The relative humidity in the piano's environment should be between 40% and 70%. If the relative humidity is below 40%, the environment is too dry for the piano; if it's above 70%, it's too humid. Maintaining a relative humidity between 40% and 70% is essential for the piano to function properly. Piano users should place a hygrometer beside the piano, regularly monitoring the humidity data to adjust the surrounding conditions to meet the piano's usage requirements.

When the environment for placing a piano becomes too dry (relative humidity < 40%), the wooden components of the piano will shrink and deform, causing the fastening screws of various parts to loosen, leading to unwanted noises and a feeling of looseness. Excessive dryness can also result in paint cracking, soundboard cracking, and unstable tuning. Prolonged exposure to an overly dry environment can cause significant damage to the piano.

When the environment where a piano is placed is too humid (relative humidity > 70%), it can also negatively affect the piano's use. Prolonged exposure to excessively humid conditions can cause the wood components to swell and deform, the felt in the transmission parts to expand and fall off, the parts to malfunction, and the strings to rust. It can also lead to a muffled sound, reduced volume, unstable pitch, and keys that move sluggishly. In severe cases, it can prevent the keys from functioning, rendering the piano unplayable.