SEARCH · Search PubMed

Results for “Cities”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 793 records · Page 44Linked to original sources

PubMed2004

The city as a context for scientific activity: creating the Mediziner-Viertel in fin-de-siècle Vienna.

At the turn of the 19th century, a surprisingly dense network of academic institutes and medical facilities developed on the margins of Ringstrasse, the impressive boulevard that surrounded the old city of Vienna. Enmeshed, socially and culturally in the life of the city, that area known as the Mediziner-Viertel grew out of the needs of natural scientists and physicians as much as it was shaped by the liberal ideology, feminists' petitions for women's acceptance to university studies, Vienna's intellectuals and Kaffeehaus culture. Recovering the city behind the structure of modern academic institutes tells us a good deal about the context in which intellectual work was developed and its impact on the production of scientific knowledge.

Academies and Institutes↗

PubMed2004

Relationship between air pollution and daily mortality in a subtropical city: Taipei, Taiwan.

Air pollution has been associated with daily mortality in numerous studies over the past decade. However most of these studies were conducted in the United States and Europe with relatively few done in Asia. In the current study, the association between ambient air pollution and daily mortality in Taipei, Taiwan's largest city which has a subtropical climate was undertaken, for the period 1994-1998 using a case-crossover analysis. This design is an alternative to Poisson time series regression for studying the short-term adverse health effects of air pollution. The air pollutants examined included particulate matter (PM(10)), sulfur dioxide (SO(2)), ozone (O(3)), nitrogen dioxide (NO(2)), and carbon monoxide (CO). The largest observed effect, which was without statistical significance, was seen for NO(2) and CO levels on deaths due to respiratory diseases (ORs=1.013 and 1.014, respectively). The well established link between air pollution levels and daily mortality may not be as strong in cities in subtropical areas, although other factors such as differences in pollutant mix or the underlying health of the population may explain the lack of a strong association in this study. Further studies of this type in cities with varying climates and cultures are needed.

Air Pollution↗

PubMed2005

The relationship between extreme heat and ambulance response calls for the city of Toronto, Ontario, Canada.

Concern over the impact of extreme heat upon human health has increased in recent years. Though much research has evaluated the relationships between the two, few studies have attempted to quantify this vulnerability on a sub-metropolitan area level. Using a Geographic Information System (GIS), ambulance calls for a 4-year period from 1999 to 2002 was analyzed in relation to extreme heat for the city of Toronto, Ontario, Canada. Ambulance response calls were plotted on a map to understand the spatial variability of where calls significantly increase above normal levels during oppressively hot days. Census data were used to identify the demographic characteristics of the population within these areas. Statistical tests were also used to assess the degree of correlation among different meteorological variables and the ambulance call data. Over the 4-year period, the average number of ambulance calls increases by 10 percent over normal levels on those days considered oppressively hot. A change in the spatial pattern of calls also occurs on such days. The urban core, with the greatest density of calls, experiences the greatest absolute percentage increase in calls from normal on oppressive days. However, it is some areas of the city located along the shore of Lake Ontario, where a high majority of the population goes to cool down, that demonstrate the greatest percentage increase in calls. Other areas of the city exhibiting an increase in calls are located within industrial and recreational areas.

Ambulances↗

PubMed2024

Antimicrobial resistance landscape in a metropolitan city context using open drain wastewater-based metagenomic analysis.

One Health concept recognizes the inextricable interactions of diverse ecosystems and their subsequent effect on human, animal and plant health. Antimicrobial resistance (AMR) is a major One Health concern and is predicted to cause catastrophes if appropriate measures are not implemented. To understand the AMR landscape in a south Indian metropolitan city, metagenomic analysis of open drains was performed. The data suggests that in January 2022, macrolide class of antibiotics contributed the highest resistance of 40.1% in the city, followed by aminoglycoside- 24.4%, tetracycline- 11.3% and lincosamide- 6.7%. The 'mutations in the 23S rRNA gene conferring resistance to macrolide antibiotics' were the major contributor of resistance with a prevalence of 39.7%, followed by '16s rRNA with mutation conferring resistance to aminoglycoside antibiotics'- 22.2%, '16S rRNA with mutation conferring resistance to tetracycline derivatives'- 9.2%, and '23S rRNA with mutation conferring resistance to lincosamide antibiotics'- 6.7%. The most prevalent antimicrobial resistance gene (ARG) 'mutations in the 23S rRNA gene conferring resistance to macrolide antibiotics' was present in multiple pathogens including Escherichia coli, Campylobacter jejuni, Acinetobacter baumannii, Streptococcus pneumoniae, Pseudomonas aeruginosa, Neisseria gonorrhoeae, Klebsiella pneumoniae and Helicobacter pylori. Most of the geographical locations in the city showed a similar landscape for AMR. Considering human mobility and anthropogenic activities, such an AMR landscape could be common across other regions too. The data indicates that pathogens are evolving and acquiring antibiotic resistance genes to evade antibiotics of multiple major drug classes in diverse hosts. The outcomes of the study are relevant not only in understanding the resistance landscape at a broader level but are also important for identifying the resistant drug classes, the mechanisms of gaining resistance and for developing new drugs that target specific pathways. This kind of surveillance protocol can be extended to regions in other developing countries to assess and combat the problem of antimicrobial resistance.

