Air pollution impacts global warming by changing atmospheric chemistry, effectively producing ozone and destroying methane (greenhouse gases). We quantify these greenhouse gas changes with a specialized model that tracks the chemical impact of air pollutants over their lifetime. Our summertime Korean results, scaled to all air pollution, estimate that up to 30 % of tropospheric ozone production and 10 % of methane loss is caused by air pollutants, but this scaling overrates wintertime pollution.