The deviation from the worldwide trend was strongest in the Pacific north-west, where wildfire risks are high during that month, but the effect lingered in data collected in areas across the country and into the north-east of the North American continent. The scientists found that this not only affects atmospheric carbon monoxide, but was found closer to the Earth’s surface as well. In August – when CO was expected to be driven to its lowest points – there were instead spikes. In a more recent period the researchers analyzed, from 2012-2018, a new trend began to emerge. Prior to 2011, the regions fell in line with this pattern and levels of the pollutants peaked in the spring and waned in late summer. Carbon monoxide levels in the atmosphere follow a seasonal flow, driven to ebb and increase through a photochemical process. But across North America, the scientists found that August was an outlier. Globally, carbon monoxide concentrations receded by half a percentage point a year over the 16-year study period. The deviation from the annual cycle, she said, “is telling us that fires are compromising the ability of the atmosphere to self-clean”. Her team, which also included scientists from across the country and around the globe, found that the dangerous pollutant peaks in August when fires are typically raging in the region, but dips during other months. Though the scientists relied on carbon monoxide data to guide them, the contaminant also provided a framework to understand how other sources of pollution might be tied to the flames. Looking at carbon monoxide, a trace gas emitted during fires, researchers analyzed the impact on atmospheric chemistry from 2002 to 2018, Buchholz explained. “Our research contributes to the growing body of research that shows that fires – in particular Pacific north-west region fires – are becoming more important for North American air quality” said Dr Rebecca Buchholz, a project scientist at National Center for Atmospheric Research. But scientists are increasingly finding that the fires may be part of a feedback loop that could accelerate the change in conditions and that health impacts officials have long warned would worsen with climate crisis, may in fact already be here. As the American west faces increasing threats from big blazes that are fueled by a climate that’s growing warmer and drier, researchers have documented the impact of smoke on public health.
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