Cities↗

PubMed2006

Fat-related dietary behaviors of adult Puerto Ricans, with and without diabetes, in New York City.

OBJECTIVE: To assess the fat-related dietary behaviors of adult Puerto Ricans with and without diagnosed diabetes, living in New York City. DESIGN: A random-digit-dialing telephone survey was conducted following Behavioral Risk Factor Surveillance System procedures. Dietary behavior was assessed using a brief Fat-Related Diet Habits Questionnaire, in which higher scores indicated higher fat intake. SUBJECTS/SETTING: A total of 1,304 adult Puerto Ricans living in New York City were interviewed. Diabetes status was assessed using standard Behavioral Risk Factor Surveillance System questions. STATISTICAL ANALYSES PERFORMED: Weighted analyses using SUDAAN software for complex surveys were done, and t tests were used to assess differences in mean fat-related dietary score by sociodemographic and health characteristics. Age-adjusted least-squared means were used to compare scores between those with and without diabetes. Linear regression was used to model characteristics associated with fat-related dietary score. RESULTS: Fat-related dietary score was lower among those with diabetes and varied by population and health characteristics. Age-adjusted scores were significantly lower for those with diabetes who were younger, less educated, obese, or physically active. In the regression model, family history, weight, and exercise interacted with diabetes status. Those with diabetes were significantly more likely to modify meat consumption practices (eg, remove skin or trim fat) to reduce fat compared with those without diabetes. CONCLUSIONS: New York City Puerto Ricans with diabetes are somewhat more likely to engage in behaviors to reduce fat compared with those without diabetes. Targeted, culturally sensitive nutrition education and counseling emphasizing lower-fat food choices and other fat-reducing behaviors can help reduce risk and control diabetes. Education messages should be tailored to the individual's diabetes status and other health and sociodemographic characteristics.

Adolescent↗

PubMed2004

Use of a state-wide administrative database in assessing a regional trauma system: the New York City experience.

BACKGROUND: A successful regional trauma care system should concentrate severely injured patients within trauma centers, and should improve severity-adjusted outcomes. We compared injured patients' outcomes in New York City's level 1 trauma centers and nontrauma centers. STUDY DESIGN: We analyzed 1998-2000 New York Statewide Planning and Cooperative Research System (SPARCS) data for 103,725 adult discharges from 70 New York City hospitals (15 level I trauma centers), using ICD-9CM codes 800-950. Their 227 DRG's were aggregated into 7 clinical injury classes. A severity index was extracted from each refined DRG, and deaths, age, and gender were analyzed. Regression analysis predicted death from age, gender, severity index, and trauma center discharge, with separate analyses of the three largest clinical classes, and estimated excess mortality because of trauma center discharge. RESULTS: Level 1 trauma centers discharged 48.2% of injured patients, with higher mean annual discharges per hospital (1,046 discharges per TC vs. 437 per NTC, p < 0.001). Trauma centers discharged more than half the central nervous system, general/gastrointestinal, cardiothoracic, and vascular injuries. Trauma center patients were 12.5 years younger than NTC patients (p < 0.0005), and were disproportionately men (64.7% TC vs. 47.2% NTC, p < 0.0005). For the entire patient cohort, and for central nervous system, orthopaedic and general/gastrointestinal injuries, severity, age, and gender adjusted mortality risk was significantly greater at trauma centers than nontrauma centers. CONCLUSIONS: New York City's trauma system concentrates injured patients in trauma centers on the basis of injury class rather than severity, but does not produce improved adjusted mortality outcomes for injured patients.

