YEARS

MEAN CONC of CH₄ (ppm)

Standard deviation (SD)of CH₄

Standard error (SE) of CH₄

MEAN CONC of O₃ (ppm)

Standard deviation

(SD) of O₃

standard error of O₃

MEAN CONC of NO₂ (ppm)

Standard deviation (SD) of NO₂

Standard error of NO₂

2003

1741.028

19.21

5.55

56.26

2.25

0.65

135.0419

64.63

18.66

2004

1738.174

11.76

3.39

57.25

2.27

0.65

141.1649

75.33

21.75

2005

1737.377

6.73

1.94

54.50

1.35

0.39

134.5924

67.06

19.36

2006

1731.105

10.63

3.06

57.14

3.43

0.99

143.5328

70.38

20.32

2007

1741.013

14.28

4.12

55.27

1.52

0.44

126.8056

57.45

16.59

2008

1743.488

12.81

3.69

58.56

3.11

0.89

129.6386

60.58

17.49

2009

1750.132

8.54

2.47

57.26

2.34

0.67

135.6946

59.09

17.06

2010

1746.159

6.59

1.90

58.03

3.42

0.99

127.5164

60.59

17.49

2011

1759.879

20.25

5.85

58.32

1.78

0.51

133.9337

51.27

14.79

2012

1773.897

11.76

3.39

56.80

1.98

0.57

132.7467

54.65

15.78