Indoor air quality modeling: Compartmental approach with reactive chemistry

Data on indoor/outdoor pollutant and tracer concentrations were collected during different periods in 1981 at a residence in Newton, MA. Special studies within the kitchen were conducted to determine the vertical and horizontal variability of pollutant and tracer gas concentrations. A reactive chemistry model incorporating simplified NO_x chemistry was developed to simulate pollutant concentrations indoors. Multicompartmental mathematical modeling tools were also developed and tested to estimate efficiently the effective, emission, ventilation, and removal rates, as well as the intercompartmental pollutant exchange coefficients. Model studies utilizing two- and three-compartment systems and tracer measurements proved that the dynamics of pollutant mixing inside a kitchen is not only complex but may be quite important in controlling spatial and temporal variability of reactive species. Further monitoring and modeling studies to investigate the critical aspects of the short-term dynamics of the reactive pollutants inside homes with gas cooking stoves are recommended.     

Comparison of indoor and outdoor air quality at two staff quarters in Hong Kong

The indoor and outdoor air quality of two staff quarters of Hong Kong Polytechnic University at Tsim Sha Tsui East (TSTE) and Shatin (ST) were investigated. The air sampling was carried out in winter for about two months starting from January to February of 1996. Fifteen flats from each staff quarter were randomly selected for indoor/outdoor air pollutant measurements. The pollutants measured were NO_x, NO, NO₂, SO₂, CO, and O₃. The variations of pollutant concentrations between indoor and outdoor air were investigated on weekday mornings, weekday evenings, weekend mornings, and weekend evenings. All indoor/outdoor pollutant concentrations measured did not exceed the ASHRAE/NAAQS standard. The carbon monoxide concentrations indoors were systemically higher than those outdoors at the TSTE and the ST quarters, both on weekdays and Sunday, which indicates there are CO sources indoors. Except for CO, the indoor levels of other pollutants (NO_x, NO, NO₂, SO₂, and O₃) are lower than those outdoors. There was a significant correlation (P < 0.05) between indoor and outdoor concentrations for SO₂ and O₃ at both the TSTE and the ST quarters. Except for O₃, the mean concentrations of all the pollutants in the TSTE quarters, both indoor and outdoor, were higher than that of the ST quarters in all sampling periods. All indoor and outdoor O₃ levels were lower at the TSTE quarters than those at the ST quarters. The O₃ ratios of TSTE/ST were 0.72 outdoor and 0.79 indoor. This can be explained by the NO titration reaction through NO conversion to NO₂.     

Measurements and analysis of criteria pollutants in New Delhi, India

Ambient concentrations of carbon monoxide (CO), nitrogen oxides (NOx), sulfur dioxide (SO2), and total suspended particulates (TSP) were measured from January 1997 to November 1998 in the center of downtown [the Income Tax Office (ITO) located on B.S.G. Marg] New Delhi, India. The data consist of 24-h averages of SO2, NOx, and TSP as well as 8 and 24-h averages of CO. The measurements were made in an effort to characterize air pollution in the urban environment of New Delhi and assist in the development of an air quality index. The yearly average CO, NOx, SO2, and TSP concentrations for 1997 and 1998 were found to be 4810+/-2287 and 5772+/-2116 microg/m3, 83+/-35 and 64+/-22 microg/m3, 20+/-8 and 23+/-7 microg/m3, and 409+/-110 and 365+/-100 microg/m3, respectively. In general, the maximum CO, SO2, NOx, and TSP values occurred during the winter with minimum values occurring during the summer, which can be attributed to a combination of meteorological conditions and photochemical activity in the region. The ratio of CO/NOx (approximately 50) indicates that mobile sources are the predominant contributors for these two compounds in the urban air pollution problem in New Delhi. The ratio of SO2/NOx (approximately 0.6) indicates that point sources are contributing to SO2 pollution in the city. The averaged background CO concentrations in New Delhi were also calculated (approximately 1939 microg/m3) which exceed those for Eastern USA (approximately 500 microg/m3). Further, all measured concentrations exceeded the US National Ambient Air Quality Standards (NAAQS) except for SO2. TSP was identified as exceeding the standard on the most frequent basis.     

