Indoor and outdoor air quality analysis for the city of Nablus in Palestine: seasonal trends of PM<Subscript>10</Subscript>, PM<Subscript>5.0</Subscript>, PM<Subscript>2.5</Subscript>, and PM<Subscript>1.0</Subscript> of residential homes

Nablus city is an important urban and industrial center in the West Bank, Palestine. The topography of the city, combined with multiple sources of air pollution, creates a potential air quality problem that might affect human health. The indoor and outdoor particle concentration distributions of PM₁₀, PM_5.0, PM_2.5, and PM_1.0 were measured using a Grimm aerosol spectrometer from December 2014 to November 2015, at four roadsides and four urban homes in Nablus. The results of the annual averages of PM₁₀ and PM_2.5 concentrations were found to be at least three times higher than that of the European Air Quality Standards both in indoors and outdoors. The difference in the results between both the roadside and the urban areas was attributed to human and industrial activities in Nablus. The results revealed that the highest concentrations of the particulate matters are during summer, especially June and July, in the roadside areas due to heavy industrial activities during these months. The same behavior was noticed for urban areas during summer and due to other human activities. The results of indoor/outdoor (I/O) ratios were found to be less than, but very close to, 1 for both roadside and urban areas in summer and winter months. In winter times, areas with poor ventilation indicated the existence of additional sources of PM within the indoor environments, especially when smoking cigarettes and using fuel-based heaters such as fireplaces gas and kerosene heaters.     

Indoor air pollutant exposure and determinant factors controlling household air quality for elderly people in Hong Kong

This study investigated the levels and determinant factors of indoor air pollutants including fine particles (PM_2.5), nitrogen dioxide (NO₂), and formaldehyde (HCHO) in 55 households exclusively for the elderly in Hong Kong during summer and winter (Jul.–Sep. 2016 and Nov. 2016–Mar. 2017). The average concentrations of PM_2.5, NO₂, and formaldehyde were 25.3?±?15.0, 40.5?±?16.0, and 26.1?±?22.8 μg/m³ in summer and 34.2?±?19.0, 43.5?±?17.0, and 15.4?±?4.5 μg/m³ in winter, respectively. There were ~?50.3% of households exceeding the World Health Organization indoor air quality standard for PM_2.5 throughout the study, with ~?40.6 and ~61.0% of the households in summer and winter, respectively. The determinant factors for indoor PM_2.5 and NO₂ concentrations were identified as from incense burning and cooking. Cooking with suitable ventilation is an important factor to ease indoor pollutant concentrations. Both of PM_2.5 and NO₂ indoor concentrations showed good correlations with outdoor concentrations. Winter was observed with higher pollutant concentrations than summer except for formaldehyde concentrations. Major factors controlling indoor formaldehyde concentrations are temperature and humidity. The outcome will be useful for the development of future indoor air quality guidelines for Hong Kong.     

