Even in regions that are not strongly associated with wildfire, such as the southeast region of the U.S., wildfire pollution rates grew substantially during that time period. Over the study period, about 65% of the days that recorded pollution levels above the National Ambient Air Quality Standard could be attributed to wildfire smoke. “What our findings show is that wildfire smoke is offsetting a growing share of these hard-won improvements.” The study found that some regions were disproportionately affected by the smoke, including in the Northwest, where rates of pollution from wildfire more than doubled over that period. Recent studies have correlated wildfire smoke exposure with an increased risk of preterm birth, low birth weight and other negative outcomes such as stillbirth and some congenital anomalies.