What are the health effects of breathing ozone?

1. What are the health effects of breathing ozone? Feroza Daroowalla, MD, MPH Division of Pulmonary Medicine Stony Brook University These slides were derived from the EPA website

2. What is ozone? • Ozone is a highly reactive gas molecule made up of three oxygen atoms • Ozone occurs naturally in the stratosphere (upper atmosphere) • In the lower atmosphere, ozone is formed primarily from photochemical reactions of man-made air pollutants =Tropospheric ozone or "ambient" or "ground-level" ozone

3. What is asthma? • Asthma is a chronic inflammatory disease of the airways that causes recurrent episodes of wheezing, breathlessness, chest tightness, and cough

4. Background Information • The prevalence of asthma has doubled in the U.S. in the last 20 years • More than 20 million Americans report having asthma • Rates are higher among children under 17, minorities, and inner-city populations • 10 million patient visits and more than 470,000 hospital admissions annually

5. Effects on human health • Breathing in ground level ozone damages the respiratory tract • Respiratory symptoms • Decreases in lung function • Inflammation of airways

6. What are the symptoms of ozone exposure • Coughing • Throat irritation • Pain, burning, or discomfort in the chest when taking a deep breath • Chest tightness, wheezing, or shortness of breath

7. What effects does ozone have at the cellular level? • Ozone does not get scrubbed out in the upper respiratory tract • Reaches the lower respiratory tract and dissolves in the thin layer of fluid lining the airways of the lung • Then ozone reacts rapidly with a number of biomolecules • This results in free radicals and other oxidant species • These react with epithelial cells, immune cells, and with nerve receptors in the airway wall

8. How does ozone act in the lung • Injury and inflammatory response result in : • An increase in small airway obstruction • A decrease in the barrier function of the airway epithelium • An increase in airway reactivity • After a period of weeks following a single exposure, the airway appears to return to the pre-exposure state

9. Does response vary among individuals? • There is large variation in the response among individuals • Some people may experience no symptoms or lung function changes while the most responsive individual may experience a 50% drop in lung function and have severe coughing, shortness of breath, or pain on deep inspiration.

10. Which populations are susceptible to ozone damage • One factor that explains variability is age, • young adults (teens to thirties) are more responsive than older adults (fifties to eighties) • data do not suggest that children are more responsive than young adults • Children may have more response if they are more exposed (spend more time outside) • People with asthma are the most responsive group

12. How does ozone affect people with asthma? • Increased frequency of asthma attacks • Increased use of health care services • A worsening of underlying asthma status, increasing the likelihood of an asthma attack or requiring more treatment • Studies indicate a relationship between ambient ozone concentration and medication use among children and ER visits and hospital admissions for asthma

13. How quickly do ozone-induced respiratory symptoms resolve in individuals without asthma? • They should begin to improve immediately upon cessation or reduction of exposure and should have disappeared completely within 24 to 48 hours after the exposure ends

14. What are the effects of recurrent or long-term exposure to ozone? • One of the major unanswered questions • whether repeated episodes of damage and repair due to years of short-term ozone exposures result in health effects • Some early evidence that long-term ozone exposure may result in new asthma • suggest that young children may be especially susceptible to effects of ozone on lung development • Prudent to avoid repeated short-term exposures, particularly in young children, until more is known

15. How much is too much • More potential for effect with longer time active outdoors and with more strenuous activity • Human exposure studies indicate that: • levels above 0.12 ppm, heavy outdoor exertion for 1 to 3 hours can increase risk • levels between 0.08 and 0.12 ppm, moderate outdoor exertion for 4 to 8 hours can increase risk • Moderate exertion = climbing stairs, tennis or baseball, simple garden or construction work, and light jogging, cycling • Heavy exertion = playing basketball or soccer, chopping wood, heavy manual labor, and vigorous running, cycling

16. What is the Air Quality Index? • The Air Quality Index tells the public how clean or polluted the air is • The AQI uses a scale from 0 to 500 • The higher the AQI value, the greater the level of pollution and the greater the health concern • AQI values below 100 are generally considered to be satisfactory • The AQI is divided into six categories that correspond to different levels of health concern.

17. When AQI values are above 100, air quality is considered to be unhealthy, at first for members of susceptible populations, then for everyone as AQI values get higher

18. How can you reduce exposure to ozone? • What is moderate exertion for one person may be heavy exertion for another • Cutting back on the level and duration of exertion when ozone levels are high will help • The times of poorest air quality are typically in the afternoon and early evening for most locations

19. Information • Information about the health effects of ozone may be found on the AIRNow Web site in the Publications section (http://airnow.gov/index.cfm?action=static.publications) and the Your Health section (http://airnow.gov/index.cfm?action=static.health). (http://www.epa.gov/ncepihom/)