Standard deviation) time from collection until being frozen in the laboratory for samples with no observed mould was 2.9 (3.0) days. In comparison for low level mould it was 4.9 (3.6) days (crude mean difference compared with no mould; 95 confidence interval (CI) = 1.7; 1.4 ?2.1 days), for medium level mould it was 7.4 (4.9) days (3.9; 3.4 ?4.3), and for high level mould 11.4 (10.7) days (7.1; 6.