Average Pollution Levels Research Articles

Spatial variability and population exposure to PM2.5 pollution from woodsmoke in a New South Wales country town

A portable radiance research nephelometer was used to measure the variation in woodsmoke pollution in Armidale (a small town of 22,000 people), New South Wales, Australia, on 14 winter nights in 1996. Winter nights are characterised by inversions that trap the air within the valley and reduce winds to very low speeds (averaging 0.15 m s −1). Pollution varied considerably with location. Mean scattering coefficients (bsp/10 km) for 14 measurement nights ranged from less than 1.0 on the undeveloped fringes of the city to 8.7, the latter representing a 14-night average of 200 μg m −3 of PM2.5. Pollution was generally highest in the residential areas on either side of the valley, where the smoke was generated, rather than the low-lying central creeklands. In places, average pollution levels increased 4-fold within 41 m. The correlation between nephelometer and gravimetric pollution measurements ranged 0.95–0.99. The presence of large, sudden but repeatable changes in air pollution, and high correlations between nephelometer and gravimetric measurements, indicate that mobile pollution monitoring devices provide a useful and accurate estimate of spatial variability. Estimated exposure for the town as a whole was 1.02 for the 6 months from April to September, 0.25 in October as heater use declines, and 0.12 in normal summer months. For comparison, published 25th, 50th and 75th percentiles of the distribution of nephelometer coefficients in Sydney were 0.15, 0.24 and 0.37, respectively. Thus annual exposure to PM2.5 pollution in Armidale from woodsmoke is more than double that from all sources in Sydney, a city of 4 million. Overseas estimates of 6% increased mortality for each additional 10 μg m −3 of PM2.5 suggest that wood heaters in Armidale may increase mortality in Armidale by about 7%, with estimated cost of about $4270 per woodheater per year. Alternative cheap and environmentally friendly methods of keeping houses warm in winter, such as solar heating, should therefore be developed.

Assessment of the Health Impacts of Particulates from the Redevelopment of Kings Cross

The Kings Cross/St. Pancras area has been a rail transport hub from Central London to the Midlands and North Eastern England since the middle of the nineteenth century and dust from the Kings Cross railway lands was even described by Charles Dickens. The Channel Tunnel high speed Rail Link (CTRL) is being constructed between 2001 and 2007 to connect continental Europe to Central London. The CTRL and associated development will help regenerate an area that is surrounded by deprived high density housing estates. London Borough of Camden has set up an extensive particulate monitoring programme to determine if there are any health impacts on local residents from emissions from the demolition and construction work. This article assesses the results from particulate measurements in 2003-2004 and compares this to baseline conditions before the redevelopment work began. The evidence suggests that although 2003 had higher than average pollution levels in the UK as a whole, even higher levels of particulates in the size range PM(10)-PM(2.5) (defined as PM(coarse)) were measured in Kings Cross. Due to the size of these particulates, they tend to be released from construction works rather than transport or secondary particulate sources. Concentrations in 2004 were lower than 2003, but this was primarily due to meteorological conditions. The paper also looks at the health of the local population and discusses whether these elevated levels are creating a problem and legally constitute a statutory nuisance. The Council continues to work with the contractors to try and ensure best practical means to minimise dust emissions and their effect on local residents.

Association Between Outdoor Air Pollution and Childhood Asthma Symptoms in Metropolitan Areas, United States

P-079 Introduction: Poor asthma outcomes have been linked to air pollution exposure in many studies focusing on local areas and/or short exposure duration. To assess the association between chronic outdoor air pollution exposure and asthma symptoms among children in metropolitan areas in the United States, air monitoring data from the U.S. Environmental Protection Agency (EPA) were merged with data from the National Health Interview Survey (NHIS). Methods: Annual average air pollutant levels for five criteria pollutants (particulate matter, ozone, sulfur dioxide, nitrogen dioxide, and carbon monoxide) were compiled by county for 2000–2003. The sample children in the study were ages 3–17 years residing in U.S. metropolitan areas for whom health conditions were reported in the 2001–2004 NHIS. Data for sample children were matched with exposure data for the previous 12 months when available for the county where they resided at the time of the NHIS interview. County-level pollutant values were ranked into quartiles. Logistic regression using survey sample weights was used to assess association between asthma outcomes (current asthma, recent asthma attack, and recent emergency room visit for asthma) and monitored air pollutant levels. Results: After adjusting for race/ethnicity, sex, parental education, poverty status, central city residence, and single parent household, the authors found that children living in the counties in the highest quartiles for all pollutants except carbon monoxide were generally more likely to have current asthma, a reported asthma attack in the previous 12 months, and a reported asthma emergency room visit in the previous 12 months than those residing in counties with pollution values ranked in the lower quartiles. For example, for children living in the highest quartile of pollution levels for particulate matter (aerodynamic diameter less than or equal to 2.5 micrometers), the adjusted odds ratio for current asthma was 1.53 (95% confidence interval [CI]: 1.06–2.23), for recent asthma attack 1.38 (95% CI: 0.95–2.01), and for asthma emergency room visit 1.73 (95% CI: 1.01–2.97). Conclusion: This analysis suggests that chronic exposure to air pollution in metropolitan areas throughout the U.S. may be associated with increased current asthma rates and ongoing asthma symptoms among children.