Studies on indoor air quality in Egypt

Indoor air quality was examined for some gaseous pollutants and particulate matters. In a public library, the indoor/outdoor ratio of gaseous pollutants were found to be dependent on their reactivity, also on the outdoor concentrations and weather conditions. This ratio was 0.6 for SO₂,and 1.3 for CO. The indoor/outdoor ratio of carbon monoxide was found to increase at the higher floors of the same building. Concentrations of indoor particulates was found to be influenced by the outdoor concentrations and the particle size. Analysis indicated that indoor suspended dust contained a significant high concentration of lead as compared with outdoor values. Indoor sources were found to pollute the premises of fossil-fuel equipped homes, thus having carbon monoxide concentrations more than the recognized threshold limit value for industry.     

Spatial variation of carbon monoxide and oxides of nitrogen concentrations inside residences

A spatial comparison of pollutant concentrations within the residential environment is undertaken, comparing pollutant concentrations from three indoor sampling locations (zones). The indoor air quality base was obtained from sampling the indoor air of 12 residential sites and two office buildings in the metropolitan Boston area. Each residential site was monitored continuously for two weeks, and data were reduced into hourly averages. Interzonal comparisons of the mean of hourly averages, 24-h averages, and daily maximum hourly concentrations were made at all sites. Linear regressions were computed between daily maximum hourly concentrations and mean 24-h concentrations of NO, NO₂, and CO for kitchens to determine whether maximum hourly concentrations could be predicted from the 24-h concentration. These pollutants show interzonal statistical differences in residences with gas-fired cooking facilities but not in residences with electric cooking facilities. It was determined that, while one indoor sampling zone is not sufficient to specify indoor pollutant concentration maxima in residences having indoor sources of pollution, the daily mean of hourly pollutant concentrations obtained from one indoor zone can adequately describe the indoor environment. In addition, the maximum indoor hourly concentration for NO, NO₂, and CO can be estimated for residences with all electric facilities, by using the mean 24-h concentration. The reliability of similar estimates for NO, NO₂, and CO in residences with unvented gas appliances is reduced because of substantially more scatter in the paired data point, particularly at higher pollutant concentrations.     

Comparative overview of indoor air quality in Antwerp, Belgium

This comprehensive study, a first in Belgium, aimed at characterizing the residential and school indoor air quality of subgroups that took part in the European Community Respiratory Health Survey and the International Study of Asthma and Allergy in Childhood [Masoli M, Fabian D, Holt S, Beasley R. Global Burden of Asthma, Medical Research Institute of New Zealand, University of Southampton; 2004.] questionnaire-based asthma and related illnesses studies. The principal aim was to perform a base-line study to assess the indoor air quality in Antwerp in terms of various gaseous and particulate pollutants. Secondly, it aimed to establish correlations between these pollutants investigated, the pollutant levels in the indoor and outdoor micro-environments, findings of the previous questionnaire-based studies and an epidemiological study which ran in conjunction with this study. Lastly, these results were compared and evaluated with current indoor and ambient guidelines in various countries This paper presents selected results on PM1, PM2.5 and PM10 mass concentrations and elemental C estimates as black smoke, as well as gaseous NO(2), SO(2), O(3) and BTEX concentrations of 18 residences and 27 schools. These are related to current guidelines of Flanders, Germany, Norway, China and Canada and evaluated with reference to selected similar studies. It was found that indoor sources such as tobacco smoking and carpets, the latter causing re-suspension of dust, are responsible for elevated indoor respirable particulate matter and place school children and residents at risk. Both PM2.5 and PM10 equalled or exceeded the current guidelines adopted by Flanders, noting that 12-h and 24-h PM2.5 were compared with an annual limit value. Indoor and ambient NO(2) concentrations in the school campaign were higher than the annual EU ambient norm. The other studied pollutant levels were below the current guidelines.     