Personal exposure to particles in Banská Bystrica, Slovakia

Epidemiological studies have associated adverse health impacts with ambient concentrations of particulate matter (PM), though these studies have been limited in their characterization of personal exposure to PM. An exposure study of healthy nonsmoking adults and children was conducted in Banska Bystrica, Slovakia, to characterize the range of personal exposures to air pollutants and to determine the influence of occupation, season, residence location, and outdoor and indoor concentrations on personal exposures. Twenty-four-hour personal, at-home indoor, and ambient measurements of PM10, PM2.5, sulfate (SO4(2-)) and nicotine were obtained for 18 office workers, 16 industrial workers, and 15 high school students in winter and summer. Results showed that outdoor levels of pollutants were modest, with clear seasonal differences: outdoor PM10 summer/winter mean = 35/45 microg/m3; PM2.5 summer/winter mean = 22/32 microg/m3. SO4(2-) levels were low (4-7 microg/m3) and relatively uniform across the different sample types (personal, indoor, outdoor), areas, and occupational groups. This suggests that SO4(2-) may be a useful marker for combustion mode particles of ambient origin, although the relationship between personal exposures and ambient SO4(2-) levels was more complex than observed in North American settings. During winter especially, the central city area showed higher concentrations than the suburban location for outdoor, personal, and indoor measures of PM10, PM2.5, and to a lesser extent for SO4(2-), suggesting the importance of local sources. For PM2.5 and PM10, ratios consistent with expectations were found among exposure indices for all three subject groups (personal>indoor>outdoor), and between work type (industrial>students>office workers). The ratio of PM2.5 personal to indoor exposures ranged from 1.0 to 3.9 and of personal to outdoor exposures from 1.6 to 4.2. The ratio of PM10 personal to indoor exposures ranged from 1.1 to 2.9 and the ratio of personal to outdoor exposures from 2.1 to 4.1. For a combined group of office workers and students, personal PM10/PM2.5 levels were predicted by statistically significant multivariate models incorporating indoor (for PM2.5) or outdoor (for PM10) PM levels, and nicotine exposure (for PM10). Small but significant fractions of the overall variability, 15% for PM2.5 and 17% for PM10, were explained by these models. The results indicate that central site monitors underpredict actual human exposures to PM2.5 and PM10. Personal exposure to SO4(2-) was found to be predicted by outdoor or indoor SO4(2-) levels with 23-71% of the overall variability explained by these predictors. We conclude that personal exposure measurements and additional demographic and daily activity data are crucial for accurate evaluation of exposure to particles in this setting.     

Influence of Number of Visitors and Weather Conditions on Airborne Particulate Matter Mass Concentrations at The Plitvice Lakes National Park,Croatia During Summer and Autumn

We investigated the influence of local meteorological conditions and number of visitors on ambient particulate matter (PM) mass concentrations and particle fraction ratios at the Plitvice Lakes National Park between July and October 2018. Outdoor mass concentrations of particles with aerodynamic diameters of less than 1, 2.5, and 10 μm (PM₁, PM_2.5, and PM₁₀, respectively) and indoor PM₁ were measured with two light-scattering laser photometers set up near the largest and most visited Kozjak Lake. Our findings suggest that the particles mainly originated from background sources, although some came from local anthropogenic activities. More specifically, increases in both indoor and outdoor mass concentrations coincided with the increase in the number of visitors. Indoor PM₁ concentrations also increased with increase in outdoor air temperature, while outdoor PMs exhibited U-shaped dependence (i.e., concentrations increased only at higher outdoor air temperatures). This behaviour and the decrease in the PM₁/PM_2.5 ratio with higher temperatures suggests that the production and growth of particles is influenced by photochemical reactions. The obtained spectra also pointed to a daily but not to weekly periodicity of PM levels.Key words: anthropogenic PM sources, bivariate polar plot, light-scattering laser photometry, weighted overlapped segment averaging     

Integrated model for the estimation of annual, seasonal, and episode PM10 exposures of children in Rome, Italy

Population exposure assessment plays a central role in developing efficient policies to control the significant health impacts caused by ambient pollution. Policy development requires comparison of alternative control options, which by definition can only be conducted using models. The current work presents results from an integrated model developed for Rome, Italy, to estimate the exposure distributions of children. Spatial distribution of the hourly PM₁₀ levels in 2005 was modeled by a chemical transport model and the modeled concentrations were adjusted using a procedure based on the observed PM₁₀ concentrations at urban stations. The PM₁₀ exposures of children were then estimated accounting for: the time?Cactivity patterns in indoors, outdoors, and in traffic; adjusted ambient levels; and outdoor to indoor infiltration factors. The mean annual exposure level was 22???g/m³, compared to the mean observed ambient concentration at a central station of 48???g/m³, with higher seasonal levels estimated for spring and summer than for autumn and winter. The differences are caused by the longer time spent outdoors and higher residential ventilation rates during spring and summer. The highest integrated exposures took place in the northeasterly districts. Average exposure levels in almost the whole city exceeded 20???g/m³. Short-term exposures were also investigated during a winter PM₁₀ episode for which exposure levels in excess of 30???g/m³ were calculated. Cumulative distribution results for the children indicate that the 24-h limit of 50???g/m3 set for the protection of human health is not exceeded by the exposures of children during the episode. The results of this study are important for a correct interpretation of the epidemiological studies taking into account the relationship of exposures and ambient air quality and for the development of alternative policy options to reduce children??s exposures by lifestyle modification and interventions focused on the reduction of the infiltration of PM₁₀ into indoor environments.     

