Abstract  Research on the prevalence, course, and correlates of behavior problems in preschool children was examined. Prospective epidemiological studies and follow-up studies of clinical/high risk samples indicate that serious externalizing problems identified early often persist. Negative, inconsistent parental behavior and high levels of family adversity are associated with the emergence of problems in early childhood and predict their persistence to school age. Studies are examined from a developmental perspective and integrated with research on optimal parent-child relationships. The severity of initial problems and family context are related to different developmental outcomes.

Abstract  A meta-analysis of 47 studies was used to shed light on inconsistencies in the concurrent association between parental caregiving and child externalizing behavior. Parent-child associations were strongest when the measure of caregiving relied on observations or interviews, as opposed to questionnaires, and when the measure tapped combinations of parent behaviors (patterns), as opposed to single behaviors. Stronger parent-child associations were also found for older than for younger children, and for mothers than for fathers. Finally, externalizing was more strongly linked to parental caregiving for boys than for girls, especially among preadolescents and their mothers. The meta-analysis helps account for inconsistencies in findings across previous studies and supports theories emphasizing reciprocity of parent and child behavior.

Abstract  Newborn status, ratings of temperament, and heretofore neglected experiential (parenting) antecedents of hyperactivity were evaluated in a prospective, longitudinal investigation. The experiential variables were derived from a developmental theory of arousal modulation in the early years. Patterns of maternal intrusive care, seductive behavior, and overstimulation were assessed at 6 months, 2 years, and 3 1/2 years, respectively. 2 of these 3 variables significantly predicted hyperactivity in kindergarten at age 5 or 6, as determined by clinically validated ratings made by teachers. Of the 38 early child variables, which included neonatal behavioral assessments and ratings of activity level by parents and observers on many occasions during the first 2 1/2 years, only the motor maturity factor from 2 composited Brazelton exams yielded a significant relation. In addition, a measure of distractibility at 42 months was predictive of hyperactivity. Although other child measures may prove to be more powerful than those we tested, it will remain the case that prospective data are a critical arbiter of etiological factors in hyperactivity. Such data have important implications for both diagnosis and treatment.

Abstract  Generally recognized as the standard work in its field, Behavioral, Social, and Emotional Assessment of Children and Adolescents provides a comprehensive foundation and guide for conducting conceptually sound, culturally responsive, and ecologically-oriented assessments of student social and emotional behavior. It is aimed at graduate students, practitioners, and researchers in the fields of school psychology, child clinical psychology, and special education, but will also be of interest to those in related disciplines such as counseling psychology, child psychiatry, and social work. Keeping intact many of the same premises and pedagogy of the previous editions, this revised and updated fourth edition has been re-organized to emphasize culturally responsive reflective practice, with added content including updated assessment tools and strategies to be used within a Response to Intervention (RtI) framework. In addition to updating all chapters to reflect current research and data, authors Sara Whitcomb and Kenneth Merrell move away from a more narrow view of social skills to reflect an expanded notion of strengths-based assessment, which includes such traits as coping skills, resilience, problem-solving ability, emotional knowledge, and empathy. Throughout, they strive to increase professional standards in the practice of psychological and educational assessment of children and adolescents, providing a solid, evidence-based foundation for assessment.

Abstract  The purpose of this study was to confirm, using longitudinal observations in a normal population, that the rate of decline in renal function (creatinine clearance) is inversely correlated with blood pressure. The negative regression coefficients plotting individual rates of decline over time (Bcr) against mean blood pressures (MBP) were highly significant (p less than 0.001) for all subjects and subjects in category 3 (normals). Although the Bcr also decreases significantly with age and MBP increases with age suggesting this might be an age effect, a multiple regression analysis shows that both MBP and age as independent variables exert statistically significant effects on Bcr, the dependent variable.

