US Air Quality Gradebook

Ambient Gradesheets

Autumn Leaves for US Air Quality Gradebook - Ambient Gradesheets


Good air quality is necessary to avoid harmful health effects.  According the Environmental Protection Agency, poor air quality causes visual impairment, reduced work capacity, reduced manual dexterity, poor learning ability, difficulty in performing complex tasks, neurological impairments, seizures, mental retardation, behavioral disorders, changes in airway responsiveness, respiratory illness, susceptibility to respiratory infection, lung inflammation, aggravation of respiratory conditions, chest pain, cough, decreased lung function, increased hospital admissions, aggravation of

cardiovascular disease, and premature death.  The EPA has “primary standards” to protect the public against these health effects.  These standards set concentration limits for six “criteria pollutants,” namely carbon monoxide (CO), lead (Pb), nitrogen dioxide (NO2), ozone (O3), particulate matter (PM), and sulphur dioxide (SO2).


Hyperlinks below bring up gradesheets for US counties relative to these primary standards.  The following are concentration limits associated with grades on the sheets:



Grade Levels

[1-hr, 8-hr, and 24-hr are averaging periods; Q = quarterly average concentration; A = annual; PM10 = particulate matter smaller than 10 micrometers; “2nd Max” allows “tossing out” one averaging period; ppm = parts per million; µg/m3 = micrograms per cubic meter.]



The grade "A" represents the Best/Cleanest ambient concentrations in the US, and "F" the Worst/Dirtiest in the US.  The grades reflect the statistical

distribution of base-10 logarithms of the ambient concentrations for all measured US counties, as in the following table:



Grade Levels on Bell Curve



The statistical procedure makes each grade limit a common multiple of the next lower limit.  For example, the upper grade A limit for CO 8-hr before "rounding up" is 1.287 ppm, and the common multipler for the CO 8-hr distribution is
1.701 = 10(one standard deviation).
The unrounded upper limit for

grade B is 1.287 x 1.701=2.189,
grade C is 2.189 x 1.701=3.723, and
grade D is 3.723 x 1.701=6.333.


When applied individually to the 10 ambient concentations, the procedure results in the following percentages of measured counties in the grade levels:



Ambient Grade Distributions

[N = Number of measured US counties.  Example: Grade D for CO 1-hr means at least 72.5% of the 251 measured US counties have smaller CO 1-hr ambient concentrations (72.5% = 8.0% A's + 15.1% B's + 49.4% C's).]



A county's "ambient" grade is the grade of its worst individual pollutants, which are highlighted in bold italics.


References for air quality include the Environmental Protection Agency's National Air Quality and Emission Trends Reports at online reference  An online reference for year 2001 ambient levels is EPA's AIRData at  Scorecard at discusses air quality for specific locales.  NASA has a global satellite view of CO concentrations, which can be seen here.

Click on a state to view a sheet showing grades for year 2001 ambient air measurements and the resultant county ambient grades.  A blank in the gradesheet means there were no measurements of that pollutant.  Missing counties had no ambient air measurements.  One can use the gradesheets to determine what pollutants caused a county have the grade it does.  A county's grade may be based on few measured pollutants.  After viewing a gradesheet, click the browser's back button/arrow to return to this index page.







California, Alameda-Sutter

California, Tehama-Yolo




District of Columbia





















New Hampshire

New Jersey

New Mexico

New York

North Carolina

North Dakota





Puerto Rico


Rhode Island

South Carolina

South Dakota





Virgin Islands



West Virginia





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Go to Creative Methods Homepage - Scientific Analyses of Fundamental Issues Go to US Air Quality Gradebook - from Go to US Air Quality Gradebook - Air Quality Maps by US County Go to US Air Quality Gradebook - Air Pollutant Emission Gradesheets
Go to US Air Quality Gradebook - Ambient Gradesheets for Criteria Air Pollutants Go to US Air Quality Gradebook - A Molecular View of Air Quality Go to US Air Quality Gradebook - Air Pollution Sources

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Abstract: At Creative Methods, we try to “step outside the box” and look at fundamental issues in our world with new perspective.  Under the issue Air Quality, we present EPA data as maps and gradesheets that grade US counties A to F for 21 EPA measures of air quality.  The topics of air pollution and environmental health are serious issues in the US, and result in pollution health effects including headache, respiratory impairment, neurological impairment, mental impairment, asthma, lung disease, chronic fatigue, immune system dysfunction, premature aging, and reduced longevity.  Environmental science monitors air pollutant emissions, as well as criteria air pollutant concentrations through ambient monitoring.  The US Air Quality Gradebook (“AirGrades”) grades both emissions and ambient concentrations on maps and gradesheets, and assigns resultant composite scores to US counties.  Air pollutants include carbon monoxide, CO; lead, Pb; nitrogen dioxide, NO2; nitrogen oxides, NOx;

volatile organic compounds, VOC; ozone, O3; particulate matter smaller than 10 micrometers in size, PM10; particulate matter smaller than 2.5 micrometers in size, PM2.5; ammonia, NH3; sulphur dioxide, SO2; hazardous air pollutants, HAP; diesel emissions; and acrolein.  Air pollution point sources include electric power generating facilities and industrial plants.  Area source emissions include wildfires, forest fires, open burning, permitted burning, structure fires, and fugitive dust.  Mobile sources include highway and off-road vehicles with internal combustion engines such as automobiles, trucks, trains, airplanes, snowmobiles, and all terrain vehicles (ATVs).  The maps, gradesheets, and source sheets demonstrate that clean air is at a premium in the US.  Sites presenting issues on health and the environment related to those presented under the topic Air Grades by Creative Methods at are Scorecard at and the Environmental Protection Agency, EPA, at