Climate Change and Respiratory Health

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Climate Change and Respiratory Health

• John R. Balmes, MD
• UCSF and UC Berkeley

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Climate Change

• Source greenhouse gases from combustion of
  fossil fuels
• Effects on weather
• Heat waves
• Wildland fires
• Storms
• Increased growing season in much of Northern
  Hemisphere
• Increased air pollution (especially ozone)

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Health Effects of Climate Change

• Exacerbation of respiratory disease (e.g.,
  asthma)
• Increased cardiopulmonary mortality
• directly due to heat
• due to increased air pollution
• due to interaction of heat and air pollution
• Increased transmission of infectious diseases
• Malnutrition from crop failure
• Increased pollen season so increased respiratory
  allergic reactions (e.g., asthma)

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Air Pollution (Smog)
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Ozone Formation in the Atmosphere
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Climate Change and Air Pollution

• As atmospheric concentrations of greenhouse gases
  rise globally, temperatures on earth are
  increasing.
• Higher temperatures, strong sunlight and a stable
  air mass are ideal for formation of ground level
  ozone (O3).
• In much of the US, a warming of 4 degrees (F)
  could increase O3 concentrations by about 5 (US
  EPA).

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Climate Change and Air Pollution

• Hotter summer weather leads to increased
  emissions of O3 precursors, particulate matter
  and toxic air contaminants from increased energy
  production, fuel evaporation and other sources.
• During hot summer days, air conditioners are used
  more frequently, leading to increased demand for
  electric power production and associated
  increases in smog-forming pollutants, such as NOx
  and hydrocarbons.
• Increased mobile air conditioning usage also
  leads to higher pollution emissions.

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Ozone Increases with Higher Temperatures
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Climate Change and Air Pollution

• The heat waves in Europe in summer 2003 provide a
  case study of heat-related O3 impacts on public
  health.
• During the heat waves there were thousands of
  excess deaths that occurred above the average
  recorded for that time of year.
• Epidemiological studies of deaths during the heat
  waves suggest that a substantial portion of the
  mortality could be attributed to elevated O3 and
  particulate levels that occurred during the heat
  waves.
• 20-50 of the total excess deaths can be
  attributed to elevated O3 and particle levels.

(Filleul et al.Johnson et al.)
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Climate Change and Air Pollution

• Californians already experience the worst air
  quality in the nation, with more than 95 of
  Californians living in areas with unhealthy air,
  according to the California Air Resources Board
  (CARB).
• The number of unhealthy days for O3 pollution
  (based on Californias air quality standards) has
  been approximately one out of every three days
  for some areas of the state, such as the South
  Coast Air Basin and the San Joaquin Valley.

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Ozone Concentrations Across the U.S.
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MECHANISMS OF OZONE TOXICITY

• Direct oxidation
• Free radical formation
• Lipid peroxidation
• Oxidative stress
• Secondary inflammation/repair

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Ozone - Potential Public Health Impact

• The current EPA national ambient air quality
  standard (NAAQS) for O3 is 0.08 ppm over 8 hours.
• Over 50 of U.S. population resides in areas that
  are not in attainment with the current NAAQS.
• Much of California is not in attainment.

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Acute Effects of Ozone

• Respiratory symptoms
• Acute decreases in lung function
• Increased airway responsiveness
• Airway injury and inflammation
• Systemic oxidative stress
• Cytogenetic damage in both buccal cells and
  peripheral blood lymphocytes

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Effects of Ambient Levels of Ozone on Lung
Function
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Chronic Exposure to Ozone

• Decreased lung function reflective of small
  airway remodeling found in
• UC Berkeley freshmen in association with
  lifetime exposure to O3 (Kunzli et al. Tager et
  al.).
• Decreased growth of lung function related to O3
  found in schoolchildren in Mexico City
  (Rojas-Martinez et al.).
• Abnormal development of airways in Rhesus monkeys
  exposed from birth. (Schelegle et al.)

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Asthma
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Ozone and Asthma

• Asthma is characterized by airway inflammation
  and airway hyperresponsiveness.
• O3 induces airway inflammation and airway
  hyperresponsiveness.
• Thus, people with asthma are considered to have
  increased susceptibility to O3.

