ARRA IMPACT REPORT:
Air Pollution Health Effects
Public Health Burden
Air Pollution contains harmful gases (e.g., ozone, oxides of sulfur, and nitrogen), small particles, and particulates both from natural (wild fires) and manufactured (car emissions, factories) sources. Exposure to air pollution remains a major public health concern. The health risks of air pollution include defective lung development and function and significant increases in cardiopulmonary morbidity and mortality. These risks are dependent on the quality and the amount of the air we breathe in a given time period, and our overall general health. Although air quality has improved in recent years, children and the elderly are especially vulnerable to the effects of air pollution.
The ARRA-funded grants utilized sophisticated cell and mouse models to examine the mechanisms by which particulate matter (PM) contributes to adverse health outcomes. Understanding these mechanisms will allow for the development of biomarkers of exposure and will assist in providing strong scientific bases for epidemiological studies and ultimately for regulatory agencies.
- Lung Surfacant Proteins and Asthma: Studies that focused on detailed characterization of surfactant proteins in the mouse lung indicated a role for surfactant protein D in ozone-induced exacerbations of asthma. These studies suggest surfactant protein Dis a potential target for therapeutic prevention and treatment of chronic airway inflammation.1
- Diesel Exhaust Particles: Investigators studying the effects of a specific type of PM [diesel exhaust particles (DEP)] on proteins that have the potential to regulate lung injury or respiratory dysfunction have identified transient receptor potential ankyrin-1 (TRPA1) as a specific target for electrophilic chemical components of DEP.2
Children and the elderly are both highly vulnerable to the negative health effects of air pollution. Children receive a larger dose of environmental toxicants than adults, and their organs and tissues are rapidly developing. Similarly, the underlying disease status and exposure scenarios for elderly adults increase their susceptibility to negative health impacts.
ARRA funds supported research in examining the health effects of air pollution on these sensitive populations, including impacts on airway diseases and inflammation, early markers of cardiovascular changes, and improved exposure assessment measures.
- Impact of Early Life Exposure to Outdoor Air Pollutants on Carotid Artery Thickening: The University of Southern California Center for Children’s Research conducted an ancillary study to determine if early life exposure to outdoor air pollutants promotes artery deposits that may lead to carotid artery thickening in 10-12 year olds. With ARRA funds, researchers were able to add repeated measures of Carotid Intima-Media Thickness test (CIMT) to objectively measure the extent of carotid atherosclerotic vascular disease in a subset of children enrolled in the California Children’s Health Study.3
- Air Pollutant-mediated Acute Cardiovascular Events: Researchers at University of California Irvine received ARRA funding to assess whether key genes of inflammatory and oxidative stress responses are differentially expressed in peripheral blood of elderly individuals with coronary artery disease (CAD) in relation to PM air pollution. They found positive associations of PM exposure with peripheral blood gene expression of genes in pathways representing inflammation, coagulation, and Nrf2-mediated oxidative stress response. These findings provide significant clues to the molecular mechanisms responsible for air pollutant-mediated acute cardiovascular events as well as demonstrate the feasibility of repeated measures of whole blood gene expression in humans as a potentially powerful new tool in population studies.4
Research Methods Development
Major research gaps in the epidemiology of air pollution include the need for improved methods to assess personal exposure to air pollution and the ability to tease apart the relative contribution of different components of air pollution mixtures to overall disease risk. ARRA funds supported research in addressing these two limitations.
- Particulate Matter Aerosols and Childhood Asthma: Researchers at the University of Medicine and Dentistry of New Jersey received supplemental ARRA-funds to accelerate the rate of recruitment of study subjects in an ongoing pilot study of indoor air pollution and childhood asthma using a Pre-Toddler Inhalable Particulate Environmental Robotic (PIPER) Sampler. As a result of the ARRA funding, additional personnel were engaged to assist with the field sampling of the homes and construct an additional PIPER. This new sampler can now be used in a larger study to validate preliminary findings, which suggest that PIPER may provide an alternative and more precise method for assessing young children’s exposures to a variety of particulate matter aerosols. 5
- Chemical Mixtures in Air Pollution: Researchers at Harvard University received ARRA funding to develop new statistical methods to estimate the adverse effects of exposure to chemical mixtures, with a specific focus on chemical components of PM air pollution. These new methods are now being applied to the largest databases available for estimating the toxicity of the PM mixture to obtain national and local estimates of health effects. It is anticipated that findings from these studies will significantly impact air pollution regulation in the US.6
Contributing NIH Institutes & Centers
- National Institute of Environmental Health Sciences (NIEHS)