In briefAir pollution, airborne allergens, and changing weather conditions—alone or in combination—can hinder physical activity. In any active individual, high ozone levels can cause restrictive lung dysfunction, and high carbon monoxide levels can impair oxygen delivery. Sulfur dioxide worsens nasal symptoms in people who have allergies and causes bronchospasm in those who have asthma. Airway irritation from fine particulates can lead to bronchospasm. Atopic individuals suffer from the well-known effects of fungi and pollen. If a change in exercise routine or activity doesn't relieve symptoms, pharmacologic treatment may include antihistamines, immunotherapy, inhaled corticosteroids, and/or inhaled beta-2bronchodilators.