Possible Clues:

• Doc's colleague's reduced drug for cold symptom
• Sudden involuntary exhalation
• React to an allergy
• 'Gesundheit' preceder
• It may signal a cold snap beginning to affect the audience's leg joints
• Violent, involuntary expulsion of breath
• Could be cold, by the sound of it
• A sternutation
• Blow that for a cold spell!
• Nasal eruption due to cold