Adult↗

PubMed2006

An inexact two-stage mixed integer linear programming method for solid waste management in the City of Regina.

In this study, an interval-parameter two-stage mixed integer linear programming (ITMILP) model is developed for supporting long-term planning of waste management activities in the City of Regina. In the ITMILP, both two-stage stochastic programming and interval linear programming are introduced into a general mixed integer linear programming framework. Uncertainties expressed as not only probability density functions but also discrete intervals can be reflected. The model can help tackle the dynamic, interactive and uncertain characteristics of the solid waste management system in the City, and can address issues concerning plans for cost-effective waste diversion and landfill prolongation. Three scenarios are considered based on different waste management policies. The results indicate that reasonable solutions have been generated. They are valuable for supporting the adjustment or justification of the existing waste flow allocation patterns, the long-term capacity planning of the City's waste management system, and the formulation of local policies and regulations regarding waste generation and management.

Canada↗

PubMed2026

Biomass burning contributions to Mexico City's atmospheric CO2 estimated using a multi-isotope approach.

Fossil fuel combustion dominates anthropogenic emissions worldwide; however, special attention should be addressed to biomass burning, since it is an increasingly important contributor under warmer, drier fire-weather conditions exacerbated by climate change. These emissions could impact the atmospheric composition of heavily urbanized environments. To assess the influence of biomass burning, along with fossil fuels combustion and soil and plant respiration on Mexico City's atmospheric composition, we conducted a year-long (December 2023-December 2024) isotopic monitoring of atmospheric CO2, combining radiocarbon (Δ14C), CO2 stable isotopes (δ13C, δ18O), and CO/CO2 ratios. Once defined the isotopic signatures and the characteristic CO/CO2 that describe the sources, we performed Monte Carlo simulations under two tracer modalities (Δ14C + CO/CO2 and Δ14C + CO2 stable isotopes) for source apportionment. Results show that during the dry season, particularly in March-April, atmospheric Δ14C values approached and overlapped background levels despite Mexico City's fossil-fuel dominance, indicating enhanced non-fossil inputs. Moreover, backward HYSPLIT trajectories supported that these elevated Δ14C values coincided with regional wildfire activity. Monte Carlo results attributed up to ∼34 %-60 % of local CO2 to biomass burning in April, followed by March with contributions of ∼31 %-49 %. Since these biomass burning figures contrast with the official emissions inventory of Mexico City metropolitan area, which assigns <1 % of total CO2 emissions to biomass burning, this study could exhibit the emissions inventory underestimation of this source, and thus, the need to reassess and incorporate top-down isotopic constraints in fire-affected urban regions.

Mexico↗

PubMed2005

Metals in soils of children's urban environments in the small northern European city of Uppsala.

Metals occur naturally in soil, but contents are generally increased in the urban environment due to anthropogenic activities. The presence of elevated metals in soils of the urban environment has been recognized as an important source of metal intake in children and is linked to elevated metal levels in children's blood. Several metals have undesirable health effects, especially on children due to their still developing nervous system and small body volumes. Playgrounds are where urban children spend most of their time outdoors and are also where children most frequently come in contact with soil. Elevated contents of metals in playgrounds are therefore of great concern for children's wellbeing. This study investigates the soil metal content of 25 playgrounds located in different land use areas in urban Uppsala, Sweden's fourth largest city. Uppsala covers an area of approximately 100 km2 and has a population of 136,000. The soil samples were analysed for 12 metals (Al, As, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, W, Zn) using aqua regia. Median metal contents were found to be 1.8, 3.4, 0.21, 32, 25, 2.5, 0.14, 494, 19, 26, 0.35 and 84 mg kg(-1) soil for each of the above metals, respectively. The median clay content was around 20% while the organic matter content was measured by loss on ignition at a median of 8%. The land use areas included industrial land, the city center, road verges, natural land and former industrial land. The results showed that land use did not have the expected large influence on the total metal contents of the soils tested. The clay content together with the age of the site proved to be a more important factor. Sites with elevated clay contents had in general elevated metal contents, which were explained by the relatively high adsorption capacity of clay particles. The soils at sites where land use had not been altered since the 1800s had increased metal contents compared to playgrounds constructed in the late 1900s. The immobility of metals once they had entered the soil system was the reason for increased metal content in soils of old playgrounds. It was concluded that in cities with few internal pollution sources, the soil characteristics of the site and the time the soil has been on-site to accumulate metal residues become important factors in determining the soil metal content.

