For example, a green plant, green is its natural color. If it turns yellow during the growing period, it is unhealthy.
Snow is healthy snow. If it is polluted by acidic substances, it will turn into yellow snow.
People are the same. For China people, black hair is a healthy color before getting old, but your hair turns white when you are young (except when you dye your hair and wear a wig). Does this mean that you are healthy?