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The regularly reported associations between particulate matter (PM) exposure, and morbidity and mortality due to respiratory, cardiovascular, cancer, and metabolic diseases have led to the reduction in recommended outdoor PM10 and PM2.5 exposure limits. However, indoor PM10 and PM2.5 concentrations in subway systems in many cities are often higher than outdoor concentrations. The effects of these exposures on subway workers and passengers are not well known, mainly because of the challenges in exposure assessment and the lack of longitudinal studies combining comprehensive exposure and health surveillance. To fulfill this gap, we made an inventory of the PM measurement campaigns conducted in the Parisian subway since 2004. We identified 5856 PM2.5 and 18,148 PM10 results from both personal and stationary air sample measurements that we centralized in a database along with contextual information of each measurement. This database has extensive coverage of the subway network and will enable descriptive and analytical studies of indoor PM exposure in the Parisian subway and its potential effects on human health.

Subway particulate toxicity results from in vitro and in vivo studies diverge and call for applied human research on outcomes from chronic exposures and potential exposure biomarkers. We aimed to (1) quantify airborne particulate matter (PM) concentrations (mass and number) and metal concentrations in exhaled breath condensate (EBC), urine, and PM; (2) investigate their associations (EBC vs. PM vs. urine); and (3) assess the relevance of EBC in biomonitoring. Nine subway workers in three jobs: station agents, locomotive operators and security guards were monitored during their 6-h shifts over two consecutive weeks. Six-hour weighed average mass concentrations expressed as PM10, PM2.5 and their metal concentrations were determined. Urine and EBC samples were collected pre- and post-shift. Ultrafine particle (UFP) number concentrations were quantified in PM and EBC samples. Metal concentrations in urine and EBC were standardized by creatinine and EBC volume, respectively, and log-transformed. Associations were investigated using Pearson correlation and linear mixed regression models, with participant's ID as random effect. PM concentrations were below occupational exposure limits (OEL) and varied significantly between jobs. Locomotive operators had the highest exposure (189 and 137 μg/m 3 for PM10 and PM2.5, respectively), while station agents had the highest UFP exposure (1.97 × 10 4 particles/cm 3 ). Five metals (Al, Fe, Zn, Cu, and Mn) in PM2.5 and three (Al, Fe, and Zn) in PM10 were above the limit of quantification (LOQ). Fe, Cu, Al and Zn were the most abundant by mass fraction in PM. In EBC, the metal concentrations in decreasing order were: Zn > Cu > Ni > Ba > Mn. Security guards had the highest EBC metal concentrations, and in particular Zn and Cu. Urinary metal concentrations in decreasing order were: Si > Zn > Mo > Ti > Cu > Ba ≈ Ni > Co. All urinary metal concentrations from the subway workers were similar to concentrations found in the general population. A statistically significant relationship was found for ultrafine particle number concentrations in PM and in EBC. Zn and Cu concentrations in post-shift EBC were associated with Zn and Cu concentrations in PM10 and with post-shift urinary Zn and Cu concentrations. Therefore, EBC appears a relevant matrix for assessing exposure to UFP in human biomonitoring when inhalation is a primary route of exposure. We found different temporal variation patterns between particle and metal exposures in three matrices (PM, urine, EBC) quantified daily over two full weeks in subway workers. These patterns might be related to metal oxidation, particulates' solubility and size as well as their lung absorption capabilities, which need to be further explored in toxicological research. Further research should also focus on understanding possible influences of low chronic exposures to subway particulates on health in larger cohorts.

Background Air pollution in subway environments is a growing concern as it often exceeds WHO recommendations for indoor air quality. Ultrafine particles (UFP), for which there is still no regulation nor a standardized exposure monitoring method, are the strongest contributor to this pollution when the number concentration is used as exposure metric. Objectives We aimed to assess the real-time UFP number concentration in the personal breathing zone (PBZ) of three types of underground Parisian subway professionals and analyze it using a novel Bayesian spline approach. Consecutively, we investigated the effect of job, week day, subway station, worker location, and some further events on UFP number concentrations. Methods The data collection procedure originated from a longitudinal study and lasted for a total duration of 6 weeks (from October 7 to November 15, 2019, i.e. two weeks per type of subway professionals). Time-series were built from the real-time particle number concentration (PNC) measured in the PBZ of professionals during their work-shifts. Complementarily, contextual information expressed as Station, Environment, and Event variables were extracted from activity logbooks completed for every work-shift. A Bayesian spline approach was applied to model the PNC within a Bayesian framework as a function of the mentioned contextual information. Results Overall, the Bayesian spline method suited a real-time personal PNC data modeling approach. The model enabled estimating the differences in UFP exposure between subway professionals, stations, and various locations. Our results suggest a higher PNC closer to the subway tracks, with the highest PNC on subway station platforms. Studied event and week day variables had a lesser influence. Conclusion It was shown that the Bayesian spline method is suitable to investigate individual exposure to UFP in underground subway settings. This method is informative for better documenting the magnitude and variability of UFP exposure, and for understanding the determinants in view of further regulation and control of this exposure.

Contexte La prevention des effets respiratoires lies aux expositions professionnelles a des aerocontaminants est un enjeu important pour les medecins du travail. Entre 20 et 30 % des bronchites chroniques obstructives (BPCO) sont liees a des expositions professionnelles, comme les particules fines ou ultrafines, qui peuvent induire un stress oxydant. Des biomarqueurs du stress oxydant pourraient etre proposes pour le depistage precoce des effets respiratoires, notamment de la BPCO, a condition d’etre valides et mesurables dans des prelevements biologiques peu invasifs. Methodes Une revue de litterature sur les biomarqueurs pertinents pour la surveillance de travailleurs a ete realisee, puis un projet de recherche collaborative entre l’IST et l’UPST-RATP a ete propose pour selectionner et valider les biomarqueurs du stress oxydatif non invasifs. Resultats Le projet Respiratory disease Occupational Biomonitoring Collaborative Project (ROBoCop) est bâti dans le cadre du consortium europeen CliniMark (Action EU-COST CA16113) et soutenu par le Fonds national suisse de la recherche scientifique. Il comporte trois parties : 1. Standardisation du recueil des echantillons biologiques (condensat d’air exhale, urine) et des methodes d’analyses des biomarqueurs retenus (8-isoprostane, malondialdehyde, NO2−, NO3−, ions formates et 8-hydroxy-2’deoxyguanosine) et validation de l’analyseur OPEA (oxidative potential in the exhaled air) developpe par l’IST (Brevet EU et Etats-Unis). 2. Etude pilote a la RATP pour definir le protocole d’echantillonnage standardise et evaluer la faisabilite de la mesure des biomarqueurs selectionnes chez les travailleurs exposes aux particules fines et ultrafines. 3. Etude de terrain sur 300 travailleurs volontaires de la RATP, selectionnes par randomisation stratifiee (âge, tabac, exposition professionnelle) sur les 45 000 travailleurs suivis par les 34 medecins de l’entreprise. Les donnees issues des consultations medicales (examen clinique + spirometrie) et de l’analyse des echantillons biologiques seront analysees afin de rechercher une correlation entre les biomarqueurs etudies et la survenue d’un syndrome obstructif. Conclusion Ce projet permettra d’elaborer des protocoles standardises et des recommandations de bonne pratique pour l’usage des biomarqueurs du stress oxydatif a partir des prelevements non invasifs, dans un service de sante au travail. Il permettra de valider l’utilisation de biomarqueurs pour le depistage de la BPCO chez les travailleurs exposes, voire pour le depistage en population generale, ou pour le suivi medical de patients atteints par cette pathologie.