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Clinical Scenario 1
A 12-year-old girl arrives at your office with her mother for an evaluation of the child's asthma. The mother reports that yesterday her daughter developed chest tightness and shortness of breath at soccer practice. A couple of puffs on her albuterol inhaler relieved the symptoms and allowed her to finish the practice. Rescue medication was needed again after dinner, and the girl woke up during the night and this morning with wheezing and shortness of breath. A mild expiratory wheeze is still perceptible. The mother says generally her daughter has been doing fine since starting a daily regimen of inhaled corticosteroids six months ago. There have been only two episodes of wheezing and both of them have been during the nights following soccer practices on Code Red ozone air quality days. The mother asks you, "Do you think ozone caused her wheezing? Should I make her skip practice if it's a Code Red air quality day? Is it safe for her to go out at all on those days?"

1. Ozone is a known trigger for exacerbating asthma. As with other triggers, some individuals are more likely to be affected by ozone than others.  For each individual, the increased likelihood of having an asthma attack is influenced by baseline asthma status, by individual sensitivity to ozone, and by the dose of ozone inhaled (dose = the product of concentration, minute ventilation, and duration of exposure).  An individual whose asthma is quiescent, who has historically not had exacerbations on days when ozone levels are high, and who will be exercising only for a short time on a Code Orange day is less likely to have an ozone related asthma attack than is an individual with a recent viral upper respiratory infection, who is known to be sensitive to ozone, and who will be performing intense, prolonged outdoor exercise on a Code Red day.

2. Balanced response. There is no single "correct" course of action for all individuals with asthma on Code Orange or Red days. Rather the potential costs and benefits of any action must be weighed.  On the one hand, physical activity has obvious health benefits, and participation in a particular activity may be of importance to an individual. On the other hand, ozone exposure can increase the probability of an asthma attack.  Those with poorly controlled asthma or who are known to be particularly sensitive to ozone exposure will probably benefit more by reducing exposure or increasing medication use than those who are less sensitive to ozone.  All asthmatics with an Asthma Action Plan should carefully monitor their asthma status and follow the recommendations of their plan for any sign of worsening asthma.   
3. Exposure reduction. As with other agents that are known to exacerbate asthma, reduction of exposure to ozone is likely to reduce the probability of an asthma attack.  By reducing the dose of ozone inhaled, exposure can be reduced on heavily polluted days. Because indoor levels are usually only 20% to 80% of outdoor levels, reducing time spent outdoors or reducing the level or duration of outdoor activity during the times of day that ozone levels tend to be highest in your area can be effective measures.  For organized sports, practices can be held at traditionally less polluted times of day and activities can be reduced or shortened on more polluted days.  Anyone known to respond adversely to ozone should include exposure reduction in his or her Asthma Action Plan.

4. Medication. Because no information specific to treatment or prevention of ozone-induced asthma exacerbations is available, one should probably approach the medical management of asthma during high ozone seasons as one would approach exposures to other asthma triggers. One would likely treat the individual with an occasional exposure differently from an individual attending a two-week soccer camp with long, intense workouts every day during the high ozone season.  Although there is some evidence that antioxidant (Vitamins C and E) supplementation in individuals with asthma can modestly reduce the neurally-mediated lung function changes due to ozone exposure, such treatment does not appear to reduce the inflammatory response to ozone, and there is no evidence that it would reduce asthma attacks.  There is some evidence that regular treatment with inhaled steroids results in a blunted inflammatory response to ozone exposure without an effect on immediate lung function and symptom changes.  Whether this reduction in the inflammatory response would result in a decreased probability of a later asthma exacerbation has not been addressed.