Environmental assessments on schools located on or near former industrial facilities: Feedback on attenuation factors for the prediction of indoor air quality

Relating mercury occurrence in soil gases at establishments hosting children to historical mercury-using activities in Paris, France

Volatile pollutants from former industrial sites can degrade the buildings' indoor air quality that were built after the industrial activities. Since 2010, environmental assessments have been conducted in French establishments hosting sensitive populations identified as being on or near potentially contaminated former industrial sites. These projects are based on historical studies traditionally carried out as part of managing contaminated sites, to determine which substances should be analyzed. They pinpoint former activities likely to have stored or used pollutants. We show that the historical information collected is not effective in targeting sites with increased probability of mercury being present in soil gases. Environmental history has demonstrated the existence of large-scale artisanal contamination, both prior to and concomitant with the industrial era. Classic historical studies would not take into account artisanal activities, which are less documented than industrial activities. We carried out additional research for three schools located in three different Parisian districts. Although information on activities which could have emitted mercury was relatively imprecise (in terms of location, type and duration of activities) and uncertainties exist about the completeness of the archival documents available, our investigations identified several mercury-using activities that had not been identified during the classic historical study. However, we have shown that the number of activities identified does not provide information on how mercury has affected soil gas. Consequently, although a more extensive historical research improves knowledge about the presence of potential mercury-using activities, our study shows that a systematic analysis of mercury as part of the assessment of establishments hosting sensitive populations remains relevant. This approach should be applied to other cities around the world.

Vapor Intrusion Investigations and Decision-Making: A Critical Review

At sites impacted by volatile organic compounds (VOCs), vapor intrusion (VI) is the pathway with the greatest potential to result in actual human exposure. Since sites with VI were first widely publicized in late 1990s, the scientific understanding of VI has evolved considerably. The VI conceptual model has been extended beyond relatively simple scenarios to include nuances, such as biological and hydrogeological factors that may limit the potential for VI and alternative pathways, such as preferential pathways and direct building contact/infiltration that may enhance VI in some cases. Regulatory guidance documents typically recommend initial concentration- or distance-based screening to evaluate whether VI may be a concern, followed by a multiple-lines-of-evidence (MLE) investigation approach for sites that do not screen out. These recommendations for detailed evaluation of VI currently focus on monitoring of VOC concentrations in groundwater, soil gas, and indoor air and can be supplemented by other lines of evidence. In this Critical Review, we summarize key elements important to VI site characterization, provide the status and current understanding, and highlight data interpretation challenges, as well as innovative tools developed to help overcome the challenges. Although there have been significant advances in the understanding of VI in the past 20 years, limitations and knowledge gaps in screening, investigation methods, and modeling approaches still exist. Potential areas for further research include improved initial screening methods that account for the site-specific role of barriers, improved understanding of preferential pathways, and systematic study of buildings and infrastructure other than single-family residences.

Evaluation of volatile organic compounds coupled to seasonality effects in indoor air from a commercial office in Madrid (Spain) applying chemometric techniques

Volatile organic compounds (VOCs) concentrations depend on several sources and factors, such as temperature, ventilation, and humidity. Sources can be external atmospheric pollution or indoor release from furniture, coatings or occupants. In this context, this study focused on quantification of VOCs present in a confined atmosphere in a commercial office in downtown Madrid, Spain. The influence of seasonal changes in VOCs concentrations was evaluated using chemometric approaches. Indoor air was systematically monitored for one year using stainless steel tubes filled with Tenax® TA. Sampling was conducted one week a month, for three days during that week (Monday, Wednesday and Friday) for 60 min, every 2 h, totaling 24 h, using an autosampler carousel. The analyses were performed using thermal desorption, and compounds were analyzed by a gas chromatograph coupled with a mass spectrometer. The correlation between these compounds and their concentrations, climatic variations, seasons, among others, were explained by multivariate statistics. Considering the current legislation in Spain, only benzene was present above the maximum permissible concentration (threshold value < 1 μg/m³) from all analyzed compounds. The results indicate that concentrations are related to significant environmental changes, such as ventilation, the number of occupants in the office and types of activity undertaken in the environment. The chemometric analyses allowed the identification of structure analyses correlations between multiple variables for the one-year study. These results underscore the importance of indoor atmosphere studies and chronic exposure to these contaminants.