IOP

Number of PEMs in Operation

Number of Sources Detected

Average (ng/m³)

Median (ng/m³)

Standard

Deviation

1a

9

5

371

343

60

2a

11

7

165

86

223

3a

8

5

82

76

32

4a

11

9

308

262

185

7a^*

16

11

60

30

36

8a^*

12

10

33

30

6.7

2b

11

18

82

30

86

3b

16

15

203

181

168

4b

15

7

330

281

214

5b

15

8

441

273

651

6b

14

10

220

174

183

7b

15

14

272

159

251

8b

15

7

187

154

111

9b

15

5

136

119

48

10b

15

12

81

88

47

Average^**

221

171

174