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Review Questions

An answer key appears at the end of the review questions.

  1. Harmful ambient ozone levels typically occur in the summertime, but they can occur throughout the year in some southern and mountain locations.
          A. True
          B. False

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  1. Only individuals who exercise heavily outdoors are affected by ozone.
          A. True
          B. False

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  1. Only individuals living near urban areas are at risk of significant ozone exposure.
          A. True
          B. False

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  1. In the general population, short-term ozone exposure is associated with
          A. An increase in daily mortality
          B. Lung function changes
          C. Respiratory inflammation
          D. Respiratory symptoms
          E. B, C, and D
          F. All of the above

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  1. Individuals with which of the following conditions are more susceptible to the effects of ozone?
          A. Allergic rhinitis
          B. Asthma
          C. Angina
          D. Congestive heart failure

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  1. The mechanisms that might contribute to ozone's ability to worsen existing asthma include:
          A. Increased nonspecific airway reactivity
          B. Increased respiratory inflammation
          C. Increased responsiveness to inhaled allergen
          D. A and C only
          E. A, B, and C

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  1. Ozone health effects can be reduced by:
          A. Reducing activity level during high ozone periods
          B. Drinking plenty of fluids
          C. Spending more time indoors during high ozone periods
          D. A and C only
          E. A, B, and C

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  1. Ozone is primarily scrubbed from inhaled air in the nose.
          A. True
          B. False

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  1. Common symptoms due to short-term ozone exposure include:
          A. Cough
          B. Pain on deep inspiration
          C. Eye irritation
          D. Shortness of breath
          E. A, B, and D
          F. A, C, and D

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  1. Hospital admissions for respiratory disease tend to be higher than normal following days on which ozone concentrations are high.
          A. True
          B. False

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  1. Recent ozone exposure can be assessed by measuring ozone levels in the blood.
          A. True
          B. False

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  1. Long-term exposure to ozone is known to be relatively harmless.
          A. True
          B. False

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  1. Short-term ozone exposure has been associated with increased medication usage among people with asthma.
          A. True
          B. False

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  1. Indoor concentrations of ozone are usually lower than outdoor concentrations.
          A. True
          B. False

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  1. There is a wide range in the sensitivity of otherwise healthy individuals to ozone.
          A. True
          B. False

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  1. Older adults have larger lung function and symptom responses to ozone exposure than do younger adults.
          A. True
          B. False

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  1. Ozone-induced respiratory symptoms are the result of stimulation of airway neural receptors by ozone or other reactive intermediates.
          A. True
          B. False

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  1. Ozone-induced respiratory symptoms in individuals without asthma may take 1 week to completely resolve.
          A. True
          B. False

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  1. The Air Quality Index (AQI) health and cautionary statements are pollutant-specific, and they suggest relatively simple measures people can take to reduce their risk from exposure to air pollution.
          A. True
          B. False

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  1. The AQI has sub-indices for the following pollutants:
          A. Ozone
          B. Particulate matter (PM2.5 and PM10)
          C. Carbon monoxide
          D. Sulfur dioxide
          E. Nitrogen dioxide
          F. All of the above

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Answer Key
Correct answers are highlighted in green.
  1. Harmful ambient ozone levels typically occur in the summertime, but they can occur throughout the year in some southern and mountain locations.

          A. True
          B. False

Within the last decade, high ozone concentrations have been observed under specific circumstances in cold months, where a few high elevation areas in the Western U.S. with high levels of local VOC and NOx emissions have formed ozone when snow is on the ground and temperatures are near or below freezing.  Ozone contributes to what we typically experience as "smog" or haze, which still occurs most frequently in the summertime, but can occur throughout the year in some southern and mountain regions.

  1. Only individuals who exercise heavily outdoors are affected by ozone.

          A. True
          B. False

Anyone who spends time outdoors when ozone levels are high may be affected, but people who exercise heavily, such as children, joggers and outdoor workers, may be at particular risk for experiencing ozone health effects. This is because the effects of ozone exposure relate directly to the inhaled dose, which depends, in part, on how hard an individual is breathing (minute ventilation). Ozone exposure also depends on the ambient ozone concentration and the duration of exposure.

  1. Only individuals living near urban areas are at risk of significant ozone exposure.

          A. True
          B. False

As a result of long-range transport of ozone or ozone precursors, ground-level ozone can occur many miles from emission sources and, therefore, can be higher in rural areas than in urban areas.

  1. 4. In the general population, short-term ozone exposure is associated with

          A. An increase in daily mortality
          B. Lung function changes
          C. Respiratory inflammation
          D. Respiratory symptoms
          E. B, C, and D
          F. All of the above

Ozone exposure has been experimentally determined to cause lung function changes, respiratory inflammation, and respiratory symptoms in all populations. Multiple epidemiological studies have observed an association between short-term ozone concentration and daily mortality rates. Although it may ultimately turn out that the individuals most at risk of dying have underlying disease, this has not been established at this time.

  1. Individuals with which of the following conditions are more susceptible to the effects of ozone?

          A. Allergic rhinitis
          B. Asthma
          C. Angina
          D. Congestive heart failure

Numerous studies have reported that elevated ozone levels are associated with aggravation of asthma, but ozone has not been shown to be associated with allergic rhinitis, angina, or congestive heart failure. Sensitive groups also include children; people with other lung diseases, such chronic bronchitis, and emphysema; older adults; and active people who work or exercise outdoors.

