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Data Set #005

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About the Data

ABOUT MAXIMUM DAILY OZONE IN SAN DIEGO

Ozone (O3) is a compound of oxygen found both high in the stratosphere (the "good" ozone blocking harmful ultraviolet radiation) and low in the troposphere (the "bad" ozone that is the main part of photochemical smog). Ozone is a potential harmful chemical to humans, as it will interfere with the respiration, even at very low concentrations. Ozone causes inflammation of airways that can reduce lung capacity, and can result in permanent damage to lung tissue. The EPA has established a federal standard for ozone concentration in the lower atmosphere at .12 ppm (average concentration over 1 hour).

Air samples taken on Overland Avenue in downtown San Diego during June, July and August of 1998 were analyzed for ozone and compiled by the California Air Resources Board (CARB). The data were reported in several different fashions. Maximum daily concentration of ozone measured over a 1 hour period are given in the table and shown in the diagram.

The data can be displayed and analyzed using a histogram, which shows a skew symmetric distribution of maximum ozone values measured on 70 different days during the summer of 1998 in San Diego. Skew symmetric distributions are quite useful in illustrating to the student the differences between the mean, median and mode. The mean ozone maximum is much lower than the federal standard, however there was one day in August when the EPA standard was exceeded.

The choice of graphical representation can obscure or illuminate the data; students should learn that graphs are no substitute for the original data. Is there some way of graphically representing this data set to "hide" the one value that exceeds the federal standard?

Reference: Data were obtained from CARB's wonderful website, which is a very valuable resource for educators. Look under Air Quality Data: http://www.arb.ca.gov/html/aqe&m.htm

See also the South Coast Air Quality Monitoring District website for southern California: http://www.aqmd.gov

     
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View the Data

day in #

ozone (ppm)

71

0.053

72

0.050

73

0.038

74

 

75

0.043

76

0.038

77

0.047

78

0.062

79

0.051

80

0.046

81

0.031

82

0.034

83

0.039

84

0.060

85

0.057

86

0.045

87

0.067

88

0.068

89

0.097

90

0.094

91

0.067

92

0.044

93

0.040

94

0.023

95

0.027

96

0.040

97

0.036

98

0.081

99

0.105

100

0.040

101

0.065

102

0.040

103

0.047

104

0.038

105

0.057

106

0.085

107

0.090

108

0.065

109

0.054

110

0.049

111

0.054

112

0.086

113

0.076

114

0.057

115

0.063

116

0.042

117

0.052

118

0.041

119

0.042

120

0.050

121

0.048

122

0.043

123

0.044

124

0.050

125

0.065

126

0.071

127

0.057

128

0.042

129

0.047

130

0.042

131

0.067

132

0.067

133

0.125

134

0.115

135

0.054

136

0.075

137

0.075

138

0.065

139

0.037

140

0.045

   

mean ozone

0.0567

sigma

0.0204

min

0.023

max

0.125

Bin

Frequency

.02 - .03

2

.03 - .04

8

.04 - .05

21

.05 - .06

13

.06 - .07

12

.07 - .08

4

.08 - .09

3

. 09 - .10

3

.10 - .11

1

.11 - .12

1

.12 - .13

1

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