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Table 2 Descriptive statistics for environmental variables, May 2003 – Jan 2006

From: Short-term effects of ambient particulates and gaseous pollutants on the incidence of transient ischaemic attack and minor stroke: a case-crossover study

 

Manchester

Liverpool

Environmental variable

Mean

SD*

Q1

Median

Q3

Mean

SD*

Q1

Median

Q3

CO†(mg/m3)

0,4

0,2

0,28

0,35

0,43

0,19

0,11

0,15

0,15

0,2

PM10 †(μg/m3)

22,6

8,8

16,67

20,33

26

20,57

8,3

15

18,5

23,5

NO†(μg/m3)

16,9

22,1

7,2

10,2

16,2

8,05

11,49

3,5

5

8

NO2 †(μg/m3)

32,5

12,4

23,5

30,5

39,25

21,3

11,13

12,5

18,5

27

SO2 †(μg/m3)

2,8

2,8

1

2

4

6,13

3,35

4

5,5

8

Ozone(μg/m3)

37,4

16,71

26,67

38

48

47,78

17,5

37

49

60

Temperature(°C)

10,72

5,06

7,02

10,92

14,58

11,25

4,78

7,75

11,42

15,09

Relative humidity, %

79,69

8,36

73,84

80,28

86,17

82,81

8,15

77,61

83,3

89,25

  1. * SD: standard deviation; Q1: 25th percentile; Q3: 25th percentile.
  2. † PM 10: mass concentration of particles less than 10 μm in aerodynamic diameter; CO: carbon monoxide, NO: nitric oxide; NO 2: nitrogen dioxide; SO2: sulphur dioxide.
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Environmental Health

ISSN: 1476-069X