Ground Level Ozone and PM2.5

Ground-level ozone and fine particulate matter (PM2.5), two key components of smog, are the pollutants of greatest concern in Ontario. Ground-level ozone (distinct from stratospheric ozone, which shields us from up to 99 per cent of the sun’s harmful high frequency ultraviolet rays) has been linked to negative impacts on human health and vegetation.

PM2.5 consists of fine particles measuring less than 2.5 microns in diameter that, when inhaled, can penetrate deep into the lungs. Studies suggest that there is no safe health threshold for these pollutants (i.e., they have potential health impacts at any concentration).

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• Back to Air Quality Monitoring and Reporting in Ontario – Fostering a False Sense of Security
• 2007/08 Annual Report Table of Contents

This is an article from the 2007/08 Annual Report to the Legislature from the Environmental Commissioner of Ontario. Click here for more information on the official document and its release.