Arsenic↗

PubMed2006

Mercury in the topsoil and dust of Beijing City.

Research on mercury concentration in the dust and topsoil of Beijing City reveals the following conclusions: mercury concentration in Beijing topsoil and dust is middle compared to other mercury concentration studies and varies greatly in different sampling spots. Mercury concentration in the topsoil is between 0.019mg.kg(-1) and 0.966mg.kg(-1), it is about 2.11 times and 12.08 times of mercury concentration background in Beijing soil respectively. Mercury concentration in Beijing dust has a range of 0.053 to 1.378mg.kg(-1); the maximum mercury concentration in the Beijing dust in 2003 is about 2.2 times of that in 1992. These results show that mercury pollution in Beijing topsoil and dust are serious, and mercury tends to enrich in the dust compared to the adjacent topsoil. Mercury in topsoil and dust of Beijing City has obvious regional differentiation characteristics, which is highest in the center of Beijing City and lower away from the center to the suburbs. In detail, mercury concentration in the topsoil samples and dust samples are highest in Dongsi area and lowest in the blank spot. Mercury in Beijing's topsoil belonging to point pollution is mainly from local area; mercury in the dust belongs to non-point source pollution because the source of mercury in the dust is very complex. Natural factors and anthropological factors have certain effect on mercury concentration in the topsoil and dust, and anthropological factors have more effect. The results are very important to protect and enhance our environmental quality.

Air Pollutants↗

PubMed2006

Lead concentrations and isotope ratios in street dust in major cities in Greece in relation to the use of lead in petrol.

Until recently, the most important source of environmental lead pollution in cities was thought to come from the combustion of leaded petrol. A simple way to monitor the extent of this phenomenon, used in a number of studies in the past, has been to measure lead levels in street dust. Nowadays, it would be expected that lead concentrations in urban dust would have decreased from earlier values, following the progressive reduction of lead in petrol over the past few years, and this hypothesis has recently been confirmed in Manchester, UK. The object of the present work is to determine levels of lead pollution in cities in Greece on 1997 and, if possible, to discover whether similar reductions in lead concentrations have occurred there also. Surveys have been conducted in Thessaloniki, Athens and Piraeus. Samples of roadside dust were collected from streets (categorised by traffic density), national gardens and school playgrounds, and lead was extracted by digestion with concentrated nitric acid. Lead concentrations were determined by graphite furnace atomic absorption spectrometry and lead isotope ratios measured by inductively coupled plasma mass spectrometry. Results for Thessaloniki showed that mean lead concentrations in all categories of location are similar to present levels in Manchester. Further, lead concentrations in dust in the busiest streets in Thessaloniki have fallen by about 55% since a previous study 17 years ago. In Athens and Piraeus, the lead levels in street dust are much higher and significant differences were observed between the various types of street. In particular, it was observed that lead levels in school playgrounds in these two cities were much higher than in similar locations in Thessaloniki and Manchester, with a possible hazard to children. Isotope ratio measurements showed that Thessaloniki's lead is isotopically distinct from that found in Athens and Piraeus, which presumably reflects differences in sources of supply.

Cities↗

PubMed2006

Characterization of PM(2.5) in the ambient air of Shanghai City by analyzing individual particles.

PM(2.5) samples were collected simultaneously at three representative areas (central city, industrial area and clean air suburban) of Shanghai City. Their morphologies and elemental compositions were determined by scanning electron microscopy coupled with energy analysis (SEM-EDX). The particles were classified into four groups based on morphology and elemental composition. Soot aggregates and spherical fly ash particles were the two dominant types and they were identified as originating from automobile exhaust, metallurgical industry and coal combustion. The size distribution of the particles showed that most had diameters in the range of 0.2-1.4 microm. Individual particles were measured by synchrotron radiation micro-beam X-ray fluorescence (micro-SXRF) and the micro-SXRF spectra were obtained. Pattern recognition techniques, which took the micro-SXRF spectrum of a single aerosol particle as its fingerprint, were used to identify the origins of the particles. Seven source types were identified. They were: metallurgical industry, vehicle exhaust, soil dust, coal combustion, diesel exhaust, oil combustion and motorcycle exhaust. Metallurgical industry, automobile exhaust, and coal combustion were recognized to be the main pollution sources of PM(2.5) in the air of Shanghai City.