Association between maternal exposure to ambient air pollutants during pregnancy and fetal growth restriction

Previous research demonstrated consistent associations between ambient air pollution and emergency room visits, hospitalizations, and mortality. Effect of air pollution on perinatal outcomes has recently drawn more attention. We examined the association between intrauterine growth restriction (IUGR) among singleton term live births and sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), ozone (O3), and fine particles (PM2.5) present in ambient air in the Canadian cities of Calgary, Edmonton, and Montreal for the period 1985-2000. Multiple logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for IUGR, based on average daily levels of individual pollutants over each month and trimester of pregnancy after adjustment for maternal age, parity, infant gender, season, and city of residence. A 1 ppm increase in CO was associated with an increased risk of IUGR in the first (OR=1.18; 95% CI 1.14-1.23), second (OR=1.15; 95% CI 1.10-1.19) and third (OR=1.19; 95% CI 1.14-1.24) trimesters of pregnancy, respectively. A 20 ppb increase in NO2 (OR=1.16; 95% CI 1.09-1.24; OR=1.14; 95% CI 1.06--1.21; and OR=1.16; 95% CI 1.09-1.24 in the first, second, and third trimesters) and a 10 mug/m3 increase in PM2.5 (OR=1.07; 95% CI 1.03-1.10; OR=1.06; 95% CI 1.03-1.10; and OR=1.06; 95% CI 1.03-1.10) were also associated with an increased risk of IUGR. Consistent results were found when ORs were calculated by month rather than trimester of pregnancy. Our findings add to the emerging body of evidence that exposure to relatively low levels of ambient air pollutants in urban areas during pregnancy is associated with adverse effects on fetal growth.

Estimating the effect of air pollution from a coal-fired power station on the development of children's pulmonary function

Using geographical information systems (GIS) tools, the present study analyzed the association between children's lung function development and their long-term exposure to air pollution. The study covered the cohort of 1492 schoolchildren living in the vicinity of a major coal-fired power station in the Hadera sub-district of Israel. In 1996 and 1999, the children underwent subsequent pulmonary function tests (PFT) (forced vital capacity (FVC) and forced expiratory volume during the first second (FEV 1)), and the children's parents completed a detailed questionnaire on their health status and household characteristics. A negative association was found between changes in the results of PFT and the estimated individual levels of air pollution. A sensitivity test revealed a FEV 1 decline from −4.3% for the average pollution level to −10.2% for the high air pollution level. The results of a sensitivity test for FVC were found to be similar. Association with the reported health status was found to be insignificant. As we conclude, air pollution from a coal-fired power station, although not exceeding local pollution standards, had a negative effect on children's lung function development. As argued, previous studies carried out in the region failed to show the above association because they were based on zone approaches that assign average concentration levels of air pollutants to all individuals in each zone, leading to a misclassification bias of individual exposure.

Interval versions of statistical techniques with applications to environmental analysis, bioinformatics, and privacy in statistical databases

