From a reading test on IELTS PTE Online titled "Allergy Testing,

A person does not become allergic to a particular substance until after the first exposure. However, in some cases, even trace amounts of a substance, such as peanuts or seafood in a mother's breast milk, can cause an allergic reaction in a subsequent exposure.

Does this "exposure" mean

[uncountable] exposure (to something) the state of being in a place or situation where there is no protection from something harmful or unpleasant

Source: Oxford Learner's Dictionaries

If it is, why before the second "exposure" has "a"? Because according to the Longman Dictionary, it is an uncountable noun.

  • Exposure is used here in the sense of an event of exposure. The first reference talks of "first exposure," which itself suggests there could be more "exposures," i.e., incidents of exposure. HTH. It's a general phenomenon and is nothing specific to "exposure" per se.
    – Kris
    Commented Feb 22, 2019 at 8:52
  • The Q is based on an incorrect interpretation of the sentence.
    – Kris
    Commented Feb 27, 2019 at 9:23

1 Answer 1


Answer: The correct term is count noun and noncount noun. Some nouns can be both. Exposure is one of those nouns.

The usage is correct in the paragraph in both sentence one and two.

Source: Check out MacMillan Dictionary at https://www.macmillandictionary.com - you may need a better dictionary.

Definition for "exposure" showing when this noun either a count noun, a noncount noun, or both is at this link:


Excellent source. College University recommended.

Confusion over when to use determiners "a" or "an"

Use a, an, and the where they are required. [With singular count nouns:

  • Simple rule: Use "a" before words beginning with consonant sounds, including those spelled with an initial pronounced "h" and those spelled with vowels that are sounded like consonants (a historian; a one o'clock appointment) ["one" sounds like "w," etc.] Use "an" before words that begin with vowel sounds, including those spelled with an initial silent h [an organism, an L (sounds like "El" or the e vowel when pronounced. (Little Brown Handbook, 11th Ed. P. 865, Pearson Education, 2010. Book. /LBH/)

Sentence two: subsequent + exposure makes this a compound subject. Using "a" to introduce "[s]ubsequent exposure" is correct. (LBH Pg. 231)

Hope this helps.

  • Could be simpler than that. See my comment at OP.
    – Kris
    Commented Feb 22, 2019 at 8:51
  • Your comment doesn't answer the poster's question(s). He states his dictionary lists "exposure" as a noncount noun. It's best to answer all his questions or reject it as not applicable here.
    – Steve B053
    Commented Feb 22, 2019 at 9:05
  • 2
    He doesn't seem to be confused. He seems to have a poor dictionary. Is he a Engl as 2nd Lang student? He's smart enough to try & apply grammar rules to a noun. Don't count him out.
    – Steve B053
    Commented Feb 22, 2019 at 9:19
  • 1
    I agree about needing a better dictionary. The (original) OED.COM lists 'exposure' as a count noun, and gives as examples "1796 E. Burke Let. to Noble Lord in Wks. (1815) VIII. 44 'Whatever in his pedigree has been dulcified by an exposure to the influence of heaven.'" and "1802 W. Paley Nat. Theol. xvi. 304 'So unusual an exposure of the globe of the eye.'" oed.com/view/Entry/66730?redirectedFrom=exposure#eid Commented Feb 22, 2019 at 15:51
  • 1
    @SteveB053 I'm not sure why you replied to me on this answer, but I'm not the asker... user337359 is the asker :)
    – Andrew T.
    Commented Feb 23, 2019 at 10:24

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