Air Pollutants↗

PubMed2006

Mercury in urban soils: a comparison of local spatial variability in six European cities.

The objective of this study was to quantify and assess for the first time the variability of total mercury in urban soils at a European level, using a systematic sampling strategy and a common methodology. We report results from a comparison between soil samples from Aveiro (Portugal), Glasgow (Scotland), Ljubljana (Slovenia), Sevilla (Spain), Torino (Italy) and Uppsala (Sweden). At least 25 sampling points (in about 4-5 ha) from a park in each city were sampled at two depths (0-10 and 10-20 cm). Total mercury was determined by pyrolysis atomic absorption spectrometry with gold amalgamation. The quality of results was monitored using certified reference materials (BCR 142R and BCR 141R). Measured total mercury contents varied from 0.015 to 6.3 mg kg(-1). The lowest median values were found in Aveiro, for both surface (0-10 cm) and sub-surface (10-20 cm) samples (0.055 and 0.054 mg kg(-1), respectively). The highest median mercury contents in soil samples were found in samples from Glasgow (1.2 and 1.3 mg kg(-1), for surface and sub-surface samples, respectively). High variability of mercury concentrations was observed, both within each park and between cities. This variability reflecting contributions from natural background, previous anthropogenic activities and differences in the ages of cities and land use, local environmental conditions as well as the influence of their location within the urban area. Short-range variability of mercury concentrations was found to be up to an order of magnitude over the distance of only a few 10 m.

Cities↗

PubMed2006

The influence of a city on element contents of a terrestrial moss (Hylocomium splendens).

Forty terrestrial moss (Hylocomium splendens) samples were collected along a 120-km-long south-north transect running through Norway's largest city Oslo. Concentrations of 29 chemical elements (Ag, Al, Au, Ba, Bi, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, La, Mg, Mn, Mo, Na, Ni, P, Pb, Pt, S, Sb, Sr, Th, Ti, and Zn) and values for loss on ignition (475 degrees C) are reported. Silver (Ag), Al, Au, Bi, Cd, Co, Cr, Cu, Fe, Mo, Ni, Pb, Pt, Sb, Th, Ti, and Zn all show a characteristic Oslo peak when element concentrations are plotted against location of the sample site along the transect. Gold (Au) and Pt show the greatest relative enrichment of all elements in the city (ca. 10x "background"). Titanium (Ti), which is related to local minerogenic dust rather than anthropogenic emissions, shows a significant peak in Oslo. Loss on ignition, a measure of the amount of organic material in a sample, shows a negative peak in Oslo and at sites close to a known dust source. Input of fine dust thus appears to dominate many of the observed element concentrations in moss. The concentrations of Na are clearly influenced by the input of marine aerosols and show decreasing concentrations from south (near Oslo Fjord) to north (inland). The major plant nutrients Ca, K, Mg, P and S, as well as Hg, are the few elements displaying no spatial dependency along the transect. Element concentrations reach background variation levels at a distance of 20-40 km from the city centre.

Adsorption↗

PubMed2006

Composition of source-sorted municipal organic waste collected in Danish cities.

Source-sorted municipal organic waste from different dwelling types in five Danish cities was sampled during one year. The samples were from permanent, full-scale systems or temporary, experimental systems for collection of source-sorted municipal organic waste. Pre-treatment of the organic waste prior to biological treatment was used in all cities to remove foreign objects and provide size reduction. All sampling was performed after pre-treatment in order to obtain more homogeneous and representative samples. The sampling included both the pre-treated waste and the reject from the pre-treatment allowing for estimation of the composition of the original waste. A total of 40 waste samples were chemically characterised with respect to 15 parameters. The waste generally consisted of around 88% VS of which an average of 80% was easily degradable. The average content of N, P and K in the dry matter of the organic waste was 2.5%, 0.4% and 0.9%, respectively. A general analysis of variance was applied to show the influence of the collection system, dwelling type and annual season on the waste composition. The content of plastic and crude fibres in the waste differed the most among the samples, probably due to use of different bag types (plastic and paper) in the different collection systems. Variations in the ash content and the calorific value might be explained by differences in the sorting instructions (whether soil and cat litter are allowed in the organic fraction). Significant seasonal variations were seen for ash, S and Cl. Dwelling type showed no statistically significant influence on any waste components. A test for uniform distribution of the p-values from the analysis of variance (Kolmogorov-Smirnov test) showed that the overall composition of the collected waste was strongly affected by the collection system (city) and season, while dwelling type had no significant influence.

