Frequent Questions about Particle Pollution
This section provides information for counseling patients about particle pollution as it relates to cardiovascular disease, stroke, and respiratory symptoms.
- Is ambient particle pollution exposure a risk factor for triggering myocardial infarction, arrhythmia, and stroke?
- Should I recommend that my older patients reduce their exposure to particle pollution on days when air quality is unhealthy?
- Should I advise my patients with respiratory disease, cardiovascular disease, and diabetes to limit their exposure to particle pollution?
- How can an individual reduce his/her exposure to particle pollution?
- How can a patient find out what times of day are typically more polluted for a given location?
- How can a patient find out when air quality is predicted to be unhealthy?
- Should a patient be advised to limit exercise when air quality is unhealthy?
- Are there any clinical effects of chronic exposure to particle pollution in healthy individuals?
- What symptoms can acute particle pollution exposure produce?
- How quickly should particle pollution-induced respiratory effects resolve after particle pollution exposure?
- Where can my patients find information about the health effects of particle pollution exposure?
- What are the most important defense mechanisms activated by inhalation of particle pollution?
- What are the potential adverse impacts of acute exposure(s) to ambient particle pollution?
- What are the potential adverse impacts of chronic exposure to ambient particle pollution?
- What are the most clinically important cardiovascular health effects due to acute and chronic exposure to particle pollution?
- What are the potential mechanisms accounting for cardiovascular effects due to acute and chronic exposure to particle pollution?
- What can my cardiovascular patients do to avoid exposure?
- Does exposure to particle air pollution worsen exercise-induced ischemia in people with ischemic heart disease?
- Does chronic exposure to air particle pollution accelerate atherosclerosis?
1. Is ambient particle pollution exposure a risk factor for triggering myocardial infarction, arrhythmia, and stroke?
Yes. Epidemiological studies provide evidence of a consistent association between the level of particle pollution exposure and cardiovascular death, cardiovascular events such as myocardial infarction, and hospitalization for cardiovascular disease (arrhythmia and congestive heart failure) and ischemic stroke.
2. Should I recommend that my older patients reduce their exposure to particle pollution on days when air quality is unhealthy?
Yes. Older adultsolder adults In many studies, older adults are defined as ages 65 years and older due to age definitions provided in health datasets such as the Medicare database. In terms of increased risk from air pollution, there is not a specific age at which someone is considered “older” because people age at different rates. As a person ages, there is greater susceptibility to environmental hazards due to a number of factors, including higher prevalence of pre-existing respiratory and cardiovascular disease, as well as the gradual decline in physiological defenses that occur as part of the aging process. , particularly those with prevalent cardiovascular and respiratory disease, are at higher risk from the adverse effects of particle pollution exposure. It seems prudent to advise these individuals to avoid exposure when possible.
3. Should I advise my patients with respiratory disease, cardiovascular disease, and diabetes to limit their exposure to particle pollution?
Yes. Similar to older adults, these clinical sub-populations appear to be at greater risk from particle pollution exposure and should generally be advised to reduce unhealthy levels of exposure when possible.
4. How can an individual reduce his/her exposure to particle pollution?
Exposure can be decreased by limiting the time spent outdoors or reducing the duration or intensity of outdoor activity during the times of day that particle pollution and gaseous pollutants (such as ozone ozone Ground level ozone is not emitted directly into the air, but is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC). This happens when pollutants emitted by cars, power plants, industrial boilers, refineries, chemical plants, and other sources chemically react in the presence of sunlight. Ozone at ground level is a harmful air pollutant, because of its effects on people and the environment, and it is the main ingredient in “smog.") tend to be highest in your area. These times of poorest air quality are typically in the afternoon and early evening for most locations, but this can vary by location.
5. How can a patient find out what times of day are typically more polluted for a given location?
On the AirNow website there is a map of the United States. Selecting a state will lead to a table with links for the state or local air quality agency that issues air quality forecasts. These agencies will be able to provide information about local particle pollution patterns.
- Air quality forecasts can be found with weather forecasts, either in local newspapers or on TV or the radio.
- Forecasts may also be found on national news media such as The Weather Channel and in USA Today.
- Forecasts are available on the AirNow website.
- Your patient can download the free AirNow Mobile App which provides location-specific air quality forecasts.
- Your patient can sign up to receive forecasts via e-mails through EPA's EnviroFlash program.
