Health Epidemiological Studies Research Articles

Prevalence and Characterization of Staphylococcus aureus Isolated From Retail Vegetables in China.

Staphylococcus aureus is a pathogen associated with serious community and hospital-acquired diseases. The aim of this study was to investigate the prevalence of S. aureus from retail vegetables in China and then characterized S. aureus isolates by antibiotic resistance, staphylococcal enterotoxin genes, spa-typing and multi-locus sequence typing. Of 419 retail vegetable samples from 39 cities in China during 2011–2016, 24 (5.73%) samples were positive for S. aureus and the geometric mean was 3.85 MPN/g. The prevalence of S. aureus was highest in lettuce (13/84, 15.48%) followed by tomato (7/110, 6.36%), caraway (2/87, 2.30%), and cucumber (2/128, 1.56%), whereas other vegetables were free of S. aureus. A total of 30 isolates were analyzed. For antibiotics susceptibility test, most isolates (93.3%) were resistant to ampicillin and penicillin, whereas all isolates were susceptible to linezolid, trimethoprim/sulphamethoxazole 1:19, nitrofurantoin, rifampicin, and teicoplanin. All isolates (30/30, 100%) were resistant or intermediate resistant to more than three tested antibiotics, including 9 isolates (30%) were resisted more than 10 antibiotics. Five isolates were resistant to cefoxitin and carried mecA genes which confirmed as MRSA. Of the 18 investigated SE genes, the sem gene was the most frequently detected (86.7%) followed by the sec (83.3%), sep (70.0%), seg (56.7%), sel (53.3%), seh (50.0%), seq (50.0%), sej (46.7%), seb (36.7%), sen (36.7%), and ser (33.3%) genes were harbored by more than one third of the isolates, whereas the seo and seu were detected in only 6.75% of the isolates. MLST and spa typing observed high genetic diversity in S. aureus isolated from retail vegetable in China. ST59-t437 was the predominant types (3/5, 60%) of MRSA isolates, whereas ST188-t189 was the predominant types (7/25, 28%) of MSSA isolates. Our study reflects that the retail vegetable in China could be contaminated with S. aureus but the levels of S. aureus were not very excessive. In addition, these isolates had virulence potential, most of them were enterotoxigenic and multiple antimicrobial resistance, should be draw public attention. These data have signification implications for epidemiological and public health studies of this pathogen.

Knowledge and causal attributions for mental disorders in HIV-positive children and adolescents: results from rural and urban Uganda

Increasing availability of antiretroviral treatment (ART) has led HIV to be considered a chronic disease, shifting attention to focus on quality of life including mental wellbeing. We investigated knowledge and causal attributions for mental disorders in HIV-positive children and adolescents in rural and urban Uganda. This qualitative study was nested in an epidemiological mental health study among HIV-positive children and adolescents aged 5–17 years in rural and urban Uganda. In-depth interviews were conducted with caregivers of HIV-positive children (5–11 years) and adolescents (12–17 years) in HIV care. Interviews were audio recorded with permission from participants and written consent and assent sought before study procedures. Thirty eight participants (19 caregivers, 19 children/adolescents) were interviewed. Age range of caregivers was 28–69 years; majority were female (17). Caregivers had little knowledge on mental disorders ;only 3 related the vignette to a mental problem and attributed it to: improper upbringing, violence, poverty and bereavement. Five adolescents identified vignettes as portraying mental disorders caused by: ill-health of parents, bereavement, child abuse, discrimination, HIV and poverty. Caregivers are not knowledgeable about behavioural and emotional challenges in HIV-positive children/adolescents. Mental health literacy programmes at HIV care clinics are essential to enhance treatment-seeking for mental health.

Response rate differences between web and alternative data collection methods for public health research: a systematic review of the literature.