Abstract  The National Emissions Inventory (NEI) is a comprehensive and detailed estimate of air emissions of both Criteria and Hazardous air pollutants from all air emissions sources. The NEI is prepared every three years by the USEPA based primarily upon emission estimates and emission model inputs provided by State, Local, and Tribal air agencies for sources in their jurisdictions, and supplemented by data developed by the USEPA. The 2008 NEI was built from emissions data in the Emissions Inventory System (EIS). The data presented below are for the 2008 NEI version 3. For a detailed list of caveats and changes from version 2, and older versions, please see the Version 3 issues file.

Abstract  OBJECTIVE: We measured lead and other heavy metals in dust during older housing demolition and effectiveness of dust suppression. METHODS: We used American Public Housing Association Method 502 and U.S. Environmental Protection Agency Methods SW3050B and SW6020 at 97 single-family housing demolition events with intermittent (or no) use of water to suppress dust at perimeter, non-perimeter, and locations without demolition, with nested mixed modeling and tobit modeling with left censoring. RESULTS: The geometric mean (GM) lead dust fall during demolition was 6.01 micrograms of lead per square foot per hour (μg Pb/ft(2)/hour). GM lead dust fall was 14.18 μg Pb/ft(2)/hour without dust suppression, but declined to 5.48 μg Pb/ft(2)/hour (p=0.057) when buildings and debris were wetted. Significant predictors included distance, wind direction, and main street location. At 400 feet, lead dust fall was not significantly different from background. GM lead concentration at demolition (2,406 parts per million [ppm]) was significantly greater than background (GM=579 ppm, p=0.05). Arsenic, chromium, copper, iron, and manganese demolition dust fall was significantly higher than background (p<0.001). Demolition of approximately 400 old housing units elsewhere with more dust suppression was only 0.25 μg Pb/ft(2)/hour. CONCLUSIONS: Lead dust suppression is feasible and important in single-family housing demolition where distances between houses are smaller and community exposures are higher. Neighbor notification should be expanded to at least 400 feet away from single-family housing demolition, not just adjacent properties. Further research is needed on effects of distance, potential water contamination, occupational exposures, and water application.

Abstract  The effects of different concentration Pb2+ (0.1, 1, 10, 50, 100, 200, 400 mg/litre) in BG11 on the growth, morphostructure and physiological characteristics of Chlorococcum sp. were studied. Compared with the cell cultured in BG11, the cell cultured in low concentrations (≤50 mg/litre) showed few changes in pigment and thickness of cell wall; the cell wall of the cell cultured in high concentrations of Pb2+ (>50 mg/litre) became thicker, and the pigment decreased and the pyrenoid disappeared. When the concentrations of Pb2+ were 0.1-10 mg/litre, the growth of Chlorococcum sp. showed no obvious difference compared with the control; when the concentration of Pb2+ was 50 mg/litre, Chlorococcum sp. could maintain certain growth rate yet; however, when the concentration of Pb2+ was higher than 100 mg/litre, the growth of Chlorococcum sp. was inhibited markedly. The contents of Chl a+Chl b or Chl a decreased gradually with the increase of the concentrations of Pb2+ in the medium. The photosynthesis of Chlorococcum sp. decreased gradually with the increase of Pb2+ concentrations, when the concentration of Pb2+ was higher than 100 mg/litre, the photosynthesis of Chlorococcum sp. could not be detected; when the concentration of Pb2+ was less than 50 mg/litre, the respiration of Chlorococcum sp. increased gradually with the increase of Pb2+ concentrations, and when the concentration of Pb2+ was higher than 50 mg/litre, they decreased gradually with the increase of Pb2+ concentrations. The content of malondiadehyde and activities of superoxide dismutase and peroxidase increased gradually with the increase of Pb2+ concentrations, and the activity of catalase increased at beginning and then decreased with the increase of Pb2+ concentrations. When the concentration of Pb2+ was ≤100 mg/litre, the removal rate of Chlorococcum sp. on Pb2+ was >95%, and it was up 56.7% yet when the concentration of Pb2+ was 400 mg/litre. The results demonstrated that the Chlorococcum sp. could be applied to the treatment of wastewater containing Pb2+, because the Chlorococcum sp. could endure the stress of Pb2+ and was of high removal rate on Pb2+.

