Research: What is the background for this study? What are the main findings?
Dr. Ghosh: Since the 1950s a lot of evidence has accumulated that high levels of air pollution cause harmful effects on health.  However there is limited evidence on the very long term (>25 years) effects of air pollution.  Our study is one of the longest running to date looking at air pollution and mortality, following 368,000 people in England and Wales for 38 years.  We estimated air pollution exposures throughout England & Wales for 1971, 1981, 1991 and 2001 using data from historic air pollution monitoring networks, the first time this has been done.

We found that air pollution exposure in 1971 was still associated with a small increased risk of death in 2002-9, over 30 years later, suggesting that harmful effects of air pollution are extremely long-lasting.  However, risks from an individual’s past exposures waned over time and their more recent exposures gave the highest mortality risks.

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Indoor Air Purifiers Reduce Cardiopulmonary Effects Of Severe Air Pollution

MedicalResearch.com Interview with:
Dr. Renjie Chen PhD and Dr. Haidong Kan, PhD
School of Public Health, Key Lab of Public Health Safety of the Ministry of Education, Fudan University, Shanghai, China

MedicalResearch: What is the background for this study? What are the main findings?

Response: Although several previous studies in developed countries with cleaner air have reported health benefits due to air filtration, no such interventional studies were conducted in a developing country with much severer air pollution problems. Our main findings suggested that even a short-term intervention (2 days) could significantly reduce indoor air pollution and improve cardiopulmonary health among healthy young adults. Continue reading

Increased Air Pollution Linked To More Strokes, Smaller Brain Volumes

Elissa Hope Wilker, Sc.D. Beth Israel Deaconess Medical Center Cardiovascular Epidemiology Research Harvard Medical SchoolMedicalResearch.com Interview with:
Elissa Hope Wilker, Sc.D.
Beth Israel Deaconess Medical Center
Cardiovascular Epidemiology Research
Harvard Medical School

Medical Research: What is the background for this study? What are the main findings?

Dr. Wilke: Long-term exposure to ambient air pollution is associated with cerebrovascular disease and cognitive impairment, but the impact on structural changes in the brain is not well understood. We studied older adults living in the greater Boston area and throughout New England and New York and we looked at the air pollution levels and how far they lived from major roads. We then linked this information to findings from MRI studies of structural brain images. Although air pollution levels in this area are fairly low compared to levels observed in other parts of the world, we found that people who lived in areas with higher levels of air pollution had smaller brain volumes, and higher risk of silent strokes. The magnitude of association that we observed for a 2 µg/m3 increase in fine particulate matter (PM2.5) (a range commonly observed across urban areas) was approximately equivalent to one year of brain aging. The association with silent strokes is of concern, because these are associated with increased risk of overt strokes, walking problems, and depression.

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