Peanuts as a cause of your son's allergy at a ballgame is possible, but highly unlikely. Studies have been performed to deermine how much peanut protein can become airborne or aerosolized, and it is a very small amount (often too small to cause a reaction), and it does not travel far. Other causes of his symptoms may be dust, grass or smoke sensitivities. Pre-treatment with an allergy medication may help what are more likely to be allergy symptoms.