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Air Pollution: Exercise in the City

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 (f

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Air Pollution: Exercise in the City

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    1. Air Pollution: Exercise in the City

    2. 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

    3. 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

    4. 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

    5. 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.

    6. 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

    7. 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

    8. 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

    9. 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

    10. 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

    11. 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.

    12. 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

    13. 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

    14. Peroxyacetyl Nitrate (PAN) Common constituent of smog Few studies no affect noted with exercise

    15. 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.

    16. 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.

    17. 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.

    18. 8. Consider the effective dose (ED) of training sessions. ED = {O3}*VE*Exposure 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.

    19. 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

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