The correlation between odor concentration and pollutants is complementary to olfactometric analysis.
Compounds to be considered depend on the type of plant being examined. Therefore, it is necessary to perform a previous study of the production process and raw materials present.
The most common classes of compounds are TOC, VOC, IPA and mercaptans.
Phases of activities are as follows:
- Collection of odor samples in parallel with chemical sampling;
- Analysis of both chemical and olfactometric samples;
- Comparison of chemical concentration values with olfactory perception thresholds present in the literature;
- Determination of synergy-masking reactions among various compounds as regards odor formation.
A starting point for the comparison between the results of chemical analyses and olfactory perception thresholds is chart 2 in Attachment 4 of Regional Parliament Decision dated 15th February 2012 – n. IX/3018. It is entitled “General Determinations regarding the characterization of gas emissions in the atmosphere due to activities having a strong odor impact”, and based on the study called "Measurement of Odor Threshold by Triangle Odor Bag Method" by Yoshio Nagata of the Japan Environmental Sanitation Center.
It is also important to consider what has been defined in Attachment A.4 of Instructions for the application of article 272-bis of Decree-Law 152/2006 as regards odor emissions in facilities and premises, edited by M.A.S.E.
