When external pollution and treatment costs are included in the production cost of the
product, the supply curve intersects

When external pollution and treatment costs are included in the production cost of a product, the supply curve shifts outward because it now takes a higher cost of production to produce the same quantity of the product. By including these additional costs, the price must increase for producers to maintain the same level of profits. As the price rises, the demand shifts left and intersects with the supply curve at a higher price.