According to an Environment Canada special air quality statement , high levels of air pollution caused by the smoke emanating from forest fires in Quebec and northeastern Ontario plagued North Bay and the area over this past weekend and in the early part of this week, resulting in deteriorated air quality. See related:  Here's how to check for dangerous air quality levels in North Bay The air quality measuring website AQI  showed North Bay had the second-worst pollution ranking worldwide on Sunday .

https://www.baytoday.ca/local-news/health-unit-responds-to-some-faqs-on-poor-air-quality-7197642

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