Abstract  The term 'air pollution' is used to describe the presence of chemicals or materials in the atmosphere that produce poor air quality. Air pollutants may be classified into four principal categories which include anthropogenic (man-made; e.g. combustion products), biogenic (biological; e.g. pollen, allergens), technogenic (technology; e.g. metal aerosols or smelter) and geogenic (geological; e.g. erosion of earth, i.e. minerals, volcanic ash). From these categories are derived the seven main pollutants of human health concern, i.e. carbon monoxide, nitrogen dioxide, ozone, sulphur dioxide, hydrocarbons, lead, and particulate matter (PM). The common provenance of all these emissions is from the combustion of fossil fuels (e.g. coal, petrol and diesel), biomass (e.g. cooking) and tobacco smoke. PM is now considered to be the most precarious of pollutants, with the combustion-derived nano-particles being linked to a myriad of premature and excess deaths world-wide; especially for persons with pre-existing cardiovascular disorders. This meeting intended to bring together scientists from a host of disciplines (toxicologists, biologists, chemists, physicists and material scientists) that work at the bio-particulate interface. It aimed to present and discuss, via topical 'break-out' sessions, the current thoughts on the 'burden to human health' following exposure to and harm from combustion-derived particles. Furthermore, strategies for 'harm reduction' were another feature of this cross-disciplinary meeting. The final objectives were to identify biomarkers of exposure and harm to these inhalation hazards. All topics covered sought to find biomarker indices for human health effects.

Abstract  Freshwater fish demand in West Java is supported by cage aquaculture in reservoirs. Cirata Reservoir is one of three cascading hydropower reservoirs built along the Citarum River that receives domestic and industrial wastes. Water pollution by heavy metals, such as copper and lead, increases the health risk of humans who consume the fish. The study was aimed to evaluate the concentration of copper and lead in fish, specifically on Cyprinus carpio, that are widely cultivated in the Cirata Reservoir. Two sizes of fish were collected from five sampling points around floating-cage area. The liver of the fish was found to contain the highest copper level, followed by gills, skin, and muscle. In contrast, lead was also high in the liver, followed by skin, gills, and the muscle, but the copper concentration found in the tissues studied was much higher (31.111±17.911 mg/kg dry wt) than the lead content (0.290±0.346 mg/kg dry wt). The concentration of metals in smaller fish was always higher than that in bigger fish. The metals content was also compared to those in fish exposed in a semistatic laboratory-scale study using Oreochromis niloticus. After 28 days exposure with 0.01 mg Cu/L, fish accumulated 21.53 mg Cu/kg dry wt, whereas for Pb exposure of 0.016 mg/L, fish accumulated up to 7 mg/kg dry wt. However, estimates of Cu and Pb intake from C. carpio consumption were still below the average daily intake (ADI) limit. This study suggested that monitoring of water quality and heavy metals in cultured fish is important in protecting human health.

Abstract  Objectives: As demonstrated by many studies, emergency department (ED) visits for asthma can be associated with air pollution exposures. The aim of this study was to examine and assess the potential relations between ED visits for asthma and the concentrations of ambient air pollutants. Materials and Methods: Generalized linear mixed model was applied to study 62,563 ED visits for asthma (ICD-9: 493) in Edmonton, Canada. Two age groups, with 10 years of age as a separator, were considered by gender and season of the year: all (I–XII), warm (IV–IX) and cold (X–III). Results: The percentage increase in daily ED visits for asthma was 17.8% (95% CI: 7.1–29.5) and 13.8% (95% CI: 3.3–25.3) for females below 10 years of age, in the period of IV–IX, for current day and 1-day lagged exposure to ozone (O3), respectively. The percentage increase was 19.2% (95% CI: 11.4–27.6) for males below 10 years of age, in the period of IV–IX, for 2-day lagged exposure to nitrogen dioxide (NO2). Conclusions: The fi ndings provide support for the hypothesis that ED visits for asthma are associated with exposure to O3. This study underlines the signifi cant role of air pollutants as triggering asthma attacks.

