(Portland, OR) -- Greenhouse gas emissions in Oregon haven't changed much over the last ten years. The Oregon DEQ released its 2021 Greenhouse Gas Emissions Data that shows a decline in 2020, during the pandemic when travel was restricted. Last year, air pollution returned to 61 million metric tons. Pollution levels are seven-percent higher than they were in 1990. 35-percent of the pollution was from transportation, 29-percent from electricity generation, and 11-percent from natural gas combustion.