What common household item can be an indicator of humidity problems?

Mold and mildew growth serve as significant indicators of humidity problems within a household. These fungi thrive in moist environments and are particularly prevalent in areas where the humidity levels are consistently high. When humidity exceeds 60%, it creates an ideal environment for mold and mildew to develop, often leading to health issues and structural damage if not addressed.

Other options, while they may indicate various household issues, do not specifically signal humidity problems. Dust accumulation is more related to cleanliness and air circulation rather than moisture levels. Torn wallpaper may point to water damage but does not directly correlate with humidity levels. Cold drafts typically indicate issues related to insulation and air leaks rather than humidity itself. Thus, mold and mildew growth directly reflect the negative effects of excessive humidity, making it the most appropriate answer in this context.