INVESTIGATION ON THE AMOUNT OF ODOUR NUISANCE CAUSED BY PIG FARMS IN THE NETHERLANDS

VAN ELST, T.¹, DRIESEN, K.¹, WOUTERS, P.², BRUSSELMAN, E.³, DEMEYER P.³

1 Olfascan, Belgium;

2 NVV, the Netherlands;

3 ILVO, Belgium

ABSTRACT: In the past very different values of pig odour nuisance were reported in the Netherlands. In order to get a better idea of the actual nuisance, an independent research was ordered by a Dutch pig-farmers association. In this project, on the one hand, odour emissions were determined using sniffing team measurements according to EN16841-2. Dispersion models were used to calculate the odour load for receptors in the surroundings. On the other hand, the odour nuisance was determined at the different receptor points, by means of a telephonic enquiry. Combining the output of these two methods, a coupling could be made between the degree of nuisance and the perceived odour concentration. One of the purposes of this study was to derive a proposal for a new odour standard. This however could not be done, since only very low percentages of nuisance were communicated in the residential areas. This could indicate that the existing regulatory system in the Netherlands, together with an efficient rural planning, led to an acceptable situation around the investigated farms. The difference between these results and a former study could probably be explained by the difference in approach of questioning people during the respective surveys.

Keywords: Odour nuisance, Pig Housing, Dispersion Modelling, Sniffing Team Measurement, EN16841-2

INTRODUCTION: A study conducted in 2015 in the Netherlands (GGD, 2015)) indicated that the amount of nuisance caused by pig farms could be higher compared to previous studies (PRA, 2001). Instead, according to NVV (a Dutch pig-farmers organisation), the amount of nuisance was thought to be lower instead of higher. Therefore, NVV ordered an independent research that was executed in 2015-2016.

1. MATERIAL AND METHODS: In this research project, the methodology was followed as used to build the Flemish odour regulation (Universiteit Gent, 2000). In the Netherlands, a subdivision is made between so called ‘concentration zones’ and ‘non-concentration zones’. In the concentration zones, cumulative effects can be expected due to the ubiquitous presence of intensive husbandry. For this research project, five representative and for the Netherlands typical pig farms were selected, three in

‘concentration zone’ and two in a ‘non-concentration’ zone. During selection of the cases, special attention was given to the presence of enough houses downwind the farms to perform the measurement of odour nuisance by means of telephonic enquiries.

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During summer and winter period, ten sniffing team measurement cycles according to EN16841-2 (CEN, 2016) were executed around the farms to determine their global odour emission strength. In this method, at least two experienced panel members, who fulfil the criteria of being a EN13725 panel member, traverse independently the plume, while conducting single measurements (observations during one inhalation) at frequent intervals.

The plume direction is traversed at different distances from the source; the crossings can be started far away from the source and heading to it, or vice versa (see Figure 1).

These crossings include traverses at distances where no recognizable odour is detected.

A transition point is defined as the point halfway between an adjacent odour absence point and odour presence point for the odour type under study. In order to prevent possible adaptation effects causing incorrect observations, the transition points in the dynamic plume method are only determined while entering the plume, and not while exiting.

The maximum plume reach estimate is determined as the distance along the plume direction between the source and the point halfway from the furthest crossing where odour presence points were recorded and the first crossing where only odour absence points were recorded.

Figure 1 shows schematically the two possible routes to determine the odour plume extent. This extent is defined as the smoothed interpolation polyline through the transition points, the source location and the location determined by the maximum plume reach estimate.

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The odour emission rate of the pig farm under study is calculated on the basis of the recorded plume extent, the source characteristics and the local meteorological conditions during the plume measurement.

To underline the differences between the field measurement and the olfactometric measurement, the odour emissions calculated on the basis of the plume measurement are expressed as sniffing units per second (su.s^-1) instead of odour units per second (ouE.s^-1). A very important difference between su and ouE is the fact that the odour observation during sniffing team measurements concerns the identification of a recognizable odour, while in the olfactometric laboratory measurements detectable odours are observed. Typically 1 su.m^-³ corresponds with a concentration between 1 ouE.m^-³ and 5 ouE.m^-³. One sniffing unit per cubic meter can be defined as the odour concentration at the border of the plume. This means that in every transition point the odour concentration can be defined as 1 su.m^-³.

The mean odour emission values of the ten measurements cycles were used to calculate the odour load for each receptor (house) in the surroundings, comparing Dutch and Flemish dispersion models.

On the other hand, the odour nuisance was determined at the different receptor points, by means of a telephonic enquiry. In order to obtain unbiased answers in this enquiry, odour was not the main focus during the questioning: people were asked about their general satisfaction with their living environment during the last year; odour was one of the many aspects that were considered.

2. RESULTS: The sniffing team measurements and the back-calculation to obtain the total odour strength of the source resulted in different values when different models were compared. Emission factors per animal were calculated and compared with existing factors determined with dynamic olfactometry (EN13725). Some values were comparable, others differed importantly. The emission factor derived from the sniffing team measurements however either coincides with the other factors or is an average of the other ones.

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Figure 2. Comparison of emission factors per animal per s

Around the five pig stables, in total 784 valid questionnaires were obtained. Only 0,3%

indicated the observed pig smell as being very annoying; 2,9% judged the situation as annoying. 96,8% of the receptors observes no smell at all or judged the odour climate as not annoying.

Applying this methodology in Flanders, the combination of the degree of nuisance and the perceived odour concentration resulted in a relationship able to predict nuisance based on the odour concentration present. In this study, no such coupling could be made due to the very low nuisance percentages. This could indicate that the existing regulatory system in the Netherlands, together with an efficient rural planning, led to an acceptable situation around the investigated farms.

The difference between these results and the former study (GGD, 2015), where much higher percentages of observed nuisance were reported, can probably be explained by the difference in approach of questioning people during the respective surveys: in the

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regulatory system in the Netherlands, together with an efficient rural planning, led to an acceptable situation around the investigated farms.

The use of sniffing team measurements instead of dynamic olfactometry appeared to be a valid alternative. Consensus however is necessary on the use of models, since different models result in different conclusions. European harmonisation in dispersion modelling would be a very valuable next step.

REFERENCES:

GGD, 2015. Geurhinder van veehouderij nader onderzocht: meer hinder dan Handreiking Wgv doet vermoeden?

PRA, 2001. Geurhinderonderzoek stallen intensieve veehouderij

CEN, 2016. Ambient air - Determination of odour in ambient air by using field inspection - Part 2: Plume method (EN16841-2)

Universiteit Gent, 2000. Onderzoek geurnormering. Ontwikkelen van methodologie voor opstellen van geurnormering per bedrijf – evaluatie van de toegepaste methodologie.

Opdrachtgever: Ministerie van de Vlaamse Gemeenschap, AMINAL, afdeling

Algemeen Milieu- en Natuurbeleid

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