Decades of research have shown that air pollutants such as ozone and particulate matter (PM) increase the amount and severity of lung and heart disease and other health problems. More studies are needed to further understand the role of poor air quality in causing adverse health effects and increased disease, particularly in vulnerable populations. Children, the elderly and people who live in areas with high levels of air pollution are particularly susceptible.
Results from these studies are used to support the nation’s air quality standards under the Clean Air Act and contribute to improvements in public health.
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Health effects of air pollutants on vulnerable populations
Research has shown that some people are more susceptible than others to air pollutants. These groups include children, pregnant women, older adults and people with pre-existing heart and lung conditions. People in low socioeconomic neighborhoods and communities may be more vulnerable to air pollution due to many factors. Proximity to industrial sources of air pollution, underlying health problems, poor nutrition, stress and other factors can contribute to increased health impacts in these communities.
There is a need for greater understanding of the factors that can influence whether a population or age group has an increased risk of health effects from air pollution. In addition, advances in analytical approaches used to study the health effects of air pollution will improve exposure estimates for healthy and exposed groups.
The research by EPA scientists and others informs the required reviews of the primary National Ambient Air Quality Standards (NAAQS), which are conducted with the development of Integrated Science Assessments (ISAs). These ISAs are mandated by Congress every five years to assess the current state of the science on criteria air pollutants and determine whether the standards provide adequate protection of public health.
The research is focused on addressing four areas:
- Identifying and characterizing whether there are important reproductive factors and critical developmental stages that are affected by exposure to air pollution;
- Determining the Role of Acute and Chronic Sociodemographic Factors in Air Pollution Health Disparities;
- Understanding how diet alters responses to air pollution;
- Evaluation of long-term lifestyle and chronic disease effects on air pollution-induced respiratory and cardiovascular responses
An interdisciplinary team of investigators coordinates epidemiologic, human observational, and basic toxicology research to assess the effects of air pollution in at-risk populations and develop strategies to protect these populations, particularly those with preexisting disease. The results from these products will improve risk assessments by clarifying the role of modifying factors such as psychosocial stress (eg noise) and diet, and by determining the impact of individual susceptibility on the relationship between air pollution exposure and health.
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Long-term and short-term effects from exposure to air pollutants
People can experience exposure to different concentrations of air pollution. Poor air quality can affect individuals for a short period of time during the day or more often during a given day. Exposure to pollutants can also occur over several days, weeks, or months due to seasonal air pollution, such as increased ozone in the summer or particulate matter from wood stoves in the winter.
The health impact of air pollution exposure depends on the duration and concentrations as well as the health status of the affected populations. Studies are needed to increase knowledge of the duration of exposure and the possible cumulative increase in risk.
The research is focused on three main areas:
- Short-term peak exposures, such as wildfires, traffic-related sources, or other episodic events;
- Intermittent and cumulative exposures;
- Mechanisms underlying exposure risks
Researchers are evaluating the health responses of intermittent multi-day versus single-day air pollution exposure in controlled human exposure, animal and in vitro models, and associated cellular and molecular mechanisms. They use population-based models and electronic health records to assess the health effects of short- and long-term exposures and identify populations at greatest risk of health effects. The work improves our understanding of the possible cumulative effects of multiple short-term peak exposures and the relationship between these exposures and long-term exposures and risks.
Multipollutant exposures and changes in environmental conditions
EPA research provides information to understand how individuals may respond to two or more pollutants or mixtures and how environmental conditions may affect air quality. While risk estimates of exposure to individual criteria air pollutants such as particulate matter and ozone are well established, the acute and cumulative effects of combinations of pollutants are not well understood. In addition, research is needed to determine how changes in the environment affect both the formation of pollutants and subsequent response to exposures in healthy and susceptible individuals.
The research is focused on three specific questions:
- What is the role of temperature and photochemical aging on the health effects of mixtures of wildfire smoke and air pollution?
- What is the effect of changing environmental conditions (ie temperature and humidity) on responsiveness to air pollution?
- Does prior exposure to pollutants alter responsiveness to subsequent exposures?