In many areas of science and engineering, it is desirable to estimate statistical characteristics (mean, variance, covariance, etc.) under interval uncertainty. For example, we may want to use the measured values x ( t ) of a pollution level in a lake at different moments of time to estimate the average pollution level; however, we do not know the exact values x ( t ) —e.g., if one of the measurement results is 0, this simply means that the actual (unknown) value of x ( t ) can be anywhere between 0 and the detection limit (DL). We must, therefore, modify the existing statistical algorithms to process such interval data. Such a modification is also necessary to process data from statistical databases, where, in order to maintain privacy, we only keep interval ranges instead of the actual numeric data (e.g., a salary range instead of the actual salary). Most resulting computational problems are NP-hard—which means, crudely speaking, that in general, no computationally efficient algorithm can solve all particular cases of the corresponding problem. In this paper, we overview practical situations in which computationally efficient algorithms exist: e.g., situations when measurements are very accurate, or when all the measurements are done with one (or few) instruments. As a case study, we consider a practical problem from bioinformatics: to discover the genetic difference between the cancer cells and the healthy cells, we must process the measurements results and find the concentrations c and h of a given gene in cancer and in healthy cells. This is a particular case of a general situation in which, to estimate states or parameters which are not directly accessible by measurements, we must solve a system of equations in which coefficients are only known with interval uncertainty. We show that in general, this problem is NP-hard, and we describe new efficient algorithms for solving this problem in practically important situations.

Birth Outcomes and Prenatal Exposure to Ozone, Carbon Monoxide, and Particulate Matter: Results from the Children’s Health Study

Exposures to ambient air pollutants have been associated with adverse birth outcomes. We investigated the effects of air pollutants on birth weight mediated by reduced fetal growth among term infants who were born in California during 1975–1987 and who participated in the Children’s Health Study. Birth certificates provided maternal reproductive history and residence location at birth. Sociodemographic factors and maternal smoking during pregnancy were collected by questionnaire. Monthly average air pollutant levels were interpolated from monitors to the ZIP code of maternal residence at childbirth. Results from linear mixed-effects regression models showed that a 12-ppb increase in 24-hr ozone averaged over the entire pregnancy was associated with 47.2 g lower birth weight [95% confidence interval (CI), 27.4–67.0 g], and this association was most robust for exposures during the second and third trimesters. A 1.4-ppm difference in first-trimester carbon monoxide exposure was associated with 21.7 g lower birth weight (95% CI, 1.1–42.3 g) and 20% increased risk of intrauterine growth retardation (95% CI, 1.0–1.4). First-trimester CO and third-trimester O3 exposures were associated with 20% increased risk of intrauterine growth retardation. A 20-μg/m3 difference in levels of particulate matter ≤ 10 μm in aerodynamic diameter (PM10) during the third trimester was associated with a 21.7-g lower birth weight (95% CI, 1.1–42.2 g), but this association was reduced and not significant after adjusting for O3. In summary, O3 exposure during the second and third trimesters and CO exposure during the first trimester were associated with reduced birth weight.

El proyecto Emecas: protocolo del estudio multicéntrico en España de los efectos a corto plazo de la contaminación atmosférica sobre la salud

The EMECAM Project demonstrated the short-term effect of air pollution on the death rate in 14 cities in Spain throughout the 1990-1995 period. The Spanish Multicentre Study on Health Effects of Air Pollution (EMECAS) is broadening these objectives by incorporating more recent data, information on hospital disease admissions and totaling 16 Spanish cities. This is an ecological time series study in which the response variables are the daily deaths and the emergency hospitalizations due to circulatory system diseases and respiratory diseases among the residents in each city. Pollutants analyses: suspended particles, SO2, NO2, CO and O3. Control variables: meteorological, calendar, seasonality and influenza trend and incidence. estimate of the association in each city by means of the construction of generalized additive Poisson regression models and metanalysis for obtaining combined estimators. The EMECAS Project began with the creation of three working groups (Exposure, Epidemiology and Analysis Methodology) which defined the protocol. The average levels of pollutants were below those established under the current regulations for sulfur dioxide, carbon monoxide and ozone. The NO2 and PM10 values were around those established under the regulations (40 mg/m3). This is the first study of the relationship between air pollution and disease rate among one group of Spanish cities. The pollution levels studied are moderate for some pollutants, although for others, especially NO2 and particles, these levels could entail a problem with regard to complying with the regulations in force.

