if wattles are white and ventilation is fine the odd sneeze is nowt to worry about , if you see a bird sneezing , catch it hold it as normal put you ear between its back ( just behind it''s wings near base of neck ) you'l hear its lungs opening and closing , like little clicks , if sounds rattley then you have respirity , look at your ventilation / number of birds in section , and treat , for prevention i use respirity mist and bathsalts , and a herbal mix to keep under control