7. Should a patient be advised to limit exercise when air quality is unhealthy?
Yes, when air quality is unhealthy, your patient should limit outdoor exercise and consider exercising at an indoor location that has air conditioning (e.g., a mall, health club, or home). Exercise increases heart rate, respiratory rate and minute ventilation. Consequently, exercise increases exposure and, subsequently, dose rate to particle pollution. One should limit exercising near busy roads where particle pollution concentrations are significantly increased due to the accumulation of combustion products from automobiles, trucks, and road dust. Yet, regular exercise decreases cardiovascular risk and should be encouraged for everyone in the population and as appropriate for those at risk for cardiovascular disease.
8. Are there any clinical effects of chronic exposure to particle pollution in healthy individuals?
Epidemiological data support that chronic exposure of a population to particle pollution over many years decreases life expectancy and increases the risk of death from heart disease. Additionally, there is evidence from epidemiologic studies indicating that long-term exposure to particle pollution may also lead to lung cancer. Conversely, recent studies in areas where air quality has improved show that reductions of ambient particle pollution concentrations are associated with increased longevity and improved lung function in children.
9. What symptoms can acute particle pollution exposure produce?
Acute exposures to particle pollution (hours or days) can aggravate respiratory disease, causing asthma attacks and acute bronchitis, and may also increase susceptibility to respiratory infections. In people with cardiovascular disease, acute exposures are linked to heart attacks, ischemic strokes, exacerbations of heart failure, and some types of arrhythmia. Additionally, there is evidence that short-term exposures can lead to premature death in individuals with preexisting heart and lung disease. Healthy children and adults have not been reported to suffer serious effects from acute exposures, although they may experience temporary minor irritation (e.g., coughing, wheezing, and shortness of breath) when particle pollution levels are elevated.
10. How quickly should particle pollution-induced respiratory effects resolve after particle pollution exposure?
For respiratory effects, inhaled particle pollution increases the oxidative burden on the cells leading to airway hyper-reactivity and airway inflammation. Depending on the intensity of exposure, the recovery and spontaneous healing can take days after the exposure ends.
- AirNow website
- AirNow Publications section
- AirNow Your Health section
- Copies of publications may be ordered free of charge from the National Service Center for Environmental Publications (NSCEP).
- Publication requests can also be mailed, called, or faxed directly to:
U.S. Environmental Protection Agency
National Center for Environmental Publications (NSCEP)
P.O. Box 42419
Cincinnati, OH 42419
(513) 489-8695 (fax)
Please use the EPA Document Number, which is usually in bold or highlighted, when ordering from NSCEP.
- The mucociliary escalator moves trapped particles in the mucus towards the airway opening, where they are either swallowed or coughed out.
- Phagocytosis of smaller particles by phagocytes (e.g., white blood cells, macrophages).
- The health response to inhaled particle pollution is highly variable. Particle pollution concentration, exposure dose, and health of an exposed individual are the key determinants of response.
- Sensitive groups (children, older adults, people with heart and lung disease, and people with diabetes) may experience prolonged duration of symptoms, in part due to increased retention of particles.
- Individuals with respiratory disease such as asthma, allergies, chronic bronchitis and COPD may experience exacerbation and aggravation of symptoms such as coughing, sneezing, tightness of chest, and dyspnea.
- Exposure to high levels of particle pollution may lead to airway irritation, increased airway reactivity, and inflammation. This may require hospitalization of individuals with moderate to severe pulmonary disease.
- Exposure to high particle pollution levels may lead to increased absenteeism in school and the workplace.
- Individuals may increase their use of medication, particularly rescue medication with high levels of particle pollution exposure.
- Additionally, there is evidence that short-term exposures can lead to premature death in individuals with preexisting heart and lung disease.
- Decrements in lung function growth in children.
- Increased risk of developing respiratory symptoms and asthma.
- Acceleration of the development of atherosclerosis.
- Increased morbidity and mortality.
15. What are the most clinically important cardiovascular health effects due to acute and chronic exposure to particle pollution?