Effects of Ambient Air Pollutants on Asthma Medication Use and Wheezing among Fourth-Grade School Children from 12 Southern California Communities Enrolled in The Children's Health Study

To investigate the effects of 12 monthly average air pollution levels on monthly prevalence of respiratory morbidity, the authors examined retrospective questionnaire data on 2034 4th-grade children from 12 Southern California communities that were enrolled in The Children's Health Study. Wheezing during the spring and summer months was associated with community levels of airborne particulate matter with a diameter < or = 10 microm (PM10) (odds ratio (OR) = 2.91; 95% confidence interval (CI) = 1.46-5.80), but was not associated with community levels of ozone, nitrogen dioxide, PM2.5 (diameter < or = 2.5), nitric acid, or formic acid. Logistic regression was performed on data stratified into two seasonal groups, spring/summer and fall/winter. Among asthmatics, the monthly prevalence of asthma medication use was associated with monthly levels of ozone, nitric acid, and acetic acid (OR = 1.80 [95%CI = 1.19-2.70]; OR = 1.80 [95%CI = 1.23-2.65]; OR = 1.57 [95% CI = 1.11-2.21]; respectively). Asthma medication use was more prevalent among children who spent more time outdoors--with consequential exposure to ozone--than among children who spent more time indoors (OR = 3.07 [95%CI = 1.61-5.86]; OR = 1.31 [95%CI = 0.47-2.71]; respectively). The authors concluded that monthly variations in some ambient air pollutants were associated with monthly respiratory morbidity among school children.

SHORT-TERM EFFECTS OF URBAN AIR POLLUTION ON MORTALITY IN SPAIN

ISEE-108 Introduction: The EMECAS multicenter study aims to evaluate the short-term effects of air pollution on mortality and hospital admissions in 16 Spanish cities. In this paper we present the combined results for total, respiratory and cardiovascular mortality. Methods: Daily mortality for all causes (ICD-9: 001–799), respiratory diseases (ICD-9: 460–519) and cardiovascular diseases (ICD-9: 390–459) was obtained for each city (1995–1999). Data for 24 hours daily levels of black smoke, total suspended particles (TSP), particles less than 10 mg (PM10), SO2 and NO2; 8 hours maximum moving average of CO and ozone; and 1 hour maximum of SO2, NO2, CO and ozone were collected from local Air Pollution Networks. Magnitude of association in each city was estimated using Generalized Additive Models (GAM) of Poisson, controlling for confusion and overdispersion. Covariables included were trend, temperature, humidity, barometric pressure, influenza, day of the week and unusual events. For each cause, lagged effects, up to three days, of each pollutant were examined. Data were analyzed using S-Plus GAM function with more stringent convergence criteria. Combined estimates were obtained under ’fixed effects’ model and, if heterogeneity, under ’random effects’ ones. For ozone the analyses were restricted to the warm period (May to October). Lastly, two-pollutants models are currently being performed to explore potential confounding for the other pollutants. Results: Average levels of pollutants were, in general, low to moderate (i.e., SO2: 15–73 mg/m3, PM10: 33–43 mg/m3, NO2: 23–79 mg/m3, ozone: 41–79 mg/m3). The more consistent lags were 0 (concurrent day) and 1. The combined estimates showed a significant association with total mortality for black smoke, TSP, SO2, CO and ozone. An increase of 10 mg/m3 in PM10 levels was associated with a 1.3% (95% CI: 0.2–2.5%) increase in respiratory mortality. The same increase in NO2 levels was associated with a 1.03% (95% CI: 0.4–1.7%), increase in respiratory mortality. Lastly, the combined estimates showed a significant increase of cardiovascular mortality associated with an increase of 10 mg/m3 in TSP levels (0.7%, 95% CI: 0.1–1.2%), black smoke levels (0.6%, 95% CI: 0.02–1.1%) and NO2 levels (0.6%, 95% CI: 0.2–0.9%). Results after performing the two-pollutants models will be presented as well, as modifications of the associations are expected. Discussion: A short-term association between increases in daily levels of urban air pollutants and daily mortality for all causes and respiratory and cardiovascular diseases has been found, with greater estimates for respiratory mortality.

WINTER AIR POLLUTION, COAL HOME HEATING, AND THE INCIDENCE OF PEDIATRICIAN-REPORTED LOWER RESPIRATORY ILLNESSES IN CHILDREN FROM BIRTH TO THREE YEARS

