This paper examines the performance of two environmental regulation policies – emission taxes and absolute standards – in a vertical market where an upstream foreign monopolist sells a specific input to two downstream multiproduct firms that generate pollution in the domestic country. Specifically, we use a three-stage game to analyze and compare the two policies for regulating downstream pollution. In the first stage, the domestic government determines an optimal tariff and sets one of the two instruments (taxes or standards) by maximizing social welfare, in stage two, the upstream foreign monopoly sets its input price, and finally, the downstream domestic firms independently make their output and abatement decisions for profit maximization. We find that total emissions are lower under the absolute standard. Nevertheless, the tax dominates the standard in terms of domestic welfare, consumer surplus, and downstream multiproduct firms’ profits. Thus, the tax equilibrium leads to a win-win-win situation compared to the standard equilibrium. These results show the non-equivalence of emission taxes and absolute standards in regulating downstream pollution. The analyses suggest that a pollution tax is an economically and politically feasible policy.