PRO stands for Pollution Return Officer or sometimes Pollution Registration Officer, depending on the industry. Simply put, PRO Authorisation is permission given to businesses to handle hazardous materials, chemicals, or waste safely and legally. Without this authorisation, a business can face fines, legal trouble, or even closure. Think of it like getting a school ID card. Without the card, you can't enter the school. Similarly, without PRO Authorisation, you cannot legally operate certain types of businesses in India.