Student or Learner
Children under the age of ten are at greatest rick from air pollution.
In this sentence, I think 'the' should come before 'greatest' but it didn't come. Sometimes I see 'the' is dropped but don't know why and when exactly. Anybody, could you pls answer for me?
Thanks for your time ^^
At risk (from/of) is an idiomatic expression meaning in danger of something unpleasant or harmful happening.
At the risk of is used to introduce something that may sound stupid or offend somebody.
(definitions from Oxford Advanced Learner's Dictionary).
So the writer of your sentence has omitted the to ensure that his superlative expression relates to the idiomatic expression.