Control of Lead at Work Regulations (Northern Ireland) 1998

2.  Biological monitoring shall be carried out at intervals not exceeding those set out below—

(a) in respect of an employee other than a young person or a woman of reproductive capacity, at least every 6 months, but where the results of the measurements for individuals or for groups of workers have shown on the previous two consecutive occasions on which monitoring was carried out a lead in air exposure greater than 0·075 mg/m³ but less than 0·100 mg/m³ and where the blood-lead concentration of any individual employee is less than 30 μg/dl, the frequency of monitoring may be reduced to once a year;

(b) in respect of any young person or a woman of reproductive capacity, at such intervals as the relevant doctor shall specify, being not greater than 3 months.