ISEE-444 Abstract: We undertook a cohort study to evaluate the relationship between ambient air pollution and early childhood respiratory morbidity in an eastern European country during the years 1994-1999. We examined the associations between winter (November through March) measures of fine- and coarse-fraction particulate matter (PM2.5 and PM10-2.5), sulfur dioxide (SO2), nitrogen oxides (NOX), and polycyclic aromatic hydrocarbons (PAHs) and the incidence of lower respiratory illnesses (LRI) in children from birth to three years of age. Study sites were located in two districts, one with high outdoor air pollution from power plants and coal home heating emissions, and the other an area with lower average outdoor air pollution. Morbidity and questionnaire information at three years was available for 452 children. All sick- and well-child visit diagnoses during the first three years of life were abstracted from pediatric records using ICD-10 classifications and categorized into broad illness groupings. Analyses reported here made use of an LRI grouping that included bronchitis and bronchiolitis (979 diagnoses) but excluded pneumonia (70 diagnoses). Multivariable analyses applied generalized estimating equation methods and adjusted for temperature, day of the week, district of residence, and year. In single-pollutant models, we found that LRI incidence increased with increasing concentrations of PM2.5, PM10-2.5, PAHs and NOX, but not with SO2. Though effect estimates were imprecise, an overall pattern emerged, with LRI incidence increasing with elevated air pollutant levels on the same day and the one or two days preceding diagnosis. For an interquartile range (IQR) increase in pollutant concentration, LRI incidence increased 12% (95% CI: −2.4%, 28%) for same-day PM2.5, 3.5% (95% CI: −1.6%, 8.9%) for same-day PM10-2.5, 8.1% (95% CI: −4.6%, 22%) for previous-day total PAHs, and 8.5% (95% CI: −6.1%, 25%) for three-day average NOX. Among children whose homes were heated primarily with coal, we observed much stronger pollutant-LRI associations. Per IQR-increase in three-day average pollutant levels, LRI incidence increased 84% (95% CI: 22%, 176%) for PM2.5, 24% (95% CI: 5.9%, 45%) for PM10-2.5, 33% (95% CI: 9.7%, 62%) for PAHs, and 22% (95% CI: −14%, 73%) for NOX. These findings underscore the importance of considering indoor and microenvironmental exposures in air pollution health studies conducted in a setting similar to this eastern European location, where local household emissions significantly impact outdoor pollutant concentrations.

Urban air pollution and mortality in a cohort of Norwegian men.

We investigated the association between total and cause-specific mortality and individual measures of long-term air pollution exposure in a cohort of Norwegian men followed from 1972-1973 through 1998. Data from a follow-up study on cardiovascular risk factors among 16,209 men 40-49 years of age living in Oslo, Norway, in 1972-1973 were linked with data from the Norwegian Death Register and with estimates of average yearly air pollution levels at the participants' home addresses from 1974 to 1998. Cox proportional-hazards regression was used to estimate associations between exposure and total and cause-specific mortality. During the follow-up time 4,227 men died from a disease corresponding to an ICD-9 (International Classification of Diseases, Revision 9) code < 800. Controlling for a number of potential confounders, the adjusted risk ratio for dying was 1.08 [95% confidence interval (CI), 1.06-1.11] for a 10- microg/m3 increase in average exposure to nitrogen oxides (NOx) at the home address from 1974 through 1978. Corresponding adjusted risk ratios for dying from a respiratory disease other than lung cancer were 1.16 (95% CI, 1.06-1.26); from lung cancer, 1.11 (95% CI, 1.03-1.19); from ischemic heart diseases, 1.08 (95% CI, 1.03-1.12); and from cerebrovascular diseases, 1.04 (95% CI, 0.94-1.15). The findings indicate that urban air pollution may increase the risk of dying. The effect seemed to be strongest for deaths from respiratory diseases other than lung cancer.

RISK OF CARDIAC ARRHYTHMIAS AMONG IMPLANTED CARDIOVERTER DEFIBRILLATOR PATIENTS ASSOCIATED WITH SIX-HOUR AIR POLLUTION EXPOSURES

