Associations between socioeconomic status and ultrafine particulate exposure in the school commute: An environmental inequality study for Toronto, Canada.

Ultrafine particulate matter (UFP) air pollution is unevenly distributed across urban environments. Disparities in routine activity patterns, such as the exposure risk we face at work or on the commute, can contribute to chronic exposure-related health outcomes that place excess burdening on vulnerable population groups. In Canada, there is disagreement in the literature on the nature of these exposure-related inequalities, and our understanding of disparities associated with specific activity patterns such as commuting is limited. In the context of UFP specific exposure, these relationships are almost entirely unexplored in the environmental inequality literature. Our study presents an exploratory analysis of UFP exposure patterns in Toronto, Canada. We examined UFP dosage disparities experienced by children during routine school commutes. We estimated single trip dosages that accounted for variation in ambient UFP concentration, route morphology (distance, slope) and their effect on inhalation rate and trip duration. We aggregated these values at the dissemination-area level and collected socioeconomic status descriptors from the 2016 census. Our OLS model showed significant spatial autocorrelation (MI = 0.59, p < 0.001), and we instead applied a spatial error model to account for spatial effects in our dataset. We identified significant associations related to median income (ß = -0.087, p < 0.05), government transfer dependence (ß = -0.107, p < 0.005), immigration status (ß = 0.119, p < 0.001), and education rates (ß = -0.059, p < 0.05). Our results diverged from other pollutants in Toronto-based literature and could indicate that UFPs exhibit unique patterns of inequality. Our findings suggest a need to further study UFP dosage from an environmental inequality perspective.

Geospatial datasets describing route geometry and ultrafine particulate matter dosage for children during shortest-distance and lowest-dosage school commutes in Toronto, Canada.

The data in this article provides route geometries and ultrafine particulate dosage information for a simulation of the home-to-school walking commute for children at 296,862 residential addresses in the city of Toronto, Canada. The datasets include dosage estimates that use a modelling approach that accounts for terrain, physiology and spatial variability in ambient UFP concentrations. The dataset provides simulated routes that describe both the shortest distance route, as well as the lowest UFP dosage route. Dosage and route information are provided in both polyline (route) and point (origin address) feature classes. Included in this article is a brief description of the simulation approach taken to generate the data. For discussion and complete description of the modelling approach, please refer to "Exposure to ultrafine particulate air pollution in the school commute: Examining low-dose route optimization with terrain-enforced dosage modelling" [1].

Exposure to ultrafine particulate air pollution in the school commute: Examining low-dose route optimization with terrain-enforced dosage modelling.

Exposure to ultrafine particulate air pollution (UFP) contributes to adverse health effects in sensitive population groups such as children. There is a need to explore UFP exposure in terms of respiratory dosage, which leverages the effect of activity-specific ventilation rates. Commute-related dosage, which describes the dosage that occurs during travel between fixed locations on a routine schedule (i.e. morning school commute), is often underrepresented in air pollution studies. School commutes commonly utilize active transportation modes, and modelling dosage during such commutes requires the development of an approach that captures the influence of travel mode and terrain-enforced ventilation rates. The concept of low-dosage routing is discussed as a solution to UFP dose mitigation; however, it requires an in-depth understanding of the factors that control how dosage is accumulated at different points in the commute. This paper presents a modelling workflow for examining UFP dosage while walking to school. We apply a GIS-based approach that simulates school commute routes for 296,862 homes in Toronto. We use a physical exertion-dependent dosage model that reflects broad-scale variability in physiology, travel velocity, travel gradient, and ambient UFP concentration to evaluate route-specific commute dosage. Our results reveal the patterns of within-route variation in dosage and demonstrate the effects high regional UFP concentration and accelerated physical exertion (i.e. where ventilation rate increases during uphill travel) on creating sections of greater UFP dosage within a route. We use the model to examine UFP dosage under shortest-distance and lowest-dosage routing solutions and find that 13.4% of homes had low-dosage alternative routes, while 86.6% had shortest-distances route that were already the lowest-dosage. Our findings were consistent with studies in the literature that implement a dosage modelling approach. This study highlights the importance of dosage models that account for the dynamic nature of walking speed, ventilation rate, terrain, and pollution concentration along a school commute.

Mapping the origins of Imperial Roman workers (1st-4th century CE) at Vagnari, Southern Italy, using 87 Sr/86 Sr and δ18 O variability.

OBJECTIVES: We obtained the oxygen and strontium isotope composition of teeth from Roman period (1st to 4th century CE) inhabitants buried in the Vagnari cemetery (Southern Italy), and present the first strontium isotope variation map of the Italian peninsula using previously published data sets and new strontium data. We test the hypothesis that the Vagnari population was predominantly composed of local individuals, instead of migrants originating from abroad. MATERIALS AND METHODS: We analyzed the oxygen (18 O/16 O) and strontium (87 Sr/86 Sr) isotope composition of 43 teeth. We also report the 87 Sr/86 Sr composition of an additional 13 molars, 87 Sr/86 Sr values from fauna (n = 10), and soil (n = 5) samples local to the area around Vagnari. The 87 Sr/86 Sr variation map of Italy uses 87 Sr/86 Sr values obtained from previously published data sources from across Italy (n = 199). RESULTS: Converted tooth carbonate (δ18 ODW ) and 87 Sr/86 Sr data indicate that the majority of individuals buried at Vagnari were local to the region. ArcGIS bounded Inverse Distance Weighting (IDW) interpolation of the pan-Italian 87 Sr/86 Sr data set approximates the expected 87 Sr/86 Sr range of Italy's geological substratum, producing the first strontium map of the Italian peninsula. DISCUSSION: Results suggest that only 7% of individuals buried at Vagnari were born elsewhere and migrated to Vagnari, while the remaining individuals were either local to Vagnari (58%), or from the southern Italian peninsula (34%). Our results are consistent with the suggestion that Roman Imperial lower-class populations in southern Italy sustained their numbers through local reproduction measures, and not through large-scale immigration from outside the Italian peninsula.