user: ### NOW ANSWER:
Question: Which Particulate size approaching 100% retention has a Usage of Semi Hepa and a Class of H12?
Columns: ['Usage', 'Class', 'Performance', 'Performance test', 'Particulate size approaching 100% retention', 'Test Standard']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Primary filters', 'G1', '65%', 'Average value', '>5µm', 'BS EN779']
SQL:

assistant: SELECT "Particulate size approaching 100% retention" FROM "Table" WHERE "Usage" = 'Semi Hepa' AND "Class" = 'H12';