In previous analyses risk of cardiac arrhythmias in cardiac patients with implanted cardioverter defibrillators (ICD) was associated with average air pollution (PM2.5 and SO2) levels on the same day. In this analysis we investigated how the risk of arrhythmias varies during the day and associations with shorter air pollution exposures. We abstracted data of 86 New England Medical Center patients with ICD devices living in the Boston metropolitan area between June 1995 and June 2002. Date and time of ICD recorded arrhythmia and therapeutic interventions were downloaded during the patients' regular clinical follow-up (on average every 3 months). Electrocardiograms for each arrhythmia were reviewed by an electrophysiologist and classified as ventricular or supra-ventricular. We divided each day into night (0–6 AM), morning (6 AM–12 PM), afternoon (12–6 PM), and evening (6 PM-12 AM). A subject-specific episode was defined as one or more ICD detected arrhythmias in that period. Hourly fine particle and gaseous pollutant and meteorological data for the Boston area were averaged over the same 6 hour periods. Risk of arrhythmias associated with air pollution was estimated by logistic regression with adjustment for season, temperature, relative humidity, day of the week, and time period within the day. 44 patients with a mean follow-up time of 3.7 years had a total of 489 ventricular cardiac episodes. The episodes had a weak diurnal pattern with 25% 29%, 27% and 19% in the morning afternoon, evening, and night periods respectively. The risk of a ventricular arrhythmia was associated with PM2.5, SO2., NO2, and CO during the same six-hour period. (PM2.5: OR = 1.17, 95% CI 1.04,1.32 for each inter-quartile range increase [8.8 ug/m3], SO2: OR = 1.20, 95% CI 1.09, 1.32 for 4.6 ppb, NO2: OR = 1.24, 95% CI 1.08,1.41 for 4.6 ppb, CO: OR = 1.25, 95% CI 1.08,1.33 for 564 ppb). Associations between arrhythmias and air pollution during time periods 6 to 30 hours back were slightly weaker. Larger effects were found for men compared to women, and for whites compared to non-whites. These results are comparable in magnitude to previously reported associations of ICD detected arrhythmias with daily air pollution episodes, but suggest that the short air pollution episodes (less than six hours) may trigger cardiac arrhythmias in these particularly susceptible populations. This study was funded by the Health Effects Institute (98-14), and the National Institute of Environmental Health Sciences (ES-00002 and ES-09825).

Spatial Regression Models for Large-Cohort Studies Linking Community Air Pollution and Health

Cohort study designs are often used to assess the association between community-based ambient air pollution concentrations and health outcomes, such as mortality, development and prevalence of disease, and pulmonary function. Typically, a large number of subjects are enrolled in the study in each of a small number of communities. Fixed-site monitors are used to determine long-term exposure to ambient pollution. The association between community average pollution levels and health is determined after controlling for risk factors of the health outcome measured at the individual level (i.e., smoking). We present a new spatial regression model linking spatial variation in ambient air pollution to health. Health outcomes can be measured as continuous variables (pulmonary function), binary variables (prevalence of disease), or time-to-event data (survival or development of disease). The model incorporates risk factors measured at the individual level, such as smoking, and at the community level, such as air pollution. We demonstrate that the spatial autocorrelation in community health outcomes, an indication of not fully characterizing potentially confounding risk factors to the air pollution--health association, can be accounted for through the inclusion of location in the deterministic component of the model assessing the effects of air pollution on health or through a distance-decay spatial autocorrelation function in the stochastic component of the model, or both. We present a statistical approach that can be implemented for very large cohort studies. Our methods are illustrated with an analysis of the American Cancer Society cohort to determine whether the prevalence of heart disease is associated with concentrations of sulfate particles. From a statistical point of view, it appears that a location surface in the deterministic component of the model was preferred to a distance-decay autocorrelation structure in the model's stochastic component.

Exposure to particulate matter, volatile organic compounds, and other air pollutants inside patrol cars.

People driving in a vehicle might receive an enhanced dose of mobile source pollutants that are considered a potential risk for cardiovascular diseases. The exposure to components of air pollution in highway patrol vehicles, at an ambient, and a roadside location was determined during 25 work shifts (3 p.m. to midnight) in the autumn of 2001, each day with two cars. A global positioning system and a diary provided location and activity information. Average pollutant levels inside the cars were low compared to ambient air quality standards: carbon monoxide 2.7 ppm, nitrogen dioxide 41.7 microg/m3, ozone 11.7 ppb, particulate matter smaller 2.5 microm (PM2.5) 24 microg/m3. Volatile organic compounds inside the cars were in the ppb-range and showed the fingerprint of gasoline. PM2.5 was 24% lower than ambient and roadside levels, probably due to depositions associated with the recirculating air conditioning. Levels of carbon monoxide, aldehydes, hydrocarbons, and some metals (Al, Ca, Ti, V, Cr, Mn, Fe, Cu, and Sr) were highest in the cars, and roadside levels were higher than ambient levels. Elevated pollutant levels were related to locations with high traffic volumes. Our results point to combustion engine emissions from other vehicles as important sources of air pollutants inside the car.