Carbohydrates↗

PubMed2006

Modeling of urban solid waste management system: the case of Dhaka city.

This paper presents a system dynamics computer model to predict solid waste generation, collection capacity and electricity generation from solid waste and to assess the needs for waste management of the urban city of Dhaka, Bangladesh. Simulated results show that solid waste generation, collection capacity and electricity generation potential from solid waste increase with time. Population, uncleared waste, untreated waste, composite index and public concern are projected to increase with time for Dhaka city. Simulated results also show that increasing the budget for collection capacity alone does not improve environmental quality; rather an increased budget is required for both collection and treatment of solid wastes of Dhaka city. Finally, this model can be used as a computer laboratory for urban solid waste management (USWM) policy analysis.

Bangladesh↗

PubMed1998

Association of being overweight with greater asthma symptoms in inner city black and Hispanic children.

OBJECTIVE: To determine whether the weight status of inner city black and Hispanic children with asthma differs from that of their peers and to assess whether overweight asthmatic children experience greater asthma symptoms. STUDY DESIGN: A cross-sectional study in an ambulatory chest clinic of an inner city medical center. METHODS: We studied black and Hispanic children aged 2 to 18 years (n = 209) with the single diagnosis of asthma. The peer control subjects consisted of a sample of black and Hispanic children aged 6 to 13 years (n = 1017), enrolled in the New York City schools. Asthma symptoms, the number of asthma medications prescribed, and peak expiratory flow rate (PEFR) measurements were used to classify asthma severity and relate to body mass index (BMI). Bivariate categorical analysis and chi 2 tests were performed to examine the relationship between high BMI and the individual measures of asthma severity. RESULTS: The prevalence of overweight was significantly higher in children with moderate to severe asthma than in their peers. The risk of overweight based on a BMI in the 85th percentile or greater was significantly associated with the following measures of asthma severity: (1) the number of school days missed per year; (2) a PEFR less than or equal to 60% of the predicted PEFR; and (3) the number of asthma medications prescribed. CONCLUSIONS: The prevalence of overweight was significantly higher in children with moderate to severe asthma than in their peers, and being overweight was associated with significantly more severe asthma symptoms. Further studies in overweight asthmatic children are needed, including the effect of weight loss on lung function and other markers of asthma severity.

Adolescent↗

PubMed2002

Chemical composition of PM2.5 and PM10 in Mexico City during winter 1997.

PM2.5 and PM10 were measured over 24-h intervals at six core sites and at 25 satellite sites in and around Mexico City from 23 February to 22 March 1997. In addition, four 6-h samples were taken each day at three of the core sites. Sampling locations were selected to represent regional, central city, commercial, residential, and industrial portions of the city. Mass and light transmission concentrations were determined on all of the samples, while elements, ions and carbon were measured on approximately two-thirds of the samples. PM10 concentrations were highly variable, with almost three-fold differences between the highest and lowest concentrations. Fugitive dust was the major cause of PM10 differences, although carbon concentrations were also highly variable among the sampling sites. Approximately 50% of PM10 was in the PM2.5 fraction. The majority of PM mass was comprised of carbon, sulfate, nitrate, ammonium and crustal components, but in different proportions on different days and at different sites. The largest fine-particle components were carbonaceous aerosols, constituting approximately 50% of PM2.5 mass, followed by approximately 30% secondary inorganic aerosols and approximately 15% geological material. Geological material is the largest component of PM10, constituting approximately 50% of PM10 mass, followed by approximately 32% carbonaceous aerosols and approximately 17% secondary inorganic aerosols. Sulfate concentrations were twice as high as nitrate concentrations. Sulfate and nitrate were present as ammonium sulfate and ammonium nitrate. Approximately two-thirds of the ammonium sulfate measured in urban areas appears to have been transported from regions outside of the study domain, rather than formed from emissions in the urban area. Diurnal variations are apparent, with two-fold increases in concentration from night-time to daytime. Morning samples had the highest PM2.5 and PM10 mass, secondary inorganic aerosols and carbon concentrations, probably due to a shallow surface inversion and rush-hour traffic.

Aerosols↗