This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.

Canada is facing another dangerous wildfire season, with burning forests sending smoke plumes across the provinces and into the U.S. again. The pace of the 2025 fires is reminiscent of the record-breaking 2023 wildfire season, which exposed millions of people in North America to hazardous smoke levels.

For most of the past decade, forecasters have been able to use satellites to track these smoke plumes, but the view was only two-dimensional: The satellites couldn’t determine how close the smoke was to Earth's surface.

The altitude of the smoke matters.

If a plume is high in the atmosphere, it won't affect the air people breathe – it simply f

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