Validation of the improved AEROPOL model against the Copenhagen data set

The improved Gaussian dispersion model AEROPOL (University of Tartu, Estonia) is validated against the Copenhagen air pollution dispersion dataset belonging to the Model Validation Kit of the Initiative on 'Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes'. Model updates include the application of (1) surface heat flux instead of indirect indicators of surface layer stability and (2) two-level wind data instead of one (10 m) level. Validation results show a fair agreement of modelled and measured concentrations. In comparison with several models validated earlier, the scatter of modelled versus measured data is moderate, but a systematic deviation is small. Thus, the AEROPOL model is recommended for urban dispersion calculations in nearly neutral conditions. Best results are expected for long-term average pollution levels.

A new sensitive test based on yeast cells for studying environmental pollution

Different tests based on yeast cells were developed for determination of mutagenic/carcinogenic action; however, they all showed lower sensitivity compared to bacterial tests, the main reason for this being the limited permeability of yeast cells. We found that general permeability of Saccharomyces cerevisiae cells can be increased by mutation and on this basis we developed a more sensitive test. The aim of this study was to prove the applicability of our test, called D7ts1, in environmental studies. Soil, water and air samples were taken during 1998 from regions in Bulgaria with declared low, average or high pollution levels and investigated for presence of mutagenic/carcinogenic activities in the bacterial test of Ames, the yeast D7 test of Zimmermann and our new D7ts1 test. Results obtained evidenced the following conclusions: (1) the usage of D7ts1 test instead of D7 test permits a clearer measurement of positive samples and detects mutagenic/carcinogenic activities undetectable by D7 test; (2) all samples with positive Ames test were positive in the D7ts1 test; however, some samples, clearly positive in the D7ts1, were negative in the Ames test; therefore, the simultaneous usage of D7ts1 and Ames tests in environmental studies is advantageous because it detects dangers for the human health activities to which bacterial cells do not respond; and (3) regions in Bulgaria declared clean were found to be polluted; particularly troubled are the whole-year positive data in the three tests for air samples from a ‘clean’ region.

Indoor/outdoor air quality correlation and questionnaire survey at two staff quarters in Hong Kong

The indoor and outdoor air quality at two staff quarters of the Hong Kong Polytechnic University (HKPU) were investigated during January and February 1996. The air pollutants measured were NO k, NO, NO 2, SO 2, CO, and O 3. All indoor and outdoor pollutant concentrations did not exceed the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) and the National Ambient Air Quality Standard (NAAQS) standards. Significant differences in the pollutant concentrations were observed for samples collected on weekdays when compared with those collected on Sundays (P-value < 0.05). The average indoor and outdoor pollutant levels at the Tsim Sha Tsui East (TSTE) quarter were higher than those at the Shatin (ST) quarter except for O 3. All O 3 levels were found to be lower at the TSTE quarter than at the ST quarter, and TSTE/ST O 3 concentration ratios were 0.72 for the outdoors and 0.79 for the indoors, respectively. Lower O 3 levels at the TSTE quarter were due to the NO titration reaction. All indoor pollutant levels were lower than those at the outdoors except for CO, which indicates the presence of indoor CO sources. A questionnaire survey was used to study the relationship between prevalence of illnesses and risk factors.

DNA adducts in human placenta as related to air pollution and to GSTM1 genotype

DNA adducts in human placenta have been studied in relation to metabolic genotype for glutathione S-transferase M1 (GSTM1) in 98 mothers living in two regions with a different annual average air pollution levels: Northern Bohemia – the district of Teplice as polluted industrial area (mines, brown coal power plants) and Southern Bohemia – the district of Prachatice as agricultural area without heavy industry. Forty-nine placenta samples (25 from the Teplice district and 24 from the Prachatice district) from non-smoking mothers with the date of delivery in the summer period and 49 placenta samples (25 from the Teplice district and 24 from Prachatice district) from mothers with the date of delivery in the winter period were analysed. The total DNA adduct levels were calculated as the sum of adducts in the diagonal radioactive zone (DRZ) and one distinct spot outside of the DRZ (termed X), which was detected in almost all placenta samples. We found total DNA adduct levels of 1.40±0.87 (0.04–3.65) and 1.04±0.63 (0.11–3.08) adducts per 10 8 nucleotides for the Teplice and Prachatice districts, respectively. The significant difference between both districts in placental DNA adduct levels was found for the winter sampling period only (1.49 vs. 0.96 adducts per 10 8 nucleotides; p=0.023). No seasonal variation was observed for DNA adduct levels in the overall population studied. A positive GSTM1 genotype was detected in 51 subjects, while GSTM1-null genotype was found in 47 subjects. Higher DNA adduct levels were detected in a group with GSTM1-null genotype ( p=0.009). This finding seems more significant for subjects in the Teplice district ( p=0.047) than for those in the Prachatice district ( p=0.092). Significant district and seasonal differences were found in subgroups carrying the GSTM1-null genotype. DNA adduct levels in placentas of mothers with GSTM1-null genotype living in the polluted district of Teplice were higher than those in Prachatice ( p=0.050); also the adduct levels in placentas sampled in the summer period were higher than those sampled in the winter period ( p=0.011). Our results indicate that simultaneous analysis of DNA adducts and metabolic genotypes could emphasize the use of DNA adduct measurements, particularly in the case of the environmental exposure when the total doses of genotoxic pollutants are very low.