To systematically review the literature and compare response rates (RRs) of web surveys to alternative data collection methods in the context of epidemiologic and public health studies. We reviewed the literature using PubMed, LILACS, SciELO, WebSM, and Google Scholar databases. We selected epidemiologic and public health studies that considered the general population and used two parallel data collection methods, being one web-based. RR differences were analyzed using two-sample test of proportions, and pooled using random effects. We investigated agreement using Bland-and-Altman, and correlation using Pearson's coefficient. We selected 19 studies (nine randomized trials). The RR of the web-based data collection was 12.9 percentage points (p.p.) lower (95% CI = - 19.0, - 6.8) than the alternative methods, and 15.7 p.p. lower (95% CI = - 24.2, - 7.3) considering only randomized trials. Monetary incentives did not reduce the RR differences. A strong positive correlation (r = 0.83) between the RRs was observed. Web-based data collection present lower RRs compared to alternative methods. However, it is not recommended to interpret this as a meta-analytical evidence due to the high heterogeneity of the studies.

Surface water flooding, groundwater contamination, and enteric disease in developed countries: A scoping review of connections andconsequences.

Significant volumes of research over the past four decades has sought to elucidate the social, infrastructural, economic, and human health effects of climate change induced surface flooding. To date, epidemiological and public health studies of flooding events have focused on mental health effects, vector-borne diseases, and infectious enteric disease due to floodwater contact (i.e. typically low consumption rates). The inherent nature of groundwater (i.e. out of sight, out of mind) and the widely held belief that aquifers represent a pristine source of drinking water due to natural attenuation may represent the "perfect storm" causing direct consumption of relatively large volumes of surface flood-contaminated groundwater. Accordingly, the current study sought to systematically identify and synthesize all available peer-reviewed literature pertaining to the nexus between surface flooding, groundwater contamination and human gastroenteric outcomes. Just 14 relevant studies were found to have been published during the period 1980-2017, thus highlighting the fact that this potentially significant source of climate-related exposure to environmental infection has remained understudied to date. Studies differed significantly in terms of type and data reporting procedures, making it difficult to discern clear trends and patterns. Approximately 945 confirmed cases of flood-related enteric disease were examined across studies; these concurred with almost 10,000 suspected cases, equating to approximately 20 suspected cases per confirmed case. As such, no regional, national or global estimates are available for the human gastrointestinal health burden of flood-related groundwater contamination. In light of the demonstrable public health significance of the concurrent impacts of groundwater susceptibility and climate change exacerbation, strategies to increase awareness about potential sources of contamination and motivate precautionary behaviour (e.g. drinking water testing and treatment, supply interruptions) are necessary. Mainstreaming climate adaptation concerns into planning policies will also be necessary to reduce human exposure to waterborne sources of enteric infection.

Education, bilingualism, and cognitive trajectories: Sacramento Area Latino Aging Study (SALSA).

This study examined the influence of education, country where education occurred, and monolingual-bilingual (English/Spanish) language usage on late life cognitive trajectories in the Sacramento Area Latino Study on Aging (SALSA), an epidemiological study of health and cognition in Hispanics, mostly of Mexican origin, age 60 and over (N = 1,499). SALSA followed a large cohort of older Latinos for up to 7 assessment waves from 1998 to 2007. Global cognition was assessed by using the Modified Mini Mental State Examination, and the Spanish English Verbal Learning Test was used to measure episodic memory. Education, country of origin, and language usage patterns were collected at the baseline assessment and used as predictors of longitudinal trajectories of cognition. Parallel process mixed effects models were used to examine effects of education and language variables on baseline cognition and rate of cognitive decline. Mixed effects longitudinal models showed that education had strong effects on baseline global cognition and verbal memory but was not related to decline over up to 9 years of longitudinal follow-up. Differences in education effects between subgroups educated in Mexico and in the United States were minor. Monolingual-bilingual language usage was not related to cognitive decline, and bilinguals did not significantly differ from monolingual English speakers on baseline cognitive scores. Hypotheses that higher education and bilingualism protect against late life cognitive decline were not supported and education effects on late-life cognitive trajectories did not substantially differ across U.S.- and Mexico-educated groups. (PsycINFO Database Record

Towards a critical epidemiology approach for applied sexual health research.

