Table 32.1 - Relative natural and anthropogenic contribution (per cent) to tropospheric ozone precursor emissions in 1990
Sources |   | CO | CH4 | VOCs | NOx |
---|---|---|---|---|---|
Global | Anthropogenic | 62 | 63 | 10 | 76 |
Natural | 38 | 37 | 90* | 24 | |
Northern hemisphere | Anthropogenic | 72 | 73 | 16 | 84 |
Natural | 28 | 27 | 85* | 16 |
Note: * Including isoprene and terpenes.