Passage Summary: People with allergies used special bedding that successfully killed off most of the dust mites in their beds, but they didn't actually feel any better.

Reasoning: Mite-proof bedding successfully reduced allergens in mattresses by 69 percent, yet allergy sufferers reported no improvement in symptoms, despite mattresses being the primary source of exposure.

Analysis: The paradox here is that a significant reduction in the 'main source' of an allergen resulted in zero symptomatic relief. To resolve this, we need a piece of information that explains why the 69 percent reduction wasn't enough to make a difference. Perhaps the remaining 31 percent of allergens in the mattress is still enough to trigger full symptoms, or perhaps other sources like carpets or clothing provide enough exposure to keep the symptoms active. Look for an answer that introduces an alternative source of exposure or a threshold effect for the allergen.