The integrated, interdisciplinary research includes:
- Epidemiological analyzes of environmental influences on morbidity and mortality in populations,
- Simulations of changing environmental conditions in the formation of multiple pollutants in atmospheric chamber studies combined with clinical and toxicological assessments in healthy and exposed populations,
- Evaluation of pre-exposure as a modifying effect on subsequent exposures
The results reveal how changes in environmental conditions affect the formation of pollutants and the subsequent health impact in the population at risk. The research findings inform EPA’s Integrated Science Assessments for criteria air pollutants and assist in future regulatory decisions on National Ambient Air Quality Standards (NAAQS).
Harnessing Big Data for Health Science Innovations
EPA is at the forefront of health science, using electronic health records, new data systems, tissue-like advanced cellular models, molecular approaches, and animal models to evaluate the health effects of air pollution. Researchers are using these powerful new techniques to identify factors that may increase sensitivity and vulnerability to air pollution effects.
The research builds capacity for future risk assessment and regulatory analyzes that go beyond traditional lines of evidence to more clearly define populations and life stages at increased risk of health effects from air pollution.
To continue to protect public health from poor air quality, researchers must consider new epidemiologic, toxicological, and clinical approaches to understand the health risks of poor air quality and the biological mechanisms responsible for these risks. At the center of these new research approaches is an explosion of data availability and methodological approaches for handling large clinical and molecular data sets, also known as “big data”.
While data of increasing size, depth, and complexity has accelerated research for many industries and scientific fields, big data is sometimes less recognized for its impact on environmental health research. Increasingly, researchers are able to examine vulnerable populations with unprecedented precision and detail, while also evaluating hundreds of thousands of molecular biomarkers to understand biological mechanisms associated with exposure.
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Health Effects of Wildfire Smoke
Larger and more intense wildfires create the potential for greater smoke production and chronic exposures in the United States, especially in the West. Wildfires increase air pollution in the surrounding areas and can affect regional air quality.
The health effects of fire smoke can range from eye and respiratory irritation to more serious conditions, including reduced lung function, worsening of asthma and heart failure, and premature death. Children, pregnant women and the elderly are particularly vulnerable to the effects of smoke. Emissions from wildfires are known to cause increased visits to hospitals and clinics by those exposed to the smoke.
It is important to more fully understand the human health effects associated with short- and long-term exposures to smoke from wildfires as well as prescribed fires, collectively referred to as wildfires. EPA conducts research to advance understanding of the health effects of various types of fires as well as phases of combustion. Researchers want to know:
- What is the full extent of health effects from smoke exposure?
- Who is most at risk?
- Are there differences in health effects from different fuel types or combustion phases (burning versus flame)?
- What strategies and approaches are most effective in protecting public health?
- What are the environmental, social and economic consequences of wildfire emissions?
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Public health intervention and communication strategies
Many communities across the United States face challenges in advising residents how to best protect their health when exposed to elevated concentrations of air pollutants from motor vehicle and industrial emissions and other combustion sources, including wildfire smoke.
Researchers are studying intervention strategies to reduce the health impacts of air pollution exposure as well as ways to effectively communicate these health risks. To translate science for use in public health communication and community empowerment, EPA collaborates with other federal agencies, such as the Centers for Disease Control and Prevention (CDC) and the National Heart, Lung, and Blood Institute (NHLBI), and state and local agencies and tribes. The goals are to identify ways to lower air pollution exposure or mitigate the biological responses at the individual, community, or ecosystem level, and ultimately evaluate whether such interventions have benefits as measured by indicators of health, well-being, or the economy.
Studies evaluate the interactions between behavior and social and economic factors to more thoroughly understand how these factors may influence health and well-being outcomes, which can inform effective and consistent health risk messaging.
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Integrated Science Assessments for Air Pollutants
EPA set National Ambient Air Quality Standards (NAAQS) before six main criteria air pollutants—nitrogen oxides, sulfur oxides, particulates, carbon monoxide, ozone and lead – all of which have been shown to be harmful to public health and the environment.
Agency’s Integrated Science Assessments (ISAs) provide the scientific basis for the review of the NAAQS standards by providing the primary (human health-based) assessments and secondary (welfare-based, e.g., ecology, visibility, materials) assessments. The ISAs are assessments of the state of the science with respect to the criteria pollutants. They are performed as mandated under the Clean Air Act.
