Environmental influences refer to external factors that can affect hair health and contribute to hair loss. These can include pollution, UV radiation, climate conditions, and exposure to harsh chemicals or toxins. Understanding these influences is crucial in hair biology, as they can exacerbate genetic predispositions to hair loss or trigger conditions like telogen effluvium. Key distinguishing characteristics of environmental influences include their variability and the potential for both short-term and long-term effects on hair growth and retention.