Effects of airborne particulate matter on respiratory morbidity in asthmatic children

Background

The effects of airborne particulate matter (PM) are a major human health concern. In this panel study, we evaluated the acute effects of exposure to PM on peak expiratory flow (PEF) and wheezing in children.

Methods

Daily PEF and wheezing were examined in 19 asthmatic children who were hospitalized in a suburban city in Japan for approximately 5 months. The concentrations of PM less than 2.5 µm in diameter (PM_2.5) were monitored at a monitoring station proximal to the hospital. Moreover, PM_2.5 concentrations inside and outside the hospital were measured using the dust monitor with a laser diode (PM_2.5(LD)). The changes in PEF and wheezing associated with PM concentration were analyzed.

Results

The changes in PEF in the morning and evening were significantly associated with increases in the average concentration of indoor PM_2.5(LD) 24 h prior to measurement (-2.86 L/min [95%CI: -4.12, -1.61] and -3.59 L/min [95%CI: -4.99, -2.20] respectively, for 10-µg/m³ increases). The change in PEF was also significantly associated with outdoor PM_2.5(LD) concentrations, but the changes were smaller than those observed for indoor PM_2.5(LD). Changes in PEF and concentration of stationary-site PM_2.5 were not associated. The prevalence of wheezing in the morning and evening were also significantly associated with indoor PM_2.5(LD) concentrations (odds ratios = 1.014 [95%CI: 1.006, 1.023] and 1.025 [95%CI: 1.013, 1.038] respectively, for 10-µg/m³ increases). Wheezing in the evening was significantly associated with outdoor PM_2.5(LD) concentration. The effects of indoor and outdoor PM_2.5(LD) remained significant even after adjusting for ambient nitrogen dioxide concentrations.

Conclusion

Indoor and outdoor PM_2.5(LD) concentrations were associated with PEF and wheezing among asthmatic children. Indoor PM_2.5(LD) had a more marked effect than outdoor PM_2.5(LD) or stationary-site PM_2.5.Key words: Particulate Matter, Asthma, Peak Expiratory Flow Rate, Respiratory Sounds     

Particulate matter measurements PM2.5 and PM10 in Rome: comparison indoor/outdoor

The concentration of airborne particulate matter (PM2.5 and PM10) was assessed over 12 months (1999-2000) both outdoor and indoor (workplaces and homes without major PM sources) through a manual gravimetric method. Mean concentration values outdoors were moderately lower than indoor concentrations in summer, but higher in winter. The correlations between outdoor and indoor values are statistically significant, especially for PM2.5 in winter. The position of indoor sites with respect to street level was immaterial as far as mean values is concerned, whilst maximum values presented some differences accordingly. Day-to-day variability was higher outside than inside, especially in winter. The PM2.5/PM10 ratio was higher indoors, probably owing to the higher sedimentation speed of the coarse fraction.     

