![]() ![]() ![]() Ozone is a highly corrosive gas formed in the atmosphere from ambient “primary” pollutants reacting in sunlight. Ground-level ozone, commonly referred to as “smog,” is another air pollutant of concern in Washington state. Only changes in weather, such as with direct sunlight, strong gusts of wind, or the seasons, can reverse these conditions. Without a means for dispersing beyond the warm air layer, emissions accumulate in the lower atmosphere. Temperature inversions describe conditions in which cold surface level air becomes trapped and stagnates beneath a warmer, denser air layer above. In Washington, temperature inversions are common in the winter, particularly when snow covers the ground. While winter emissions are typically higher than summer emissions, adverse weather conditions, such as temperature inversions, can prevent polluted air from dispersing, further heightening air pollution levels. 3 During the winter months, urban cities in Washington commonly experience PM2.5 levels 3 to 5 times that of the levels experienced during the summer. An estimated 63 percent of particle pollution in the Puget Sound area in the winter is attributable to wood stoves and fireplaces (compared to 16 percent of emissions from motor vehicles). Such exacerbated seasonal conditions have already resulted in historic wildfire seasons in recent years, notably in 20 before that.īeyond the influence of wildfires, seasonal winter wood burning is cause for greatly elevated PM2.5 levels in the months from November to February. 2 Steep mountains, strong winds, longer summer seasons, and drier conditions contribute to Washington’s wildfire problem, and have illuminated a clear trend of what is likely to come. Wildfires are expected to become more frequent and severe with the planet’s warming climate, as are Washington’s smoky conditions. 1Ģ020 has been a record-breaking year for fires nationally as well as within the state, causing more than a week of “unhealthy” or worse air quality in numerous Washington cities such as Seattle, Tacoma, Everett, Bellevue, and Kent. Nationally, 71,500 fires burned 10 million acres in 2017, while 58,100 fires burned 8.8 million acres in 2018, and only 50,500 fires burned 4.7 million acres in 2019. These year-over-year improvements in Washington air quality correspond to a decline in the number of fires and acres burned during those years. This number rose to 78.5 percent in 2018 and 98 percent in 2019. Only 54 percent of Washington cities met WHO targets for annual PM2.5 exposure in 2017. ![]() The latter is the reason for year-to-year fluctuations. Washington’s PM2.5 spikes are often attributable to forms of incomplete combustion, such as winter wood burning and wildfires. PM2.5 is lumped from a variety of chemical compositions into a single category based on size for its ability to slip past the respiratory system’s defenses and cause a wide range of short- and long-term health effects, from coughing, shortness of breath, and chest pain to chronic diseases that contribute to early death. Wind-blown dust, soot and ash from wildfires, chemicals from industrial complexes, and the burning of fossil fuels all constitute common origins of PM2.5. PM2.5 describes airborne particles from a wide variety of sources (even natural ones) that measure 2.5 micrometers or smaller. Episodes of unhealthy air quality are usually the result of short-term PM2.5 and/or ozone pollution. Generally, air quality in Washington state is considered healthy. Why is the air quality so bad in Washington? ![]()
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