When silver tarnishes, it is a surface discolouration that causes the interaction of oxygen with silver. Although, silver may naturally react with oxygen and sulfur-based air pollutants to create a visible discolouration on the surface.
Even in low concentrations of pollutants in the air, average quality silver jewellery may tarnish. Another reason for the same is relative humidity, ambient temperature, gas concentration, etc. It would help if you never left sterling silver jewellery in your bathroom and were exposed to humidity from the shower. It is best to avoid wearing these statement pieces unless you cannot take due care of them.