Influence of GSTM1 and NAT2 genotypes on placental DNA adducts in an environmentally exposed population

The placenta bulky DNA adducts have been studied in relation to metabolic genotypes for glutathione S-transferase M1 (GSTM1) and N-acetyl transferase 2 (NAT2) in 158 mothers (113 nonsmokers and 45 smokers) living in two regions with different annual average air pollution levels of sulphur dioxide, nitrogen oxides, particulate matter < 10 microns, and polycyclic aromatic hydrocarbons. One region was the district of Teplice as the polluted industrial region with mines and brown coal power plants, and the other was the district of Prachatice, an agricultural region without heavy industry. DNA adduct levels were determined by using a butanol extraction enrichment procedure of 32P-postlabeling. GSTM1 and NAT2 genotypes were studied by using polymerase chain reaction. The total DNA adduct levels included a diagonal radioactive zone (DRZ) and one distinct spot outside DRZ (termed X), which was detected in almost all placenta samples and correlated with DRZ (r = .682; P < .001). We found the total DNA adduct levels 2.12 +/- 1.46 (0.04-7.70) and 1.48 +/- 1.09 (0.11-4.98) adducts per 10(8) nucleotides for Teplice and Prachatice districts, respectively, indicating significant differences between both regions studied (P = .004). Elevated DNA adduct levels were found in smoking mothers (10 or more cigarettes per day) by comparison with nonsmoking mothers (3.21 +/- 1.39 versus 1.32 +/- 0.88 adducts per 10(8) nucleotides; P < .001). Placental DNA adduct levels in smokers correlated with cotinine measured in plasma (r = .432; P = .003). This relation indicates that cigarette smoking could be predominantly responsible for DNA adduct formation in placentas of smoking mothers. DNA adduct levels were evaluated separately for non-smokers (1.50 +/- 1.00 vs. 1.09 +/- 0.66 adducts/10(8) nucleotides for the Teplice and Prachatice districts, respectively; P = .046) and smokers (3.35 +/- 1.47 vs. 2.91 +/- 1.20 adducts/10(8) nucleotides for Teplice and Prachatice districts, respectively; P = .384) to exclude the effect of active cigarette smoking on the district variation. These findings indicate that the effect of the environmental pollution in cigarette smokers is practically overlapped by tobacco exposure. No seasonal variation was observed for DNA adduct levels in the overall population studied and no relation between total DNA adduct levels in placenta and levels of vitamins A, C, and E in venous and cord blood was found. A positive GSTM1 genotype was detected in 78 subjects, while negative GSTM1 genotype was found in 80 subjects. Higher DNA adduct levels were detected in the group with GSTM1-negative genotype by comparison with GSTM1-positive genotype (2.05 +/- 1.30 vs. 1.66 +/- 1.39 adducts/10(8) nucleotides; P = .018). This finding is more pronounced in the Teplice district (2.33 +/- 1.36 vs. 1.88 +/- 1.56 adducts/10(8) nucleotides; P = .053) than for the Prachatice district (1.61 +/- 1.09 vs. 1.36 +/- 1.10 adducts/10(8) nucleotides; P = .248) and for nonsmokers (1.45 +/- 0.82 vs. 1.18 +/- 0.93 adducts/10(8) nucleotides; P = .029) more than for smokers (3.45 +/- 1.14 vs. 2.95 +/- 1.62 adducts/10(8) nucleotides; P = .085). Significant district and seasonal differences were found in subgroups with GSTM1-negative genotype. DNA adduct levels in placentas of the GSTM1-negative subgroup were higher in mothers living in the polluted district of Teplice than in Prachatice (P = .012). The adduct levels in placentas sampled in the summer period were higher than in the winter period in the GSTM1-negative population (P = .006). No effect of the NAT2 genotype on DNA adduct levels was observed.