Abstract  Estimates of carbon uptake and storage based on global nitrogen deposition, C:N ratios for typical terrestrial ecosystems, and recent ecosystem-scale nutrient studies indicate that 1.0-2.3 Gt C yr-1 of carbon storage may be stimulated by anthropogenically caused increases in nitrogen deposition in the past century. Sixty four to eighty four percent of global nitrogen uptake appears to occur on northern continents, with the remainder largely in northern coastal oceans. Increased nitrogen input by terrestrial ecosystems causes increased accumulation of carbon as plant tissue, with C:N ratios generally 50 to 200:1. Calculations suggest that northern continents are a major sink for carbon and that nitrogen-stimulated carbon uptake may more or less balance global carbon losses to the atmosphere from deforestation and agriculture. Much of the uptake appears to occur in aggrading forests, and the question of how long it can continue has important consequences for global carbon budgets.

Abstract  Short-term effects of air pollution on common morbidity are largely unknown. The authors explored links between daily levels of air pollution (nitrogen dioxide, ozone, and particulate matter less than 10 lm in diameter (PM10)) and medical home visits made for diverse reasons in Bordeaux, France, during 2000–2006. Daily numbers of visits were obtained from a network of general practitioners. The excess relative risk (ERR) of a visit for each indicator associated with increased pollutant levels was estimated by fitting a Poisson regression model, controlling for well known confounding factors and temporal trends. Positive and significant associations were found between air pollution and most health indicators. A 10-lg/m3 increase in PM10 levels was associated with increases in visits for upper and lower respiratory diseases (ERRs were 1.5% (95% confidence interval (CI): 0.3, 2.7) and 2.5% (95% CI: 0.5, 4.4), respectively), headache and asthenia (ERR = 3.5%, 95% CI: 1.3, 5.9), and skin rash and conjunctivitis (ERR= 3.2%, 95% CI: -0.2, 6.8). Significant associations were also found between nitrogen dioxide and ozone and several health indicators. Distributed-lag models showed no harvesting effect, and some effects persisted up to 15 days after exposure increased. These results suggest that considering only the most severe effects of air pollution leads to underestimation of its impact on public health.

Abstract  The historical and ongoing lead (Pb) contamination caused by the 20th-century use of leaded gasoline was investigated by an analysis of bottom sediment in eight small rural reservoirs in eastern Kansas, USA. For the reservoirs that were completed before or during the period of maximum Pb emissions from vehicles (i.e., the 1940s through the early 1980s) and that had a major highway in the basin, increased Pb concentrations reflected the pattern of historical leaded gasoline use. For at least some of these reservoirs, residual Pb is still being delivered from the basins. There was no evidence of increased Pb deposition for the reservoirs completed after the period of peak Pb emissions and (or) located in relatively remote areas with little or no highway traffic. Results indicated that several factors affected the magnitude and variability of Pb concentrations in reservoir sediment including traffic volume, reservoir age, and basin size. The increased Pb concentrations at four reservoirs exceeded the U.S. Environmental Protection Agency threshold-effects level (30.2 mg kg(-1)) and frequently exceeded a consensus-based threshold-effects concentration (35.8 mg kg(-1)) for possible adverse biological effects. For two reservoirs it was estimated that it will take at least 20 to 70 yr for Pb in the newly deposited sediment to return to baseline (pre-1920s) concentrations (30 mg kg(-1)) following the phase out of leaded gasoline. The buried sediment with elevated Pb concentrations may pose a future environmental concern if the reservoirs are dredged, the dams are removed, or the dams fail.

