Annex 2

(Art. 11)

Concentration values for the assessment of interstitial air at polluted sites

¹In assessing the interstitial air of polluted sites, the concentration values in the following table apply. Where no concentration values are given in the table for emissions occurring at the site, e.g. odours or particles, the site is deemed to be in need of remediation if the emissions may lead to excessive ambient concentrations in accordance with the Ordinance of 16 December 1985¹on Air Pollution Control.

²For sampling and the performance of interstitial air analyses, the following apply:

1. Samples must be taken using ground gas detectors at a number of points representative of the pollution of the site. It shall be ensured that no extraneous air is included in the samples.
2. The interstitial air need only be analysed in respect of those constituents that are expected to occur at the site based on the historical investigation. If the analysis is confined to lumped parameters, the lowest concentration value of the individual substances shall be taken as the assessment criterion.

³Interstitial air samples may be dispensed with if it can be demonstrated by other means that the concentration values in the interstitial air cannot be exceeded, i.e. based on precise information concerning the composition and origin of the material at the site.

⁴The FOEN shall issue guidelines on sampling and on procedures for interstitial air analyses.

Substance	Concentration value
Inorganic substances
Mercury	0.005 ml/m3
Carbon dioxide	5000 ml/m3
Hydrogen sulphide	10 ml/m3
Organic substances
Petrol (free of aromatics)	500 ml/m3
Light petrol (aromatic content 0–10 by vol.-%)	500 ml/m3
Methane	10 000 ml/m3
Halogenated hydrocarbons
– Chlorobenzene	10 ml/m3
– 1,1-Dichloroethane	100 ml/m3
– 1,2-Dichloroethane (EDC)	5 ml/m3
– 1,1-Dichloroethene	2 ml/m3
– 1,2-Dichloroethene (cis and trans)	200 ml/m3
– Dichloromethane	100 ml/m3
– 1,2-Dichloropropane	75 ml/m3
– 1,1,2,2-Tetrachloroethane	1 ml/m3
– Tetrachloroethene (PERC)	50 ml/m3
– Tetrachloromethane (Carbon tetrachloride)	5 ml/m3
– 1,1,1-Trichloroethane	200 ml/m3
– Trichloroethene (TCE)	50 ml/m3
– Trichloromethane	10 ml/m3
– Vinyl chloride	2 ml/m3
Monocyclic aromatic hydrocarbons (BTEX)
– Benzene	1 ml/m3
– Toluene	50 ml/m3
– Ethylbenzene	100 ml/m3
– Xylenes	100 ml/m3
Polycyclic aromatic hydrocarbons (PAK)
– Benzo[a]pyrene	0.0002 ml/m3
– Naphthalene	10 ml/m3

Footnotes

1. SR 814.318.142.1 ↩