Critical approaches may benefit epidemiological studies of sexual health. This article proposes a critical approach, reconcilable with social epidemiological enquiry. Key aims of critical epidemiology for sexual health are identified, from which three criticisms of practice emerge: (1) lack of attention to socio-cultural contexts, (2) construction of 'risk' as residing in the individual and (3) enactment of public health agendas which privilege and pathologise certain behaviours. These reflect and construct an apolitical understanding of population health. This article proposes features of a critical epidemiology that represent a morally driven re-envisioning of the focus, analysis and interpretation of epidemiological studies of sexual health.

Cognitive Testing of the Brief Breastfeeding and Milk Expression Recall Survey.

Major U.S. federal maternal and child health surveys collect an infant feeding history for children under 6 years of age using survey questions that have changed little over decades. Yet, infant feeding and lactation practices have changed with the increasing popularity of milk expression (pumping). Cognitive interviews were conducted to test the 9-item Brief Breastfeeding and Milk Expression Recall Survey (BaByMERS) with a diverse sample of 15 U.S. mothers of children 1-5 years of age. A 42-item coding scheme was applied to identify interviewer and respondent problems in fielding and answering the questions. Problems were examined in relation to demographics and infant feeding and lactation history. The extent of problems was modest. Of 42 possible problem codes, only 9 were identified as actual problems for one or more respondents on one or more questions. The most common problems involved uncertainty about the timing of when one started expressing milk, making a mental shift to realize that maternal milk expression and the child's consumption of that milk could be distinct concepts, and difficulty with certain terms or phrases. Problems tended to arise among mothers with more complex infant feeding or lactation histories, who also tended to be those with higher levels of education. BaByMERS is a promising, brief tool for collecting a recalled infant feeding or lactation history among mothers with young children. Future research can evaluate additional characteristics of the tool to further confirm its utility for large epidemiological studies of maternal and child health.

Distance, Duration, and Velocity in Cycle Commuting: Analyses of Relations and Determinants of Velocity.

Background: The distance, duration, and velocity of cycling for transport purposes are used in health economic assessments, epidemiological studies, traffic modelling, and planning. It is therefore of value to determine relevant levels for them, and analyze how they relate, as well as to what extent other relevant variables may affect cycling velocities. 1661 cycle commuters (34% males) in Greater Stockholm, Sweden have been studied for that purpose. Methods: The participants were recruited with advertisements. They received questionnaires and individually adjusted maps to draw their normal cycling route. Route distances were measured by a criterion method. Age, sex, weight, height, and cycling durations to work were self-reported. The commuting routes were positioned in relation to inner urban and/or suburban–rural areas. Linear multiple regression analyses were used. Results: Cycling speeds were positively related to commuting distances or durations, being male, of younger age, having higher body weight but lower body mass index (BMI), and using the last digits 1–4 or 6–9 in duration reports (as compared to 0 and 5), as well as cycling in suburban (versus inner urban) areas. Conclusions: The study provides new knowledge about how distance and duration, as well as other factors, relate to the velocity of commuter cycling. It thereby enables the use of more appropriate input values in, for instance, health economic assessments and epidemiological health studies.

Modern forms of dental preventive care for children

Diseases of teeth and oral cavity have a high prevalence in pediatric population. In adolescents of 15-17 years, the incidence of caries in permanent teeth is higher than in children of 0-14 years. Epidemiological studies of dental health of children in various regions of the Russian Federation in 2010-2015 years showed no tendency to decrease the level of diseases of mouth and teeth. Prevalence and intensity of diseases remains at a high level. More than 80% of the surveyed children are in need of complex dental treatment. The current situation of pathology of teeth and mouth in children is due to several reasons such as low level of hygiene education, environmental degradation, poor nutrition, presence of chronic diseases, among older children, the presence of harmful habits, health-care organizations lack of effective preventive work. In turn, untreated inflammatory diseases of the oral cavity and teeth, being the source of the infection, may lead to somatic pathology of different organs and systems. The existing organization of children dental care is focused more on treatment than on prevention of diseases of teeth and oral cavity. As a rule, parents bring children to dental clinic for treatment of already developed disease. Referrals to the dentist for preventive measures are rare. In this regard, it is necessary to develop new organizational forms of dental care, from the point of view of the preventive orientation, close to children's educational organization.