Characterization of coarse particulate matter in school gyms

We investigated the mass concentration, mineral composition and morphology of particles resuspended by children during scheduled physical education in urban, suburban and rural elementary school gyms in Prague (Czech Republic). Cascade impactors were deployed to sample the particulate matter. Two fractions of coarse particulate matter (PM_10−2.5 and PM_2.5−1.0) were characterized by gravimetry, energy dispersive X-ray spectrometry and scanning electron microscopy. Two indicators of human activity, the number of exercising children and the number of physical education hours, were also recorded. Lower mass concentrations of coarse particulate matter were recorded outdoors (average PM_10−2.5 4.1–7.4 μg m⁻³ and PM_2.5−1.0 2.0–3.3 μg m⁻³) than indoors (average PM_10−2.5 13.6–26.7 μg m⁻³ and PM_2.5−1.0 3.7–7.4 μg m⁻³). The indoor concentrations of coarse aerosol were elevated during days with scheduled physical education with an average indoor–outdoor (I/O) ratio of 2.5–16.3 for the PM_10−2.5 and 1.4–4.8 for the PM_2.5−1.0 values. Under extreme conditions, the I/O ratios reached 180 (PM_10−2.5) and 19.1 (PM_2.5−1.0). The multiple regression analysis based on the number of students and outdoor coarse PM as independent variables showed that the main predictor of the indoor coarse PM concentrations is the number of students in the gym. The effect of outdoor coarse PM was weak and inconsistent. The regression models for the three schools explained 60–70% of the particular dataset variability. X-ray spectrometry revealed 6 main groups of minerals contributing to resuspended indoor dust. The most abundant particles were those of crustal origin composed of Si, Al, O and Ca. Scanning electron microscopy showed that, in addition to numerous inorganic particles, various types of fibers and particularly skin scales make up the main part of the resuspended dust in the gyms. In conclusion, school gyms were found to be indoor microenvironments with high concentrations of coarse particulate matter, which can contribute to increased short-term inhalation exposure of exercising children.     

Indoor–outdoor concentrations of particulate matter in nine microenvironments of a mix-use commercial building in megacity Delhi

Three naturally and six mechanically ventilated microenvironments (MEs) of a mix-use commercial building in Delhi are used to study indoor–outdoor (I/O) relationships of particulate matter ≤10 μm (PM₁₀), ≤2.5 μm (PM_2.5), and ≤1 μm (PM₁). Effect of environmental and occupancy parameters on the concentrations of PM during working and non-working hours (i.e., activity and non-activity periods, respectively) are also investigated. Average outdoor concentration of PM₁₀ and PM_2.5 were found to exceed the 24-h averaged national standard values, showing a polluted environment surrounding the studied building. During working hours, indoor PM₁₀ concentration was found 6–10 times, both PM_2.5 and PM₁ were 1.5–2 times, higher than the non-working hours in the selected MEs. The variations of indoor concentrations were highest (17.1–601.2 μg/m³) for PM₁₀ compared with PM_2.5 (16.9–102.6 μg/m³) and PM_1.0 (10.6–63.6 μg/m³). The I/O for PM₁₀, PM_2.5, and PM_1.0 varied from 0.37–3.1, 0.2–3.2, and 0.17–2.9, respectively. The results suggest highest I/O for PM₁₀, PM_2.5, and PM₁ as 3.1, 2.15, and 1.76, respectively, in all the three natural-ventilated MEs (canteen, kitchen, reception). Irrespective of PM types, the average I/O was <1 for mechanically ventilated MEs compared with >1 for naturally ventilated MEs. As opposed to PM₁, better correlation (r?>?0.6) was noted between indoor PM₁₀, PM_2.5, and CO₂ concentrations in most of the airtight MEs.     

Temporal changes of particulate concentration in the ambient air over the city of Zahedan, Iran

