Stanford research reveals the rapidly growing influence of wildfire smoke on air quality trends across much of North America. Wildfire smoke in recent years has slowed or reversed progress toward cleaner air. Tens of millions of people suffer degraded health, thousands die.

By spewing plumes of smoke laden with tiny toxic particles called PM2.5, wildfire smoke has slowed or reversed progress toward cleaner air in dozens of U.S. states, Stanford University researchers have found.

“We document a growing source of pollution that is changing trends in overall PM2.5 in a way that is completely unregulated and that will harm our health,” said lead study author Marshall Burke, an associate professor in the Stanford Doerr School of Sustainability.

No wider than a human hair spliced into 30 strands, PM2.5 can embed deep in the lungs and cross into the bloodstream. Even a few hours or weeks of exposure to elevated levels can trigger asthma attacks, heart attacks, and early death. Longer-term exposure can take months or years off your life expectancy…

“We’re starting to see the fingerprint of wildfire smoke on overall air quality trends over the entire country, not just in the western states where these fires are burning most often,” said study co-author Marissa Childs.

The new study extends a September 2022 analysis by Childs and Burke that looked at air quality, smoke pollution, and population data up to 2020. The initial study revealed a dramatic 11,000-fold increase in the number of people in the U.S. experiencing the most extreme levels of smoke pollution, and a 27-fold increase in the number of people living in areas experiencing unhealthy air at least one day per year.

According to the authors, the results underscore a need for a new approach to regulating air pollution as record-breaking wildfires and extreme smoke waves become near-annual events. “In the absence of further interventions,” the scholars write, “wildfire’s contribution to regional and national air quality trends is likely to grow as the climate continues to warm.”

This year’s out-of-control blazes released 2bn tonnes of CO₂ – probably triple the country’s annual carbon footprint.

The vast swaths of pine, spruce and larch forest that blanket much of Canada have been prized for generations. Not only do they provide a home to hundreds of species – including some of the most threatened in the country – but they also absorb more greenhouse gases than they emit, acting as a huge carbon sink.

This summer, however, as flames devoured one of the largest contiguous stretches of woodland on the planet, 2bn tonnes (2.2bn tons) of carbon dioxide were released into the atmosphere.

Emissions from Canada’s record-breaking wildfire season are probably triple the country’s annual carbon footprint, experts warn, as climate systems reach a “tipping point”...

Wildfires turn Canada’s vast forests from carbon sink into super-emitter