| Particulate
Matter (PM-10) Concentrations and Change, 1988-1997 (3) Technical
Note |
The map and
graph display annual average concentrations of particulate matter
(of particle size 10 micrometers or less.)
The particulate
matter map displays the average concentrations for a city or non-urban
county, and provides both the concentration in 1997 and whether
the concentration has been rising or falling over the last decade.
The graph summarizes trends for all monitors (i.e. not city or
county averages) over the past decade, showing the median sites,
poorer than average sites (worst 5 percent and 25 percent of all
monitors), and better than average sites (best 25 percent.)
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