Those minorities get the worst of the air pollution and dangerous noise levels themselves. And you have to add the externality of everyone else being affected b

Those minorities get the worst of the air pollution and dangerous noise levels themselves. And you have to add the externality of everyone else being affected by the pollution before you weigh the costs and benefits. Of course landscapers shouldn't be expected to switch voluntarily when it puts them at a competitive disadvantage, it's a textbook case of externality needing regulations.