another weird dream---last night

i dreamt i was at a party in someone's backyard and i was hanging out at the end by an area with a cement ground. From my view there were people dancing and socializing on the grass/yard. I noticed that from the grass emanated something and people started gasping for air and panicking. The people standing on the cement area were fine. From my viewpoint I saw the invisible substance come from within the grass and upward and affect the people on the grass.