contamination from plants and industrial facilities is another model. We are totally aggravated off by contamination however are not repaid by the market for this harm. A positive externalitv is the point at which a singular's utilization in a market builds the prosperity of others, however the individual doesn't charge the outsider for the advantage. The outsider is basicallyr getting a free items An illustration of this may be the loft over a pastry shop getting the advantage of satisfaction from smelling new baked goods each dav' Individuals who live in the loft don't repay the pastry kitchen for this advantage. [1]