From: Identifying potential exposure reduction priorities using regional rankings based on emissions of known and suspected carcinogens to outdoor air in Canada
Percent contribution to total substance emitted
Substance
Airports
NPRI
Rail
Res gas
Res oil
Res wood
Roads
Arsenic
2
97
<1
0
1
Benzo[a]pyrene
65
35
Benzene
13
87
TCDD
6
94
Lead
88
10