Advanced psichometrics based on citizen science. A history, a new standard, a European project and a case study in Chile.

For more than 30 years, technical standards and criteria have been developed to quantify odor concentrations, odor characteristics such as intensity, hedonic tone and odor impacts. Within these 'traditional methods', and most of the odor regulations around the world, the capacity and knowledge of citizens are largely excluded from the analysis. However, involving citizens in gathering data about odor nuisance can significantly reduce the cost of odor studies, while giving citizens the knowledge and tools to address the odor pollution that affect them. WEFs MOP 25 also mentions citizen monitoring as part interactive community outreach programs that could collect data to represent real conditions in the community that also might help understanding the strength at which an odor becomes a nuisance. In classical psychometry, there is a certain consensus on the four basic factors that affect the sensitivity of individuals: experience, expectations, motivation and the degree of alertness of the receiver. Sensitivity of groups is also affected by these four parameters. In the case of people exposed to odor impact, there are however other factors that affect group sensitivity such as: the amount of population affected (city, town, scattered houses, etc.), the land-use where the receptors are located (industrial, rural, hospital, school, etc.), the housing uses (continuous, occasional, fortuitous, etc.), or even the type of environmental protection that the impacted area may have. Weighting receptor sensitivity may be assessed using traditional psychometric tools. Psychometry is a science that deals with theory and techniques to measure psychological perceptions. The contents of psychometry are usually built upon two blocks: Theory of surveys/questionnaires/tests and, scaling, methods to perform scales, rules. Key concepts in psychometry are validity and reliability. These two parameters can be measured statistically. Odor managers have a nice tool box when they want to assess odor impact by using traditional psychometry. The most common techniques used are interviews, surveys, odor diaries and analysis of records of complaints. However, there are many limitations of these psychometric approaches, being the main one that the odor timestamp record is not accurate and thus, there are more difficulties in assessing the reliability of the odor observations recorded. Advanced psychometry, uses citizen odor observations in real time to asses odor impact in a community. There several initiatives dealing with this new way of evaluating odor impact. The European Union Horizon 2020 Science with & for Society Call funded Distributed Network for Odour Sensing, Empowerment and Sustainability (D-NOSES) project aims to develop a methodology based on participatory strategies, collaboration of different stakeholders using an extreme citizen science approach. Building on action research and participatory design (Foth et al., 2006), the goal of the project is to support and guide a collaborative journey to tackle odor pollution with the active involvement of key stakeholders from the public sector, business, civil society, and academia. In the D-NOSES methodology (Balestrini et al, 2018; Arias et al., 2019), citizens are part of this process by framing odor issues in their affected areas. This is done through identifying local odor problems, collective data collection, collective analysis of the results and co-designing measures to tackle odor pollution. Data collected by citizens shows a real, local understanding of the problem, and reduces costs of odor pollution measurements at the same time. As part of the D-NOSES project, a pilot study has been conducted in Los Alamos, Chile (15,000 inhabitants). Modifications to the 20 year old WWTP were introduced in 2018, including a technology shift from SBR to Activated Sludge and scrubbers and biofilters for odor abatement. Still, the WWTP impacts three neighborhoods (Villa Caupolic¡n, Villa Esperanza and Kintupi Ruca), which are located in the dominant wind direction. The case study started in June 2019 with an odor annoyance assessment questionnaire as described in VDI 3883 part 1. The aim of the odor annoyance assessment was to have a clear, not biased, image of the affected areas, in order to have an improved focus of the citizen engagement strategy. Results indicate a plausible relation between odor annoyance values measured with the verbal and the thermometer scale. The latter ranges from 0 (not annoyed at all) to 10 (extremely annoyed). Arithmetic means for Villa Caupolic¡n (close to source) was 5.7. Kintupi Ruca averaged 3.4, while Villa Esperanza and Villa Caupolic¡n (distant to source) 1.7. Field inspections are carried out since December 2018 by trained assessors to determine the impact frequency of recognizable odors in terms of odor hours, using the grid method described in VDI 3940 part 1 (EN 16841). The assessment area covers the three neighborhoods with 17 assessment squares. No odor impact was observed for Villa Esperanza and distant to source zone at Villa Caupolic¡n. Close to the source zone at Villa Caupolic¡n and Kintupi Ruca largely have odor impact characteristics below the 10 % threshold value, but two assessment squares located nearby a pumping station exceed this threshold. Citizen data collection started at the end of November 2019 and was suspended in May 2020 due to the corona pandemic. In addition to random observations, a group of local residents were trained as panelists to realize twice a day a predefined 1.8 km track covering 17 of the 29 measurement points considered in the field inspections, reporting odor observation by using the OdourCollect app. The app enables to report types and sub-types of odors, intensity, hedonic tone, and comment on the duration of the odor episode and the potential source. Geographic coordinates and a timestamp are automatically recorded. Data analysis of the citizen monitoring comprises more nearly 3,000 individual observations. Therefore, new indicators are developed, adopting those proposed by traditional technical standards: Observations frequencies are calculated for each assessment zone, using the grid method evaluation described in VDI 3940 part 1 (EN 16841). Citizen had not been trained on VDI 3882 part 1 (odor intensity) nor on VDI 3882 part 2 (hedonic tone), but both characteristics can be reported with the OdourCollect app. The observed relation between hedonic tone and intensity can be described as linear functions. Finally, a weekly annoyance index is calculated for each assessment square and observation week using the equation given in VDI 3883 part 2. Therefore, the reported odor intensity is related to an annoyance category. The aim of this study is to identify drawbacks and potentials of combining different approaches in which citizens take an active role. It will also present advances in the development of a new standard based on the construction of collaborative odor maps through citizen science. The development of the standard is being promoted by the International Environmental Association of Odor Managers (AMIGO) and a handful of other groups and experts.