Abstract  Surface ozone concentration and surface air temperature was measured hourly at three coastal sites, four low elevation inland sites and two high elevation inland sites in southwestern Sweden. Diurnal ozone concentration range (DOR) and diurnal temperature range (DTR) were strongly correlated, both spatially and temporally, most likely because both depended on atmospheric stability. Accumulated ozone exposure above a threshold concentration of x nmol mol(-1) (AOTx) was estimated from time-integrated ozone concentration (as from diffusive sampling) and measures of ozone concentration variability. Two methods both estimated 24-h AOTx with high accuracy (modelling efficiencies >90% for x <= 40 nmol mol(-1)). Daytime (08:00-20:00) AOTx could not be equally well estimated. Estimates were better for lower AOT thresholds. Diffusive ozone concentration sampling, combined with hourly temperature monitoring, could be a valuable complement to ozone concentration monitoring with continuous instruments. (C) 2009 Elsevier Ltd. All rights reserved.

Abstract  Firearm instructors represent a particular occupational group exposed to low lead (Pb) doses. Even low blood lead levels (PbB) of this metal can cause an increase of blood pressure (BP). OBJECTIVE: To assess the Pb exposure of the firearm instructors of the Italian State Police (SP) and the effects of Pb on their PA. SUBJECTS AND METHODS: 376 instructors were studied, including 188 subjects working at indoor and 188 at outdoorfiring ranges. After obtaining informed consent, information on work, social and pathological history was collected and measurements of body mass index (BMI), BP and blood lead (PbB) level were obtained from the medical records. RESULTS: The mean PbB level of the instructors of outdoor ranges (6.7 +/- 5.3 microg/dl) was significantly lower than those of indoor ranges (8.5 +/- 7.6 microg/dl). In the instructors of outdoor ranges the diastolic BP (DBP) was significantly influenced by BMI and PbB, also considering the common confounding factors. DISCUSSION: The mean PbB level of the firearm instructors of the Italian SP resulted to be clearly below the biological limit value for Pb. In the instructors of outdoor ranges the even low PbB levels detected were able to determine a slight, but significant increase of DBP, also after correction for the main confounding variables. It is therefore necessary to keep on effecting biological monitoring and health surveillance of firearm instructors of SP and to promote the reduction of their body weight.

Abstract  Psychological tests as developed and validated in the field of differential psychology have a longstanding tradition as tools to study individual differences. In clinical neuropsychology, global or more specific tests are used as neuropsychological tools in the differential diagnosis of various forms of brain damage or neurobehavioral dysfunction following chemical insults, such as mental sequelae of prenatal alcohol consumption by pregnant mothers (fetal alcohol syndrome) or of maternal thyroid deficiency during pregnancy. Psychometric tests are constructed to fulfill basic quality criteria, namely objectivity, reliability and validity. For strictly diagnostic purposes in individual cases they must also possess normative values based on representative reference groups. Intelligence tests or their developmental variants are often used as endpoints in environmental health research for studying neurodevelopmental adversity due to early exposure to neurotoxic chemicals in the environment. Intelligence as treated in psychology is a complex construct made up of specific cognitive functions which usually cover verbal, numerical and spatial skills, as well as perceptual speed, memory and reasoning. In this paper, case studies covering neurodevelopmental adversity of inorganic lead, of methylmercury and of polychlorinated biphenyls (PCBs) are reviewed, and the issue of postnatal behavioral sequelae of prenatal exposure is covered. In such observational studies precautions must be taken in order to avoid pitfalls of causative interpretation of associations between exposure and neurobehavioral outcome. This requires consideration of co-exposure and confounding. Important confounders considered in most modern developmental cohort studies are maternal intelligence and quality of the home environment.