Investigation and modeling of the residential infiltration of fine particulate matter in Beijing, China

ABSTRACTThe objective of this study was to estimate the residential infiltration factor (Finf) of fine particulate matter (PM2.5) and to develop models to predict PM2.5 Finf in Beijing. Eighty-eight paired indoor–outdoor PM2.5 samples were collected by Teflon filters for seven consecutive days during both non-heating and heating seasons (from a total of 55 families between August, 2013 and February, 2014). The mass concentrations of PM2.5 were measured by gravimetric method, and elemental concentrations of sulfur in filter deposits were determined by energy-dispersive x-ray fluorescence (ED-XRF) spectrometry. PM2.5 Finf was estimated as the indoor/outdoor sulfur ratio. Multiple linear regression was used to construct Finf predicting models. The residential PM2.5 Finf in non-heating season (0.70 ± 0.21, median = 0.78, n = 43) was significantly greater than in heating season (0.54 ± 0.18, median = 0.52, n = 45, p < 0.001). Outdoor temperature, window width, frequency of window opening, and air conditioner use were the most important predictors during non-heating season, which could explain 57% variations across residences, while the outdoor temperature was the only predictor identified in heating season, which could explain 18% variations across residences. The substantial variations of PM2.5 Finf between seasons and among residences found in this study highlight the importance of incorporating Finf into exposure assessment in epidemiological studies of air pollution and human health in Beijing. The Finf predicting models developed in this study hold promise for incorporating PM2.5 Finf into large epidemiology studies, thereby reducing exposure misclassification.Implications: Failure to consider the differences between indoor and outdoor PM2.5 may contribute to exposure misclassification in epidemiological studies estimating exposure from a central site measurement. This study was conducted in Beijing to investigate residential PM2.5 infiltration factor and to develop a localized predictive model in both nonheating and heating seasons. High variations of PM2.5 infiltration factor between the two seasons and across homes within each season were found, highlighting the importance of including infiltration factor in the assessment of exposure to PM2.5 of outdoor origin in epidemiological studies. Localized predictive models for PM2.5 infiltration factor were also developed.

Salivary DNA Methylation Profiling: Aspects to Consider for Biomarker Identification.

Is it not more comfortable to spit saliva in a tube than to be pricked with a needle to draw blood to analyse your health and disease risk? Many patients, study participants and (parents of) young children undoubtedly prefer non‐invasive and convenient procedures. Such procedures increase compliance rates especially for longitudinal prospective studies. Saliva is an attractive biofluid providing good quality DNA to study epigenetic mechanisms underlying disease across development. In this MiniReview, we will describe the different applications of saliva in the field of epigenetics, focusing on genomewide methylation analysis. Advantages of the use of saliva and its comparability with blood will be discussed, as will the challenges in data processing and interpretation. Knowledge gaps will be identified and suggestions given on how to improve the analysis, making saliva ‘the’ biofluid of choice for future biomarker initiatives in many different epidemiological and public health studies.

Protocol and methodology of the epidemiological mental health study in Andalusia: PISMA-ep

IntroductionThis is the general methods describing paper of a cross-sectional study that aims to detect the prevalence of major mental disorders in Andalusia (Southern Spain), and their correlates or potential risk factors, using a large representative sample of community-dwelling adults. Materials and methodsThis is a cross-sectional study. We undertook a multistage sampling using different standard stratification levels and aimed to interview 4518 randomly selected participants living in all 8 provinces of the Andalusian region utilising a door-knocking approach. The Spanish version of the MINI International Neuropsychiatric Interview, a valid screening instrument ascertaining ICD-10/DSM-IV compatible mental disorder diagnoses was used as our main diagnostic tool. A large battery of other instruments was used to explore global functionality, medical comorbidity, personality traits, cognitive function and exposure to psychosocial potential risk factors. A saliva sample for DNA extraction was also obtained for a sub-genetic study. The interviews were administered and completed by fully trained interviewers, despite most tools used are compatible with lay interviewer use. ResultsA total of 3892 (70.8%) of 5496 initially attempted households had to be substituted for equivalent ones due to either no response (37.7%) or not fulfilling the required participant quota (33%). Thence, out of 5496 eligible participants finally approached, 4507 (83.7%) agreed to take part in the study, completed the interview and were finally included in the study (n=4507) and 4286 (78%) participants also agreed and consented to provide a saliva sample for DNA study. On the other hand, 989 (16.3%) approached potential participants refused to take part in the study. DiscussionThis is the largest mental health epidemiological study developed in the region of Spain (Andalusia). The response rates and representativeness of the sample obtained are fairly high. The method is particularly comprehensive for this sort of studies and includes both, personality and cognitive assessments, as well as a large array of bio-psycho-social risk measures.