Genotoxicity of syrian hamster lung cells treated in vivo with diesel exhaust particulates

Polycyclic aromatic hydrocarbons extracted and concentrated from diesel exhaust particulates have been shown to be mutagenic and carcinogenic, but attempts to induce pulmonary tumors through chronic inhalation of diesel exhaust by experimental animals have failed. We have attempted to resolve this incongruity by measuring chromosomal damage in lung tissue of chronically exposed hamsters, using the highly sensitive test for genotoxic chemical agents, sister chromatid exchange (SCE) analysis. To determine the degree of responsiveness of the test system to both diesel exhaust particulates and benzo(a)pyrene (BaP), these agents were instilled intratracheally into anesthetized hamsters as suspensions in 0.25 ml volumes of Hank's balanced salt solution (HBSS). Lung tissues from these animals were subsequently cultured in vitro and chromosomes from the resulting cell divisions were scored for exchanges of chromatin between sister chromatids. Control animals, treated weekly with 0.25 ml of BSS for 10 weeks, showed an average value of 12 SCE's per cell, while animals treated weekly with 200 ng BaP over a 10-week period showed an average of 17 SCE's per cell. HBSS, given as a single treatment, also produced an average of 12 SCE's per cell in control animals, but animals treated with a single instillation of 12.5 μg BaP showed an average SCE value of 19. These data confirmed that the procarcinogen BaP can be metabolically activated by lung cells in vivo and also demonstrated the efficacy of using this technical approach to study the effect of chemical mutagens that enter the lungs. Diesel exhaust particulates, administered in a range from 0 to 20 mg per hamster over a 24 h exposure period, produced a linear SCE dose-response ranging from 12 to 26 SCE's per metaphase. This curve suggested that a concentration of 3 mg of diesel particulates per hamster would not produce a statistically significant increase in SCE's above control values. One group of 8 hamsters, chronically exposed to diesel exhaust particulates for 3 months showed an average of 12 SCE's per cell. This was equivalent to a set of 5 control animals which also showed an average of 12 SCE's per cell. Although the scope of this study was limited, the data demonstrated that diesel exhaust particulates can induce genotoxic damage but a 3-month exposure to 6 mg/m³ of diesel exhaust particulates was insufficient to produce measurable mutagenic changes in lung cells. This negative response is consistent with the results from other studies in which similar exposures failed to produce pulmonary tumors.     

Pollutant emission rates from indoor combustion appliances and sidestream cigarette smoke

Particulate and gaseous emissions from indoor combustion appliances and smoking can elevate the indoor concentrations of various pollutants. Indoor pollutant concentrations resulting from operating one of several combustion appliances, or from sidestream tobacco smoke, were measured in a 27-m³ environmental chamber under varying ventilation rates. The combustion appliances investigated were gas-fired cooking stoves, unvented kerosene-fired space heaters, and unvented natural-gas-fired space heaters. Results showed elevated levels of carbon dioxide, carbon monoxide, nitric oxide, nitrogen dioxide, formaldehyde, and suspended particles from one or more of the pollutant sources investigated. Our findings suggest that, of the sources examined in this study, nitrogen dioxide from combustion appliances and particles from sidestream cigarette smoke are the most serious contaminants of indoor air, if we use existing standards and guidelines as the criteria. An emission rate model was used to quantify the strengths of the pollutant sources, which are reported in terms of the mass of pollutant emitted per energy unit of fuel consumed (in the case of gas and kerosene appliances) and per mass of tobacco combusted (in the case of smoking).     

Benzo[a]pyrene metabolism in mice exposed to diesel exhaust: I. Uptake and distribution

In this study we examined the effect of diesel exhaust (DE) exposure on the disposition of a typical polycyclic aromatic hydrocarbon. DE-exposed and nonexposed A/Jax mice were divided into three groups and each mouse instilled intratracheally with benzo[a]pyrene (BaP). One group (A) received ¹⁴C-BaP, and at intervals of 2, 24, and 168 h, three mice from the group were killed and quick frozen for whole body autoradiography. Sagittal sections were cut at 0.5 mm intervals and autoradiograms prepared. Adjacent sections were studied so that radioactive areas were matched to specific organs. The second group (B) received ³H-BaP and at 2, 24, and 168 h these mice were killed. Livers, lungs, and testes were weighed and frozen. From these tissues metabolites were analyzed; these data are reported in the next paper. Histofluorescent examination of tissues from mice instilled with nonradioactive BaP (group C) confirmed that BaP was present in the lung. The autoradiography data are the basis for elucidating the BaP distribution in the mouse. Within 2 h after instillation radioactivity was detected in the entire animal, with most in lungs, liver, and GI tract. By 24 h after instillation considerable radioactivity had redistributed to the GI tract. At 168 h after instillation only a trace of label was found in the GI mucosa.     

