During allergy season, sufferers know the drill: runny nose, watery eyes, sneezing up a storm. For the unlucky with asthma, symptoms might also include coughing and wheezing. However, asthma is not always caused by allergens like pollen and dust--nonallergenic asthma is brought on by a number of possible environmental or genetic triggers. Then there's the common cold, which also presents with similar symptoms. So what's causing your runny nose? In...