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Ozone and Asthma

• EPIDEMIOLOGICAL STUDIES
• Multiple studies have shown increased ER visits
  and hospitalizations for asthma in association
  with high O3 levels.
• Panel studies of subjects with asthma have shown
  increased symptoms and medication use and
  decreased lung function in association with O3
  exposure.

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Epidemiological Studies of Ozone Effect on
Respiratory Diseases
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Ozone and Asthma

• Decreased asthma ER visits and hospital
  admissions for asthma in Atlanta during 1996
  Summer Olympics
• a) 20-40 decrease in asthma care
• b) peak O3 decreased from 81 to 59 ppb
• c) peak traffic counts decreased 23
• d) peak O3 correlated with peak traffic

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Ozone and Asthma
ER visits, hospital admits, urgent care visits
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Ozone and Asthma

• EVIDENCE FOR ASTHMA CAUSATION
• AHSMOG Study new-onset asthma in men associated
  with O3 exposure
• So. Calif. Childrens Health Study risk for
  new-onset asthma higher in children who played 3
  or more sports and lived in a high-O3 community

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Ozone Mortality Effect

• Two recent studies were published showing an
  effect of ambient ozone on daily mortality as has
  been seen with particulate matter (PM).
• A US study involving 95 metropolitan areas showed
  a 0.5 increase in mortality with a 10 ppb
  increase in ozone concentration.
• A European study of 23 cities showed a 0.33
  increase in mortality with a 10 mg/m3 increase in
  ozone concentration.

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Doseresponse of ozone 1 hour concentrations and
daily number of deaths during the summer season.
Gryparis et al. AJRCCM 20041701080-1087
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Public Health Policy Implications

• The current NAAQS for O3 is 0.08 ppm over 8
  hours.
• EPA studies have shown decreases in lung function
  and airway inflammatory changes in in healthy
  subjects exposed to 0.08 ppm over 6.5 hours with
  intermittent exercise.
• Multiple epidemiological studies show O3-related
  hospital admissions at levels lower than 0.08
  ppm.
• The EPA is currently considering a stricter O3
  standard.
• The California standard is 0.70 ppm.

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Burden of Disease in California due to Air
Pollution

• The current annual health impacts of exceeding
  state health-based standards for O3 and
  particulate matter
• 6,500 premature deaths
• 4,000 hospital admissions for respiratory disease
• 3,000 hospital admissions for cardiovascular
  disease
• 350,000 asthma attacks
• 2,000 asthma related emergency room visits
• elevated school absences due to respiratory
  conditions
• reduced lung function growth rate

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Climate Change, Air Pollution and Burden of
Disease

• Increased temperature will increase O3 and other
  pollutants which will increase the burden of
  disease.
• Sensitive groups, including the elderly, people
  with heart or lung disease, children and infants
  are the most vulnerable to the harmful effects of
  air pollution.
• Low-income communities are also especially
  vulnerable to air quality health impacts due to
  the multiple pollution sources located in these
  communities and often limited access to health
  care.

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Ozone and Temperature Interaction
Relative Risk of Respiratory Death per 10 ppb
increase in O3 concentration
Temperature
(Jerrett et al., in press)
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Climate Change and Allergy

• Increased pollen season will lead to increased
  respiratory allergic reactions in sensitized
  individuals
• Plant habitat changes will lead to exposure of
  previously unexposed populations so some
  individuals will become newly sensitized.

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Schematic summary of the impacts of climate
change on allergenic plants and pollens.
(Beggs)
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Percentage change in ragweed pollen quantities
produced under different concentrations of
atmospheric CO2.
(Beggs et al.)
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Peak date of airborne birch pollen
concentrations in Denmark, 19781999
(Gilmour)
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Ozone Exacerbates Allergic Asthma
Comparison of individual allergen challenge
PC15 results (n14) after exposure to filtered
air or 0.2 ppm ozone for 1 h with exercise
(Chen et al.)
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Climate Change
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Health Benefits from Greenhouse Gas Mitigation
Strategies
(Patz et al,)
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World Motor Vehicle Population Trends
(Walsh)
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Change in Greenhouse Gas Emissions by Sector
(Walsh)
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Summary

• Increased temperature leads to increased ozone
  formation
• Increased ozone will cause increased burden of
  disease
• Temperature and ozone interact to increase
  mortality
• Climate change will cause increased exposure to
  allergen and thus increased allergic disease
• Allergen and ozone interact to exacerbate asthma