The answer has to be both since neither operate in a vacuum. They each support the other and neither could function without the other. It is a symbiotic relationship, though some might argue it's more parasitic.
To say that the working class doesn't support as much environmental pollution as do the capitalists is to miss an important point. The destruction is done to create a product and if no market exists for that product, the destruction can't continue for long. The working class always has the choice to avoid working for and purchasing from markets that promote great destruction and instead support less destructive markets. But since lowest price is usually given the greater weight over ethics in such choices, the most destructive of all markets will continue to be supported.
How is such a cycle broken? Can we rely on the election of politicians to do something about it, when politicians are among the richest of capitalists, seeing themselves as simply meeting demand or investing in the most profitable markets? Such a different direction is a simple conflict of interest for them in terms of both bottom line and power, and I think we've seen how likely that is to happen. That leaves the consumers, the majority of which are the working class. I see real potential for very positive change here, but it takes giving greater weight to ethics and less weight to lowest cost.