Examination of parental dieting and comments as risk factors for increased drive for thinness in men and women at 20-year follow-up.

Popular beliefs suggest that parents influence children's eating disorder risk through modeling pathological behaviors and attitudes, and this history may contribute to disordered eating in adulthood. However, the empirical basis for this popular thinking is limited by a reliance on cross-sectional designs that do not distinguish between maternal and paternal influences and use primarily child and adolescent samples. To address these limitations, the present study examined the impact of maternal and paternal dieting and comments about weight and eating, as reported by late adolescents, on the eating pathology of those late adolescents at 20-year follow-up. Data were drawn from a longitudinal epidemiological study of health and eating patterns in a cohort of randomly sampled college students established in 1992 (N = 799; mean age: 19.87 [±1.64] years; 70.8% women) and followed 20 years later in 2012 (N = 539). At baseline, there were no gender differences in reported rates of maternal or paternal dieting. Both men and women reported higher levels of maternal versus paternal dieting. Further, women endorsed higher levels of maternal and paternal comments on their own weight and eating. A multivariable model in women supported that maternal dieting and paternal comments significantly predicted drive for thinness at follow-up. No parental variables predicted drive for thinness in men at follow-up. While our study supports parental influence on children's eating attitudes, it suggests a need to consider gender and mode of influence. Prevention efforts focused on challenging cultural standards of appearance may benefit from incorporation of parents. © 2016 Wiley Periodicals, Inc.(Int J Eat Disord 2017; 50:490-497).

Body Mass Index as a Measure of Obesity: Racial Differences in Predictive Value for Health Parameters During Pregnancy.

As a measure of obesity, body mass index (BMI; kg/m2) is an imperfect predictor of health outcomes, particularly among African Americans. However, BMI is used to guide prenatal care. We examined racial differences in the predictive value of maternal BMI for physiologic correlates of obesity, serum interleukin (IL)-6 and C-reactive protein (CRP), as well as cesarean section and infant birth weight. One hundred five pregnant women (40 European American, 65 African American) were assessed during the second trimester. BMI was defined as per prepregnancy weight. Electrochemiluminescence and enzyme-linked immunosorbent assays were used to quantify IL-6 and CRP, respectively. Birth outcomes were determined by medical record review. Women of both races classified as obese had higher serum IL-6 and CRP than their normal-weight counterparts (ps ≤ 0.01). However, among women with overweight, elevations in IL-6 (p < 0.01) and CRP (p = 0.06) were observed among European Americans, but not African Americans (ps ≥ 0.61). Maternal obesity was a significantly better predictor of cesarean section among European Americans versus African Americans (p = 0.03) and BMI was associated with infant birth weight among European Americans (p < 0.01), but not African Americans (p = 0.94). Effects remained after controlling for gestational age at delivery, gestational diabetes, and gestational weight gain as appropriate. BMI may be a less valid predictor of correlates of overweight/obesity among African Americans versus European Americans during pregnancy. This should be considered in epidemiological studies of maternal-child health. In addition, studies examining the comparative validity of alternative/complementary measures to define obesity in pregnancy are warranted to inform clinical care.

The amount of care delivered: challenges of indices in oral health studies.