Benzo[a]pyrene metabolism in mice exposed to diesel exhaust: II. Metabolism and excretion

In this study we examined the effect of diesel exhaust (DE) exposure on in vivo metabolism of benzo[a]pyrene (BaP). DE-exposed and unexposed A/Jax mice of group B were instilled intratracheally with ³H-BaP. At each time point of 2, 24, and 168 h after instillation five mice were killed and the liver, lungs, and testes were removed and frozen. Aliquots of the organs were homogenized in 2 ml water and each received 3 volumes of cold ethanol. Radioactivity in supernatant and precipitate was measured. The supernatant extracts were subjected to HPLC analysis on ALOX-T and on Zorbax ODS. The ALOX-T method was a modification of Autrup's procedure for conjugate assay (Biochem. Pharmacol.28, 1727, 1979). Fractions were (a) free BaP; (b) nonconjugated primary metabolites; (c) sulfate conjugates; (d) glucuronides, glutathiones, and other conjugates. By 2 h after instillation primary metabolites were found in liver and lung, but very little was conjugated. The unconjugated BaP was mainly in the form of free BaP and phenolic metabolite(s). The lungs of DE-exposed mice had less capacity to dispose of “bound” BaP 1 week after instillation.     

Personal exposure monitoring to nitrogen dioxide

Measurement of personal exposure to nitrogen dioxide for short and long term was made with a sensitive NO₂ passive sampler by volunteer housewives and office workers in different seasons. These measurements were compared with the simultaneous measurement of outdoor and indoor concentration of the participants. A common result over all the measurements is the potential effect of using an unvented space heater to increase personal exposure. Mean personal exposure and indoor concentration are higher than outdoor levels elevated by the samples exposed to pollutant produced from the heater. Without an NO₂ source indoors, the mean outdoor concentrations are always highest among the data of measurement. A time-weighted indoor/outdoor activity model gives modestly improved estimates of personal exposure over those predicted from measured indoor concentrations alone.     

Wintertime indoor air levels of PM10, PM2.5 and PM1 at public places and their contributions to TSP

From 26 October 2002 to 8 March 2003, particulate matter (PM) concentrations (total suspended particles [TSP], PM10, PM2.5 and PM1) were measured at 49 public places representing different environments in the urban area of Beijing. The objectives of this study were (1) to characterize the indoor PM concentrations in public places, (2) to evaluate the potential indoor sources and (3) to investigate the contribution of PM10 to TSP and the contributions of PM2.5 and PM1 to PM10. Additionally, The indoor and outdoor particle concentrations in the same type of indoor environment were employed to investigate the I/O level, and comparison was made between I/O levels in different types of indoor environment. Construction activities and traffic condition were the major outdoor sources to influence the indoor particle levels. The contribution of PM10 to TSP was even up to 68.8%, while the contributions of PM2.5 and PM1 to PM10 were not as much as that of PM10 to TSP.     

