For a driver aged 20 or over who does not hold a zero-alcohol or alcohol-interlock licence, what is the maximum permitted breath-alcohol reading? Enter the number in micrograms per litre of breath.

Explanation

The ordinary age-based ceiling is 250 micrograms per litre of breath for a driver aged 20 or over who is not subject to a special zero limit. A reading beginning at 251 enters the infringement-level range, while a zero-alcohol or alcohol-interlock licence permits no alcohol at all.