  1. The mechanisms that might contribute to ozone's ability to worsen existing asthma include:

          A. Increased nonspecific airway reactivity
          B. Increased respiratory inflammation
          C. Increased responsiveness to inhaled allergen
          D. A and C only
          E. A, B, and C

Exposure to ozone has been shown to cause each of these health endpoints, and each health endpoint contributes to aggravation of existing asthma.

  1. Ozone health effects can be reduced by:

          A. Reducing activity level during high ozone periods
          B. Drinking plenty of fluids
          C. Spending more time indoors during high ozone periods
          D. A and C only
          E. A, B, and C

Reducing outdoor activity level and staying indoors when ozone levels are high will reduce ozone exposure and reduce the amount of ozone penetrating deeply into the lungs. Drinking plenty of fluids has no effect on ozone exposure or ozone-related health effects.

  1. Ozone is primarily scrubbed from inhaled air in the nose.

          A. True
          B. False

Most ozone breathed penetrates into the lungs. Because ozone has limited solubility in water, the upper respiratory tract is not as effective in scrubbing ozone from inhaled air as it is for more water soluble pollutants such as sulfur dioxide (SO2) or chlorine gas (Cl2). Consequently, the majority of inhaled ozone reaches the lower respiratory tract and dissolves in the thin layer of epithelial lining fluid (ELF) throughout the conducting airways of the lung.

  1. Common symptoms due to short-term ozone exposure include:

          A. Cough
          B. Pain on deep inspiration
          C. Eye irritation
          D. Shortness of breath
          E. A, B, and D
          F. A, C, and D

Exposure to elevated ozone levels has been shown to cause cough, chest pain, and shortness of breath. The mechanisms that cause this are explained in the section "What are ozone's acute physiological and symptom effects?" Eye irritation is not caused by ozone but by peroxyacetyl nitrate (PAN), which is a different oxidant that often is formed in the ambient air when ozone levels are high.

  1. Hospital admissions for respiratory disease tend to be higher than normal following days on which ozone concentrations are high.

          A. True
          B. False

Epidemiologic studies have found associations between elevated ambient ozone levels and increased hospital admissions for respiratory disease about 24 hours later. This lag may be related to the delayed inflammatory response caused by exposure to ozone.

  1. Recent ozone exposure can be assessed by measuring ozone levels in the blood.

          A. True
          B. False

Ozone is a reactive gas that reacts with molecules in the epithelial lining fluid or the airway epithelium itself and, therefore, it does not enter the bloodstream through the lungs. Ozone has been measured in the blood but is present as a result of endogenous production.

  1. Long-term exposure to ozone is known to be relatively harmless.

          A. True
          B. False

Experimental animal studies have shown that long-term exposure to ozone can cause permanent changes in lung structure, described as scarring of lung tissue. There is concern that repeated episodes of inflammation may permanently alter lung structure and may lead to reduced quality of life in older individuals.

  1. Short-term ozone exposure has been associated with increased medication usage among people with asthma.

          A. True
          B. False

In epidemiologic studies, ozone exposure has been associated with aggravation and worsening of asthma, as evidenced by increased medication usage among individuals with asthma. Figure 11 summarizes some of these findings.

  1. Indoor concentrations of ozone are usually lower than outdoor concentrations.

          A. True
          B. False

Without sunlight, ozone does not form indoors, and ambient ozone that makes its way indoors tends to be destroyed by reacting with anything it comes in contact with (e.g., walls, furnishings). If windows are closed and air conditioning is used in the summer, indoor ozone levels can be as low as 10% of outdoor levels.

  1. There is a wide range in the sensitivity of otherwise healthy individuals to ozone.

          A. True
          B. False

Some healthy individuals, possibly as many as 5 % to 20 % of the population, have been shown to be very sensitive to low-level exposure to ozone, while others show little or no response to low-level ozone exposure.

  1. Older adults have larger lung function and symptom responses to ozone exposure than do younger adults.

          A. True
          B. False

Older adults (fifties to eighties) have been shown in clinical studies to be less responsive to ozone than younger adults (teens to thirties).

  1. Ozone-induced respiratory symptoms are the result of stimulation of airway neural receptors by ozone or other reactive intermediates.

          A. True
          B. False

Human and animal studies suggest that stimulation of airway neural receptors is the primary mechanism causing ozone-induced respiratory symptoms.

  1. Ozone-induced respiratory symptoms in individuals without asthma may take 1 week to completely resolve.

          A. True
          B. False

Typically ozone-induced respiratory symptoms in individuals without asthma will return to normal within 24 to 48 hours after ozone exposure ceases.

  1. The Air Quality Index (AQI) health and cautionary statements are pollutant-specific, and they suggest relatively simple measures people can take to reduce their risk from exposure to air pollution.

          A. True
          B. False

These cautionary statements and measures to reduce risk from air pollution exposure can be found in EPA's Air Quality Index brochure. For example, when the AQI Value for ozone is between 101 and 150, or Code Orange, air quality is considered "unhealthy for sensitive groups," and children, older adults, people who are active outside, and people with lung disease, such as asthma, are advised to reduce prolonged or heavy exertion outdoors.

  1. The AQI has sub-indices for the following pollutants:
          A. Ozone
          B. Particle pollution
          C. Carbon monoxide
          D. Sulfur dioxide
          E. Nitrogen dioxide
          F. All of the above

The only "criteria pollutant" for which there is no AQI sub-index is lead.

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