Carbon monoxide levels in microenvironment types of four U.S. cities

Portable monitors were used to measure time-averaged personal exposure (10–30 min) to carbon monoxide. Data were collected from January through March 1981 in four cities where ambient carbon monoxide levels have been reported in excess of National Ambient Air Quality Standards: Stamford, CT; Los Angeles, CA; Phoenix, AZ; and Denver, CO. In each city, personal exposure were measured in three common microenvironment types (indoor, commuting, and residential driving) near fixed stations monitoring ambient levels of carbon monoxide. Measurements recorded at urban-residential fixed monitoring stations (excluding one station in Stamford) underrepresented the time-weighted mean of commuting and residential driving exposures by factors of 0.4 to 0.7. The highest mean commuting and residential driving exposures were found in Los Angeles (16.1 and 7.6 μL/L, respectively). Fixed monitoring stations in Los Angeles, Phoenix, and one station in Stamford overrepresented the time-weighted mean of indoor exposures by factors of 1.1 to 1.3. However, in Denver and another station in Stamford, urban stations underrepresented the mean of indoor exposures by factors of 0.4 to 0.8. The highest mean indoor exposure, 5.9 μL/L, was in Denver. In all four cities, regressing personal exposures on concurrent fixed-site concentrations for all recorded values and for values recorded during 8-h NAAQS exceedance time periods revealed no conclusive linear relationships.     

Seasonal assessment of environmental tobacco smoke and respirable suspended particle exposures for nonsmokers in Bremen using personal monitoring

The study was designed to determine seasonal differences in personal exposures to respirable suspended particles (RSP) and environmental tobacco smoke (ETS) for nonsmokers in Bremen, Germany. The subjects were office workers, either living and working in smoking locations or living and working in nonsmoking locations. One hundred and twenty four randomly selected nonsmoking subjects collected air samples close to their breathing zone by wearing personal monitors for 24 h or, in some cases, for 7-day periods during the winter of 1999. The investigation was repeated in the summer with 126 subjects, comprised of as many of the studied winter population (89 subjects) as possible. Saliva cotinine analyses were undertaken to verify the nonsmoking status of the subjects. Subjects wore one personal monitor while at work and one while away from the workplace on weekdays, and a third monitor at the weekend. Collected air samples were analysed for RSP, nicotine, 3-ethenylpyridine (3-EP) and ETS particles. The latter were estimated using ultraviolet absorbance (UVPM), fluorescence (FPM) and solanesol (SolPM) measurements. ETS exposure was consistently higher in the winter than in the summer, this pattern being particularly evident for subjects both living and working with smokers. The highest median 24-h time weighted average (TWA) concentrations of ETS particles (SolPM, 25 microg m(-3)) and nicotine (1.3 microg m(-3)) were recorded for subjects performing weekday monitoring during the winter. These were significantly higher than equivalent levels of ETS particles (SolPM, 2.4 microg m(-3)) and nicotine (0.26 microg m(-3)) determined during the summer. There were no appreciable differences between winter and summer percent workplace contributions to median TWA ETS particle and nicotine weekday concentrations, the workplace in Bremen, in general, contributing between 35% and 61% of reported median concentrations. Workers, on average, spent one-third of their time at work during a weekday, indicating that concentrations were either comparable or higher in the workplace than in the home and other locations outside the workplace. Median 24-h weekend ETS particle and nicotine concentrations for smoking locations were not significantly different from equivalent weekday levels during the winter, but were significantly lower during the summer. Based upon median 24-h TWA SolPM and nicotine concentrations for the winter, extrapolated to 1 year's ETS exposure, those subjects both living and working in smoking locations (the most highly exposed group) would potentially inhale 13 cigarette equivalents/year (CEs/y). However, based on a similar extrapolation of summer measurements, the same group of subjects would potentially inhale between 1.3 and 1.9 CEs/y. The most highly exposed subjects in this study, based upon 90th percentile concentrations for those both living and working in smoking locations during the winter, would potentially inhale up to 67 CEs/y in the winter and up to 22 CEs/y in the summer. This clearly demonstrates that seasonal effects should be taken into account in the design and interpretation of ETS exposure studies. Air sampling over a 7-day period was shown to be technically feasible, and subsequent RSP, ETS particle and nicotine levels determined by 7-day monitoring were not found to be significantly different from equivalent levels determined by 24-h monitoring. However, the longer sampling period resulted in the collection of an increased quantity of analytes, which improved the limits of quantitation (LOQ) and allowed a more accurate determination of low level ETS exposure. This was reflected by a reduced percentage of data falling below the LOQ for 7-day monitoring compared with 24-h monitoring. The use of a liquid chromatographic method with tandem mass spectrometric detection for saliva cotinine measurement afforded a greatly improved LOQ and greater accuracy at low concentrations compared with the radioimmunoassay (RIA) method used in previous studies by these authors. In this study, 17 subjects out of 180 tested (9.4%) were found to have saliva cotinine levels exceeding the selected threshold of 25 ng ml(-1) used to discriminate between smokers and nonsmokers.     