Acute exposures occurring over hours to days can lead to a range of cardiovascular effects including an increase in cardiovascular morbidity and mortality, as well as an increase in hospitalizations for acute coronary syndrome (including myocardial infarction and unstable angina), arrhythmia, exacerbation of chronic heart failure, and stroke. Epidemiological data provide compelling evidence that inhalation of particle pollution increases the risk of acute coronary syndrome, some types of arrhythmia, hospitalizations for heart failure, and stroke. Chronic exposures occurring over years can also result in cardiovascular effects including increased risk of cardiovascular mortality and the progression of atherosclerosis. Chronic exposures appear to increase the risk of death due to cardiovascular disease and possibly lung cancer.
16. What are the potential mechanisms accounting for cardiovascular effects due to acute and chronic exposure to particle pollution?
The mechanisms by which exposure to fine particle pollution can affect the cardiovascular system are under continuous examination. Exposure to inhaled fine particles appears to affect cardiovascular health through three primary pathways:
- Systemic inflammation.
- Translocation into the blood.
- Direct and indirect effects on the autonomic nervous system.
Oxidative stress is an underlying effect due to particle exposure that has been shown to impact endothelial function, pro-thrombotic processes, cardiac electrophysiology, and lipid metabolism.
17. What can my cardiovascular patients do to avoid exposure?
Patients with established cardiovascular disease, particularly those with chronic heart failure, appear to be at higher risk from particle pollution. Accordingly, patients with established heart and vascular disease—as well as those at high risk for cardiovascular disease, for example those with diabetes—should be counseled to limit their exposures to particle pollution. Patients should be educated about the AQIAir Quality Index (AQI) A nationally uniform index for reporting and forecasting daily air quality. It is used to report on the four most common ambient air pollutants that are regulated under the Clean Air Act: ground-level ozone, particle pollution (PM10 and PM2.5), carbon monoxide (CO), and sulfur dioxide (SO2). The AQI focuses on health effects that may be experienced within a few hours or days after breathing polluted air. and how to locate this information on the AirNow website, or in other available local media, or encouraged to sign up for EPA's EnviroFlash emails or download the AirNow Mobile App (both the email and App information are on the AirNow website). They should avoid exercising outdoors near busy roads or outdoors when the AQI indicates that the air is unhealthy for sensitive groups sensitive groups (also called at-risk populations) A term used for a category of persons at increased risk of experiencing adverse health effects related to air pollution exposures. These groups can be at increased risk due to intrinsic (biological factors), extrinsic (external, non-biological factors), higher exposure, and/or increased dose at a given concentration. The severity of the health effects that these groups experience may be much greater than in the general population..
The likelihood of being affected by particle pollution increases the longer one is active outdoors and the more strenuous the activity. If your patient’s activity requires heavy exertion, your patient can reduce the time spent on this activity or substitute another activity that requires more moderate exertion (e.g., go for a walk rather than a jog). In addition, patients can plan outdoor activities when particle pollution and other air pollutant levels are lower, usually in the morning or evening. Keeping windows and doors shut with air conditioning can reduce indoor exposure when outdoor levels of particle pollution are high. Indoor HEPA air filters have also been shown to be effective in lowering indoor concentrations of particle pollution.
18. Does exposure to particle pollution worsen exercise-induced ischemia in people with ischemic heart disease?
Two repeated measure studies (Pekkanen et al., 2002; Chuang et al., 2008) and a diesel particle exposure study (Mills et al., 2007) have demonstrated that exposure to particle pollution worsens electrocardiographic ST segment depression in people with ischemic heart disease. While these data suggest that exposure to particle pollution worsens ischemia, controversy still exists as to whether deeper ST depression relates to greater ischemia or a non-ischemic cause of ST depression induced by particle pollution. Nevertheless, when such findings are taken in the context of the increased risk of cardiovascular events, one must consider that the measured ST segment depression does in fact signify a greater degree of ischemia for the same workload in the absence of air particle exposure. Accordingly, people with established coronary artery disease are at higher risk from particle pollution and should be advised to consult the AQI and avoid exposure when possible.
19. Does chronic exposure to particle pollution accelerate atherosclerosis?
Epidemiological data and animal exposure data suggest that chronic exposure to particle pollution accelerates atherosclerosis. The Multi-Ethnic Study of Atherosclerosis (MESA) Air Pollution sub-study, funded by EPA and the National Institutes of Health, showed that long-term exposure to fine particle pollution (PM2.5) and NO2 was associated with an increase in coronary artery calcium. Two other epidemiology studies showed a positive association between long-term exposure to fine particles and the severity of coronary artery disease.