The answers to this puzzle are a single word and a two-word phrase, both of which follow the word DARN.  The two-word phrase is a clever homophone of the single word.

This noxious cloud, it makes me wheeze.
I hate it! Darn _ _ _ _ _ _
                       _ _   _ _ _ _ _ _

Answer:

This noxious cloud, it makes me wheeze.
I hate it! Darn MIASMA
                          MY ASTHMA

Credit:
The Enigma 
NPL Magazine
December, 2019
FIRETRUCK