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

1735.398

21.83

6.30

55.9953

2.00

0.58

110.446

48.70

14.06

2004

1730.427

13.87

4.00

57.2429

2.16

0.62

115.194

51.06

14.74

2005

1731.348

8.16

2.36

54.3009

1.22

0.35

113.295

53.17

15.35

2006

1723.773

14.90

4.30

57.0647

3.34

0.96

115.726

51.91

14.99

2007

1734.091

15.18

4.38

55.0859

1.34

0.39

95.2234

35.82

10.34

2008

1737.264

13.49

3.89

58.6348

2.91

0.84

103.759

49.51

14.29

2009

1743.735

12.19

3.52

57.0171

2.08

0.60

107.113

46.93

13.55

2010

1742.048

7.34

2.12

58.0992

3.44

0.99

105.718

48.65

14.04

2011

1752.863

21.21

6.12

58.2138

1.56

0.45

102.646

39.06

11.28

2012

1768.989

13.51

3.90

56.7082

1.68

0.48

109.667

49.98

14.43