| Reference Period | Smoke µg m-3 BS | Limit Values for Sulphur Dioxide |
| YEAR (median of daily values) |
68 | if smoke £ 34:120 if smoke > 34: 80 |
| WINTER (median of daily values October-March) | 111 | if smoke £ 51: 180 if smoke > 51: 130 |
| YEAR (Peak) (98 Percentile of daily values) | 213 | if smoke £ 128: 350 if smoke > 128: 250 |
| EC Directive Guide Values For Smoke And Sulphur Dioxide In Micrograms Per Cubic Metre | ||
| Reference Period | Smoke µg m-3 BS | Guide Values for Sulphur Dioxide |
| YEAR (arithmetic mean of daily values) |
34 to 51 | 40 to 60 |
| 24 HOURS (daily mean value) |
85 to 128 | 100 to 150 |
NOTE: The Limit and Guide Values given above for smoke according to the BS calibration are calculated from the original OECD calibration figures given in the EC Directive using the relationship: BS concentration = OECD concentration multiplied by 0.85