Air Quality: Particulate Matter
Whether
you can see it, or not, the air around us carries dust particles. The
particles can range in size from a grain of sand down to molecular
dimensions and be of wide-ranging compositions.
Particulates
originate from many different industrial and transportation points, as
well as from natural sources. Similar to ozone, particulates can be
carried on prevailing winds over great distances. For scientific
purposes, airborne particulate matter is classified according to its
aerodynamic size. The SLEA has focused on the monitoring of fine
particulates, or respirable particulates (PM2.5), which are
2.5 microns or less in diameter and are capable of penetrating deep into
a person’s respiratory system. PM2.5 has also been added to
the Ontario Air Quality Index Program, reaffirming the connection of
fine particles to the formation of smog and its associated human health
concerns. The Tapered Element Oscillating Microbalance Method for
real-time continuous measurement of PM2.5 is relatively new.
Having been developed and refined over the past 12 years, the method is
used by Environment Canada and the Ontario Ministry of the Environment.
* 1 microgram ( g) = one-millionth gram
Annual mean levels measured at the two monitoring sites.