Abstract  OBJECTIVE: Air pollution can promote airway inflammation, posing significant health risks for children with chronic respiratory problems. However, it is unknown whether this process is reversible, so that limiting pollution will benefit these children. We measured the short-term response of allergic asthmatic children exposed to a real-life reduction in outdoor air pollution by using noninvasive biomarkers of airway inflammation and function. PATIENTS AND METHODS: Thirty-seven untreated allergic children with mild persistent asthma were recruited from a highly polluted urban environment and relocated to a less polluted rural environment. Air pollution, pollen counts, and meteorological conditions were carefully monitored at both sites. Nasal eosinophils, fractional exhaled nitric oxide, peak expiratory flow, and urinary leukotriene E(4) were measured first in the urban environment and then again 7 days after relocation to the rural environment. RESULTS: One week after relocation to the rural environment, we measured, on average, a fourfold decrease in nasal eosinophils and significant decrease in fractional exhaled nitric oxide. We also noted an improvement in lower airway function, reflected by highly significant increase in peak expiratory flow. In contrast, mean urinary leukotriene E(4) concentration remained unchanged after 1 week of exposure to the rural environment. CONCLUSIONS: Better air quality is associated with a rapid reduction of airway inflammation in allergic asthmatic children. Nasal eosinophils and fractional exhaled nitric oxide are sensitive indicators of this effect, and their rapid decline is paralleled by improved airway function measured by peak expiratory flow. Leukotriene synthesis has a more variable response to environmental modifications.

Abstract  BACKGROUND: Tumor necrosis factor (TNF)-alpha has a recognized role in respiratory pathophysiology. One genetic variant (G-308A) in the promoter region affecting the expression of this cytokine may contribute to airway inflammatory diseases, but the studies on bronchitic symptoms were still inconclusive. Because ozone produces oxidative stress, increased airway TNF, and inflammation, the associations of the TNF-308 polymorphism with bronchitic symptoms may vary by ambient ozone exposure. METHODS: We studied associations of TNF-308 genotype with bronchitic symptoms among asthmatic children in Children's Health Study. The association of TNF G-308A polymorphism with bronchitic symptoms was investigated and we also determined whether the associations vary with ambient ozone exposure. RESULTS: Asthmatic children with TNF-308 GG genotype had a significantly reduced risk of bronchitic symptoms with low-ozone exposure (adjusted OR: 0.53; 95% CI: 0.31-0.91). The risk was not reduced in children living in high-ozone communities (adjusted OR: 1.42; 95% CI: 0.75-2.70). This difference in genotypic effects between low- and high-ozone environments was statistically significant among asthmatics (P for interaction = 0.01), but insignificant among nonasthmatic children. CONCLUSION: Our findings suggest a role of gene-environmental interactions on the occurrence of bronchitic symptoms among children with asthma.

Abstract  Emissions from fossil fuel combustion and biomass burning reduce local air quality and affect global tropospheric chemistry. Nitrogen oxides are emitted by all combustion processes and play a key part in the photochemically induced catalytic production of ozone, which results in summer smog and has increased levels of tropospheric ozone globally. Release of nitrogen oxide also results in nitric acid deposition, and--at least locally--increases radiative forcing effects due to the absorption of downward propagating visible light. Nitrogen oxide concentrations in many industrialized countries are expected to decrease, but rapid economic development has the potential to increase significantly the emissions of nitrogen oxides in parts of Asia. Here we present the tropospheric column amounts of nitrogen dioxide retrieved from two satellite instruments GOME and SCIAMACHY over the years 1996-2004. We find substantial reductions in nitrogen dioxide concentrations over some areas of Europe and the USA, but a highly significant increase of about 50 per cent-with an accelerating trend in annual growth rate-over the industrial areas of China, more than recent bottom-up inventories suggest.

