Table 3

Missing data days and summary statistics of maximum daily pollutant levels in study period.
Variable (unit)
 Mean
 Standard Deviation
 Minimum/24 hr
 Maximum/24 hr
 AAQC†
 Number of Missing Days
SO2 (ppb)
 London
 3.35
 2.96
 0
 28.63
12

Windsor
 7.36
 5.06
 0
 37.50
 100/24 hr
 8

Sarnia
 9.72
 12.72
 0
 110.17
4








NO2 (ppb)
 London
 18.10
 7.86
 0
 53
54a

Windsor
 23.50
 7.59
 6
 50
 100/24 hr
 11

Sarnia
 16.85
 8.13
 0
 52
100c








O3 (ppb)
 London
 23.61
 12.50
 0
 77
7

Windsor
 20.62
 12.58
 0
 82
 80/hr
 6

Sarnia
 25.35
 11.86
 0
 76
54d








CO (ppm)
 London
 0.16
 0.30
 0
 3
9

Windsor
 0.60
 0.44
 0
 3
 3/hr
 5

Sarnia
 0.27
 0.29
 0
 1.4
87b

†Ambient Air Quality Criteria (Ontario Ministry of the Environment, 2000).

a Seven or more missing days in a row: 2000 – Jan. 7–31; Feb. 1–10

b Seven or more missing days in a row: 1998 – Dec 2–31; 1999 – Jan 1–31

c Seven or more missing days in a row: 1997 – Oct. 8–16; 1998 – Sept. 24–30; Oct. 1–31; Nov. 1–10

d Seven or more missing days in a row: 2000 – Nov. 8–16

e Seven or more missing days in a row: 1997 – Jan. 17–23

Fung et al. Environmental Health 2007 6:18   doi:10.1186/1476-069X-6-18

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