Untreated dental caries is the most prevalent medical condition worldwide, with considerable variations in prevalence between regions and countries. The care index (CI) and the restorative index (RI) are generally used to make comparisons between and within countries of levels of care delivered. However, several methodological challenges can be identified that limit the interpretation and comparison of these indices. The objective of this manuscript was to evaluate these challenges and to provide solutions. Five challenges were identified: (i) the comparability of CI and RI, (ii) the use of multiple definitions of CI and RI, (iii) CI and RI measured for surfaces or teeth, (iv) the skewness of F/D(M)F (restored teeth or surfaces as a fraction of the total number of decayed, (missing), and filled teeth or surfaces), and (v) the relationship between CI, RI and D(M)F. Time-series data were obtained - for people aged 25-44 years with low socioeconomic status - from four cross-sectional studies performed in 1995, 2002, 2007 and 2013 in the Netherlands, and those data were subjected to descriptive analyses. The analyses showed that the choice of index and definition had a major impact on the results, which varied in terms of absolute size and trends. Moreover, CI and RI are expressed as mean scores, but the distributions of F/DMF and F/DF were highly skewed. CI and RI may therefore mask groups of individuals who still need care. The proportion of individuals receiving most restorative care was much higher in the group with low levels of caries than in the groups with more caries. This implies that, when the need for care decreases over time, the restorative care indices can be expected to increase, even though there may be no improvement in the amount of care delivered. We argue that epidemiological studies of oral health in the future should clarify the definitions used to describe the care delivered and investigate subgroups of F/DMF or F/DF in categories based on the extent of caries. These figures could be used to monitor changes in treatment provision and to highlight inequalities in the provision of care.

A case study in Canada: Exploring research challenges of industrial wind turbines and health

The topic of adverse health effects associated with industrial wind turbines (IWT) is controversial and debated worldwide. Some residents living in proximity to wind energy facilities report symptoms of sleep disturbance, annoyance, headaches, ear pain/discomfort, mood disorders, stress, cardiac and blood pressure effects, reduced quality of life, and other adverse effects. In some cases, research initiatives have been the result of individuals’ complaints. The research is challenged in part by the complexities and numerous variables associated with this subject. A range of IWT research approaches, sometimes in combination with each other, has been used including self-reporting surveys, investigations and acoustical measurements. On July 12, 2012, Health Canada announced its large scale cross-sectional randomized epidemiological wind turbine noise and health study. The research was conducted by Health Canada in two Canadian provinces. Health Canada indicated its study had limitations, would not be definitive, and would not permit any conclusions to be made with respect to causality. This presentation will explore some of the inherent challenges of studying health effects associated with wind energy facilities and will consider the role of those individuals reporting adverse health effects.

Analysis of Multilocus Sequence Typing and Virulence Characterization of Listeria monocytogenes Isolates from Chinese Retail Ready-to-Eat Food.

Eighty Listeria monocytogenes isolates were obtained from Chinese retail ready-to-eat (RTE) food and were previously characterized with serotyping and antibiotic susceptibility tests. The aim of this study was to characterize the subtype and virulence potential of these L. monocytogenes isolates by multilocus sequence typing (MLST), virulence-associate genes, epidemic clones (ECs), and sequence analysis of the important virulence factor: internalin A (inlA). The result of MLST revealed that these L. monocytogenes isolates belonged to 14 different sequence types (STs). With the exception of four new STs (ST804, ST805, ST806, and ST807), all other STs observed in this study have been associated with human listeriosis and outbreaks to varying extents. Six virulence-associate genes (inlA, inlB, inlC, inlJ, hly, and llsX) were selected and their presence was investigated using PCR. All strains carried inlA, inlB, inlC, inlJ, and hly, whereas 38.8% (31/80) of strains harbored the listeriolysin S genes (llsX). A multiplex PCR assay was used to evaluate the presence of markers specific to epidemic clones of L. monocytogenes and identified 26.3% (21/80) of ECI in the 4b-4d-4e strains. Further study of inlA sequencing revealed that most strains contained the full-length InlA required for host cell invasion, whereas three mutations lead to premature stop codons (PMSC) within a novel PMSCs at position 326 (GAA → TAA). MLST and inlA sequence analysis results were concordant, and different virulence potentials within isolates were observed. These findings suggest that L. monocytogenes isolates from RTE food in China could be virulent and be capable of causing human illness. Furthermore, the STs and virulence profiles of L. monocytogenes isolates have significant implications for epidemiological and public health studies of this pathogen.