Abstract  Objective: The estimated mortality rate associated with ambient air pollution based on general population studies may not be representative of the effects on certain subgroups. The objective of the present study was to determine the influence of relatively high concentrations of air pollution on mortality in a general population sample and in the very elderly. Study design: Daily time-series analyses tested the association between daily air pollution and daily mortality in seven Chilean urban centers during 1997-2003. Results were adjusted for day of the week and humidex. Results: Daily averaged particulate matter with aerodynamic matter < 10 Ám (PM10) was 84.88 Ág/m3, sulfur dioxide was 14.08ppb, and carbon monoxide was 1.29 ppb. The 1-hr maximum ozone was 100.13 ppb. The percentage increases in nonaccidental mortality associated with an increase in PM10 equivalent to its mean were 4.53 (t-ratio 1.52) for those < 65 years and 14.03 (3.87) for those > 85 years. Respective values were 4.96 (1.17) and 8.56 (2.02) for O3 ; 4.77 (2.50) and 7.92 (3.23) for SO2 ; and 4.10 (2.52) and 8.58 (4.45) for CO. Conclusion: Our results suggest that the very elderly are particularly susceptible to dying from air pollution. Concentrations deemed acceptable for the general population may not adequately protect the very elderly.

Abstract  Exposures to particulate matter and gaseous air pollutants have been associated with respiratory tract inflammation, disruption of the nasal respiratory and olfactory barriers, systemic inflammation, production of mediators of inflammation capable of reaching the brain and systemic circulation of particulate matter. Mexico City (MC) residents are exposed to significant amounts of ozone, particulate matter and associated lipopolysaccharides. MC dogs exhibit brain inflammation and an acceleration of Alzheimer's-like pathology, suggesting that the brain is adversely affected by air pollutants. MC children, adolescents and adults have a significant upregulation of cyclooxygenase-2 (COX2) and interleukin-1beta (IL-1beta) in olfactory bulb and frontal cortex, as well as neuronal and astrocytic accumulation of the 42 amino acid form of beta -amyloid peptide (Abeta 42), including diffuse amyloid plaques in frontal cortex. The pathogenesis of Alzheimer's disease (AD) is characterized by brain inflammation and the accumulation of Abeta 42, which precede the appearance of neuritic plaques and neurofibrillary tangles, the pathological hallmarks of AD. Our findings of nasal barrier disruption, systemic inflammation, and the upregulation of COX2 and IL-1beta expression and Abeta 42 accumulation in brain suggests that sustained exposures to significant concentrations of air pollutants such as particulate matter could be a risk factor for AD and other neurodegenerative diseases.

Abstract  BACKGROUND: Health concerns about the exposure to genotoxic and carcinogenic agents in the air are particularly significant for outdoor workers in less developed countries. AIMS: To investigate the association between personal exposure to a group of air pollutants and severity of DNA damage in outdoor workers from two Mexican cities. METHODS: DNA damage (Comet assay) and personal exposure to volatile organic compounds, PM(2.5), and ozone were investigated in 55 outdoor and indoor workers from MÚxico City and Puebla. RESULTS: In MÚxico City, outdoor workers had greater DNA damage, reflected by a longer tail length, than indoor workers (median 46.8 v 30.1 mum), and a greater percentage of highly damaged cells (cells with tail length > or =41 microm); in Puebla, outdoor and indoor workers had similar DNA damage. There were more alkali labile sites in outdoor than indoor workers. The DNA damage magnitude was positively correlated with PM(2.5) and ozone exposure. Outdoor and indoor workers with > or =60% of highly damaged cells (highly damaged workers) had significantly higher exposures to PM(2.5), ozone, and some volatile organic compounds. The main factors associated with the highly damaged workers were ozone, PM(2.5), and 1-ethyl-2-methyl benzene exposure. CONCLUSIONS: With this approach, the effects of some air pollutants could be correlated with biological endpoints from the Comet assay. It is suggested that the use of personal exposure assessment and biological endpoints evaluation could be an important tool to generate a more precise assessment of the associated potential health risks.