Air Pollution: Exercise in the City

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Air Pollution Exercise in the City
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• From the standpoint of coaches and athletes,
  carbon monoxide is the most important of the
  primary pollutants. The principle source of
  carbon monoxide is automotive exhaust. Carbon
  monoxide exerts its effect by binding to and
  blocking the oxygen-binding sites on hemoglobin
  in the red blood cells (forming the molecule
  HbCO). Hemoglobin has an affinity for CO that is
  230 times greater than its affinity for oxygen
  This means that increased levels of carbon
  monoxide in the blood compromise both the
  transport of oxygen in the blood, and the
  extraction of oxygen to the tissuesThe immediate
  impact of this on exercise performance is that as
  the concentration of HbCO in the blood increases
  there is a decrement in maximum oxygen
  consumption(and a decrease) in maximal exercise
  time.
• Peter N. Frykman, 1988

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Pollution A Modern Environmental Stressor

• Nervous system
• Brain senses irritation due to the presence of a
  pollutant
• Brain sends efferent output that may/may not
  affect homeostasis
• CV system
• Pollutants may decrease blood O2 carrying capacity

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• Immune system
• Pollutants may cause inflammation and increase
  blood-borne immune factors
• Respiratory system
• Pollutants may
• Increase respiratory rate
• Reduce pulmonary function
• Exacerbate asthma and nasal allergies
• Increase bronchoconstriction and airway
  resistance decrease VO2max
• Decrease exercise performance

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Tests of Pulmonary Function (PFT)

• Forced expiratory volume (FEVt) the volume of
  air exhaled by a maximal effort during a specific
  time period (e.g., 1 sec FEV1)
• Forced vital capacity (FVC) the volume of air
  that can be expelled from the lungs during a
  maximal effort following a maximal inspiration
• Forced midexpiratory flow (FEF) the average rate
  of airflow over the middle half of the FVC.

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• Airway resistance (Raw) the difference between
  the pressure in the alveoli and the mouth,
  divided by the rate of air flow
• Diffusing capacity of the lung (DL) a measure
  of the lungs ability to move a gas from the
  alvioli into the capillary bloodstream carbon
  monoxide is the gas most commonly used to measure
  DL

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Air Pollution and Physical Performance

• Primary pollutants
• Those that exert their physiological influence
  directly from the source of pollution
• Carbon monoxide, nitrogen oxides, sulfur oxides,
  and particulates
• Secondary pollutants
• Formed by the interaction of primary pollutants
  with other compounds, ultraviolet light, or with
  each other
• Aerosols, ozone, and peroxyacetyl nitrate

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Carbon Monoxide (CO)

• Most significant primary pollutant
• Alters the ability of RBCs to carry O2
• HbCO carboxyhemoglobin
• Increase HR and VE submax
• Percent decrease of VO2max .91(HbCo)2.2
• Cardiac function decrements, visual impairment,
  headache, nausea, muscular uncoordination,
  syncope, coma, respiratory failure, death

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Nitrogen Dioxide (NO2)

• Released during heavy motor vehicle or aircraft
  engine combustion, fire fighting, and cigarette
  smoking
• Absorbed by the mucus membrane of the
  nasopharyngeal cavity
• When inhaled in high concentrations, pulmonary
  dysfunction may persist for 2-14 years.
• Diminished exercise tolerance time,
  breathlessness during exertion

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Sulfur Dioxide (SO2)

• Sulfur containing fossil fuels
• Acute bronchial tube constriction increased
  resistance to air flow
• Some, not all individuals show significant
  decrements in lung function following low levels
  of S02 exposure
• The threshold of effects on performance lies
  between 1.0 and 3.0 ppm SO2
• At 5.0ppm, decreases occur in expiratory flow,
  tracheal-bronchial clearance of mucus, and other
  measurements of lung function

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Fine Particulates

• Dust, acidic aerosols, tobacco smoke, wood smoke,
  pollen, bacteria, and sulfur-containing fuels
• No investigations to date have assessed the
  effects of particulates on submaximal or maximal
  exercise performance.

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Aerosols

• Secondary pollutant
• A suspension of ultramicroscopic solid or liquid
  particles in air or another gas smoke, fog or
  mist
• 2 studies no substantial changes in pulmonary
  function tests of clinical symptoms in either
  healthy or asthmatic test subjects

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Ozone (O3)

• Produced in nature by the action of ultraviolet
  radiation (UVR) on oxygen.
• Impairs pulmonary function, causes respiratory
  discomfort, and increases the number of reported
  clinical symptoms.
• Exacerbated during exercise! And a hot
  environment.
• Diminished exercise performance at concentrations
  of 0.24-0.35 ppm
• Subjective sensations of discomfort at lower
  levels
• Induces inflammation

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Peroxyacetyl Nitrate (PAN)

• Common constituent of smog
• Few studies no affect noted with exercise

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Medical Concerns

• Bronchial Asthma
• Illness that involves hypersensitive airways and
  an inflammatory reaction that narrows the
  respiratory tree.
• SOB, wheezing, coughing
• Fine particulates and exercise may stimulate an
  attack
• Nasal allergy substance enters the nose and
  stimulates the production of antibodies and the
  release of histamine inflammation, swelling,
  headache, itchiness.

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Recommendations for counteracting air pollutants

• 1. Listen to weather and news reports for daily
  updates of local air quality.
• 2. When ambient O3 levels are likely to be
  elevated, run in the morning or at night.
• 3. If high O3 or SO2 levels are anticipated, you
  should exercise for 4 to 6 days under the same
  exercise and environmental conditions that you
  anticipate during an upcoming competition or
  other lengthy exposure.

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• 4. Select training courses in parks or along the
  ocean, if possible, where breezes whisk away
  automobile and industrial exhausts laden with CO
  and other pollutants.
• 5. Minimize your exposure to pollutants while en
  route to an event.
• 6. Minimize the warm-up period, to limit your
  exposure to polluted air
• 7. Avoid congested highways and intersections
  during training, stay at least 10-15 m away from
  the exhaust pipes of cars and trucks and consider
  wind direction so that you ride or run on the
  up-wind side of the rode.

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• 8. Consider the effective dose (ED) of training
  sessions. ED O3VEExposure time
• 9. Daily air-quality reports rate the effects
  that local pollutants hae on your health. Do not
  exercise on days that are rated as unhealthy or
  hazardous
• 10. Stop exercise immediately and seek medical
  advice if you experience symptoms such as
  tightness in the chest, coughing, or wheezing.
• 11. Indoor environments often contain lower
  pollutant levels than outdoor sites
• 12. Sidestream smoke from the tip of a cigarette
  contains more CO than smoke that is directly
  inhaled.

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• 13. Asthmatics should observe a few
  nonpharmacologic precautions to minimize the
  duration and intensity of bronchospasm during
  exercise.
• Pool or other warm, humid environments
• Low intensity
• Wear a scarf or disposable respiratory mask in
  cold environments.
• Nose breath
• More gradual warm-up