Factors Related to Gender Inequalities in the Management of Ischemic Heart Disease

Introduction: Historically, epidemiological health studies –mainly research on coronary heart disease– have focused their analysis in the male population. With this, the biological characteristics and psychosocial aspects of women have remained invisible to the patterns of health and disease, thereby generating significant differences in the treatment and outcome of these pathologies according to sex. Methodology: A qualitative descriptive analysis were carried out using phenomenological methodology by conducting semi-structured interviews with patients affected with ischemic heart disease (IHD), doctors, A&E service workers of the Hospital X (CHX) from 1 January 2013 until August of that year. Results: Both men and women referred to suspecting that the process entailed a cardiac problem. By contrast, women have confirmed that they consciously delayed the request for medical aid. Doctors expressed the idea that women are more histrionic and that it is men who delay the request for medical aid. Conclusion: Differences of perception and action generated by doctors, together with the difference in actions by patients according to sex lead to gender inequality that harms the evolution of women where these pathologies are concerned.

Air quality in the German–Czech border region: A focus on harmful fractions of PM and ultrafine particles

A comprehensive air quality study has been carried out at two urban background sites in Annaberg-Buchholz (Germany) and Usti nad Labem (Czech Republic) in the German–Czech border region between January 2012 and June 2014. Special attention was paid to quantify harmful fractions of particulate matter (PM) and ultrafine particle number concentration (UFP) from solid fuel combustion and vehicular traffic. Source type contributions of UFP were quantified by using the daily concentration courses of UFP and nitrogen oxide. Two different source apportionment techniques were used to quantify relative and absolute mass contributions: positive matrix factorization for total PM2.5 and elemental carbon in PM2.5 and chemical mass balance for total PM1 and organic carbon in PM1. Contributions from solid fuel combustion strongly differed between the non-heating period (April–September) and the heating period (October–March). Major sources of solid fuel combustion in this study were wood and domestic coal combustion, while the proportion of industrial coal combustion was low (<3%). In Usti nad Labem combustion of domestic brown coal was the most important source of organic carbon ranging from 34% to 43%. Wood combustion was an important source of organic carbon in Annaberg-Buchholz throughout the year. Heavy metals and less volatile polycyclic aromatic hydrocarbons (PAH) in the accumulation mode were related to solid fuel combustion with enhanced concentrations during the heating period. In contrast, vehicular PAH emissions were allocated to the Aitken mode. Only in Usti nad Labem a significant contribution of photochemical new particle formation (e.g. from sulfur dioxide) to UFP of almost 50% was observed during noontime. UFPs from traffic emissions (nucleation particles) and primary emitted soot particles dominated at both sites during the rest of the day. The methodology of a combined source apportionment of UFP and PM can be adapted to other regions of the world with similar problems of atmospheric pollution to calculate the relative risk in epidemiological health studies for different sub-fractions of PM and UFP. This will enhance the meaningfulness of published relative risks in health studies based on total PM and UFP number concentrations.

Current Methods and Challenges for Epidemiological Studies of the Associations Between Chemical Constituents of Particulate Matter and Health.

Epidemiological studies have been critical for estimating associations between exposure to ambient particulate matter (PM) air pollution and adverse health outcomes. Because total PM mass is a temporally and spatially varying mixture of constituents with different physical and chemical properties, recent epidemiological studies have focused on PM constituents. Most studies have estimated associations between PM constituents and health using the same statistical methods as in studies of PM mass. However, these approaches may not be sufficient to address challenges specific to studies of PM constituents, namely assigning exposure, disentangling health effects, and handling measurement error. We reviewed large, population-based epidemiological studies of PM constituents and health and describe the statistical methods typically applied to address these challenges. Development of statistical methods that simultaneously address multiple challenges, for example, both disentangling health effects and handling measurement error, could improve estimation of associations between PM constituents and adverse health outcomes.