DNA-binding studies with diesel exhaust particle extract

This study examines whether chemical components from diesel exhaust particulates react with DNA to form covalently bound adducts. Experiments in this report describe the in vitro reaction of purified DNA with a dichloromethane extract of diesel exhaust particulates in the absence or presence of enzyme activation by rat liver microsomes. The reactivity of the particle extract was compared to that of benzo[a]pyrene metabolites using low temperature fluorescence techniques which detect small quantities of polycyclic aromatic compounds bound to DNA. Incubation of DNA with the particle extract in the presence of microsomal enzymes produced no detectable fluorescent adducts in contrast to model experiments using benzo[a]pyrene. However, addition of the particle extract to incubation mixtures containing benzo[a]pyrene markedly decreased formation of benzo[a]pyrene-DNA adducts because the particle extract inhibits microsomal enzymes which activate benzo[a]pyrene and other polycyclic aromatic hydrocarbons. In the absence of microsomal enzymes, fluorescent material was detected in DNA exposed to high concentrations of the particle extract, but probably not as a result of covalent binding because the mutagenic activity of the particle extract remained unchanged during prolonged incubation with DNA. This stability is in contrast to the rapid decrease in mutagenic activity of benzo[a]pyrene-4,5-oxide during incubation with DNA. Thus, direct mutation of bacteria by the particle extract may require activation by bacterial enzymes as is known to occur with nitroaromatic compounds.     

Concepts of human exposure to air pollution

In recent years, considerable attention has focused on the concept of “human exposure” to environmental pollutants, but different investigators seem to have developed different definitions of this concept and used different approaches for estimating it. This paper reviews a number of “exposure” studies in a single environmental medium—air pollution—to see how others have defined this concept in the literature. Many previous investigators unfortunately calculate “exposures” by relying on data from fixed air monitoring stations, and they assume that people are located in the same place, usually their residential address, throughout a 24-h period. However, a second body of literature shows that fixed air monitoring stations do not necessarily reflect human exposures, because concentrations observed indoors—in homes, offices, factories, and motor vehicles—differ from those observed at fixed stations, and people usually spend considerable time in these locations. In an effort to standardize the nomenclature dealing with exposures, a definition is proposed in which the pollutant must come into contact with the physical boundary of the person. Then, exposure of person i to pollutant concentration c is viewed as two events occurring jointly: person i is present at a particular location, and concentration c is present at the same location. Mathematical definitions for “integrated exposure,” “average exposure,” and “standardized exposure” with various averaging periods also are introduced. Finally, two different yet compatible research approaches are suggested for determining human exposures to air pollution.     

Assessment of air quality in Turin by personal monitoring of nonsmokers for respirable suspended particles and environmental tobacco smoke

Exposure to respirable suspended particles (RSP), environmental tobacco smoke (ETS) particles, nicotine, and 3-ethenylpyridine (3-EP) was assessed in Turin for 188 subjects during February and March 1995. Personal monitors were worn over a 24-h period, each subject providing a saliva sample for cotinine analysis both prior to and following the monitoring period. Comprehensive lifestyle questionnaires were also completed before and after the 24-h monitoring period. The study comprised housewives in one group, primarily for assessing exposures in the home, and office workers in a second group to assess exposures in the workplace. A single personal monitor was worn by each participating housewife, while employed subjects wore one monitor at work and a separate monitor at home and elsewhere. Based on median 24-h time-weighted average exposures, the most highly exposed subjects to RSP, ETS particles, nicotine, and 3-EP were office workers living with smokers and employed in locations where smoking was allowed. Annualised exposures for nonsmokers living and working in smoking environments indicate that the home contribution to RSP is between 3 and 4 times that obtained from the workplace. Similarly nicotine and ETS particle contributions from the home are, respectively, 4 and 7 times more than those obtained from the workplace. Subjects living and working with smokers had the highest median saliva cotinine levels of 1.7 ng mL⁻¹. Using a cut off level of 25 ng mL⁻¹, up to 6.5% of subjects were found to have misreported themselves as nonsmokers.     

