The spatial and temporal variability of nitrogen dioxide (NO2) concentrations and their relationships with meteorology was evaluated in the Toronto–Hamilton urban airshed. NO2 concentrations were highest in the early morning and late evening. Mean concentrations were highest in winter, although individual one‐hour NO2 concentrations were found to be highest in summer. Wind direction was the strongest control on hourly NO2 concentration, and temperature and wind speed also had an effect. Our analysis of NO2 concentration variation by wind direction showed that areas downwind of major highways, urban centres and industry were exposed to higher pollutant concentrations. Seasonal patterns of NO2 concentration displayed significant spatial heterogeneity, in particular, in Toronto. Onshore winds sheltered coastal inhabitants from the full extent of NO2 exposure they would otherwise experience. Seasonal variations in meteorology and emissions mean that the degree of spatial variability in NO2 concentrations changes from season to season. This study will help to improve existing land‐use regression‐based NO2 prediction models by incorporating meteorological controls on NO2 distributions for health effect studies.
The present experiment served as an initial empirical investigation of the spatial-verbal processing model of Dansereau and colleagues. The model was developed as a framework for elucidating the processes associated with the acquisition of information from spatial text displays (e.g., knowledge maps). The assumptions of the model lead to the contention that main ideas (processed mainly through spatial channels) act to cross-cue details (processed mainly through verbal channels). Moreover, this main idea-detail relationship can be expected to differ as a function of the temporal nature of acquisition (i.e., initial comprehension, encoding/storage, and recall/utilization). Participants in the present experiment were divided into two experimental groups, map and text. Both groups studied a passage of information over the autonomic nervous system and completed recall tests after a 5-min. overview, after studying for 30 min., and two days after the completion of studying. Those in the map group studied the information in the form of knowledge maps, while those in the text group studied traditional text. Recall results indicated that retention of details did not decay from initial to delayed recall, while the retention of main ideas did. Further, the main idea-detail relationship was mediated by the temporal nature of recall and experimental group. Main ideas and details were strongly related initially but not on subsequent recall for the map group, while just the opposite was the case for the text group.
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