Indoor air quality: Radon—Report on a WHO working group

The WHO Regional Office for Europe organized a working group in Dubrovnik, Yugoslavia, on 26–30 August 1985, which discussed radon as a pollutant affecting indoor air quality. Much of the natural background radiation to which the general public is exposed comes from the decay of ²²⁶Ra which produces radon gas and other products. Because radium is a trace element in most rock and soil, indoor concentrations of radon can come from a wide variety of substances, such as building materials and the soil under building foundations. Tap water taken from wells or underground springs may be an additional source. Radon daughter concentrations are considerably higher indoors than outdoors and are of the order of 2–5 Bq m⁻³ equilibrium equivalent radon (EER) concentration. It has been estimated that current exposure to radon gas could account for as much as 5–15% of all lung cancer deaths. It was recommended that, in general, buildings with concentrations of more than 100 Bq m⁻³ EER, as an annual average, should be considered for remedial action to lower such concentrations if simple measures are possible.     

Seasonal variation in outdoor,indoor, and personal air pollution exposures of women using wood stoves in the Tibetan Plateau: Baseline assessment for an energy intervention study

Cooking and heating with coal and biomass is the main source of household air pollution in China and a leading contributor to disease burden. As part of a baseline assessment for a household energy intervention program, we enrolled 205 adult women cooking with biomass fuels in Sichuan, China and measured their 48-h personal exposure to fine particulate matter (PM_2.5) and carbon monoxide (CO) in winter and summer. We also measured the indoor 48-h PM_2.5 concentrations in their homes and conducted outdoor PM_2.5 measurements during 101 (74) days in summer (winter). Indoor concentrations of CO and nitrogen oxides (NO, NO₂) were measured over 48-h in a subset of ~ 80 homes. Women's geometric mean 48-h exposure to PM_2.5 was 80 μg/m³ (95% CI: 74, 87) in summer and twice as high in winter (169 μg/m³ (95% CI: 150, 190), with similar seasonal trends for indoor PM_2.5 concentrations (winter: 252 μg/m³; 95% CI: 215, 295; summer: 101 μg/m³; 95% CI: 91, 112). We found a moderately strong relationship between indoor PM_2.5 and CO (r = 0.60, 95% CI: 0.46, 0.72), and a weak correlation between personal PM_2.5 and CO (r = 0.41, 95% CI: − 0.02, 0.71). NO₂/NO ratios were higher in summer (range: 0.01 to 0.68) than in winter (range: 0 to 0.11), suggesting outdoor formation of NO₂ via reaction of NO with ozone is a more important source of NO₂ than biomass combustion indoors. The predictors of women's personal exposure to PM_2.5 differed by season. In winter, our results show that primary heating with a low-polluting fuel (i.e., electric stove or wood-charcoal) and more frequent kitchen ventilation could reduce personal PM_2.5 exposures. In summer, primary use of a gaseous fuel or electricity for cooking and reducing exposure to outdoor PM_2.5 would likely have the greatest impacts on personal PM_2.5 exposure.     

Elemental analysis of total suspended particulate matter in the ambient air of Baghdad

Samples of atmospheric particulate matter obtained from representative areas of the city of Baghdad were collected on glass fiber filters using a high-volume sampler. Atomic absorption techniques were used to analyze the total suspended particulates (TSP) for the following trace metals; Fe, Cu, Zn, Pb, Mn, Cr, Cd, Co, and Hg. Sulfates were measured by turbidemetric method. Ion-selective electrodes was used for chloride analysis. It is concluded that the major components of TSP in the ambient air of Baghdad consist of mineral dust. Pb and Cd gave high enrichment factor values, which implies enrichment of these two metals from anthropogenic sources. High enrichment factors were also obtained for Zn and Cu. It is also concluded that in this arid area, the black smoke reflectance method is not suitable for measuring total suspended matter gravimetrically.