Air pollution in developing countries has recently become a serious environmental problem, which needs more active air quality monitoring and analyses. To assess air quality characteristics over the city of Zahedan, southeast Iran, airborne particulate matter (PM) concentrations with aerodynamic diameters of <10, <2.5, and <1.0 μm were measured during the period July 2008 to March 2010 using an Environmental Dust Monitor (EDM-180). The data were analyzed on a daily, monthly, and seasonal basis. The highest monthly mean PM₁₀ levels (172 μg m^?3) were recorded during the summer period (June–August), presumably due to frequent dust storms from the nearby Sistan desert located to the north, while less PM₁₀ concentrations are recorded in winter (December–February; 101 μg m^?3). Linear regression analysis between the PM_2.5 and PM₁₀ time series reveals high correlation coefficients (r?>?0.82) for all seasons, implying that PM₁₀ and PM_2.5 may have the same source regions or that they are influenced by the same local conditions. In contrast, neutral correlation is found between PM₁₀ and PM_1.0 in autumn and winter. Taking into account that the annual variation of PM_1.0 exhibits a clear pattern of peaking in winter and dropping in summer (in contrast to PM₁₀), it is suspected that PM_1.0 is of different origin than PM₁₀ and mainly influenced by local anthropogenic emissions. The daily PM₁₀ variation is strongly seasonally defined. The maximum PM₁₀ concentrations occur in the morning hours during winter, autumn (September–November), and early spring (March), while in summer, PM₁₀ concentrations increase significantly in the afternoon, closely associated with the intense northerly winds blowing from the desert. As far as the Air Quality Index (AQI) is concerned, its highest monthly values occur in summer, while they are reduced in winter. Desert dust aerosols are found to be the major component in determining the AQI in Zahedan. The analysis shows that 15.3% of the days are unhealthy for sensitive people, while 2% are considered as hazardous.     

The effect of outdoor air and indoor human activity on mass concentrations of PM(10), PM(2.5), and PM(1) in a classroom

The 12-h mass concentration of PM₁₀, PM_2.5, and PM₁ was measured in a lecturing room by means of three co-located Harvard impactors. The filters were changed at 8 AM and at 8 PM to cover the periods of presence and absence of students. Concentrations were assessed by gravimetry. Ambient PM₁₀ data were available for corresponding 12-h intervals from the nearest state air-quality-monitoring network station. The data were pooled into four periods according to the presence and absence of students—Monday-Thursday day (workday daytime), Monday-Thursday night (workday night), Friday-Sunday day (weekend daytime), and Friday-Sunday night (weekend night). Average indoor workday daytime concentrations were 42.3, 21.9 and 13.7 μg m⁻³, workday night were 20.9, 19.1 and 15.2 μg m⁻³, weekend daytime were 21.9, 18.1 and 11.4 μg m⁻³, and weekend night were 24.5, 21.3, and 15.6 μg m⁻³ for PM₁₀, PM_2.5, and PM₁, respectively. The highest 12-h mean, median, and maximum (42.3, 43.0, and 76.2 μg m⁻³, respectively) indoor concentrations were recorded on workdays during the daytime for PM₁₀. The statistically significant (r=0.68,P<0.0009) correlation between the number of students per hour per day and the indoor coarse fraction calculated as PM_10−2.5 during daytime on workdays indicates that the presence of people is an important source of coarse particles indoor. On workdays, the daytime PM₁₀ indoor/outdoor ratio was positively associated (r=0.93) with an increasing indoor coarse fraction (PM_10-2.5), also indicating that an important portion of indoor PM₁₀ had its source inside the classroom. With the exception of the calculated coarse fraction (PM_10-2.5), all of the measured indoor particulate matter fractions were significantly highly correlated with outdoor PM₁₀ and negatively correlated with wind velocity, showing that outdoor levels of particles influence their indoor concentrations.     

Exposure assessment of particulate matter for susceptible populations in Seattle

In this article we present results from a 2-year comprehensive exposure assessment study that examined the particulate matter (PM) exposures and health effects in 108 individuals with and without chronic obstructive pulmonary disease (COPD), coronary heart disease (CHD), and asthma. The average personal exposures to PM with aerodynamic diameters < 2.5 microm (PM2.5) were similar to the average outdoor PM2.5 concentrations but significantly higher than the average indoor concentrations. Personal PM2.5 exposures in our study groups were lower than those reported in other panel studies of susceptible populations. Indoor and outdoor PM2.5, PM10 (PM with aerodynamic diameters < 10 microm), and the ratio of PM2.5 to PM10 were significantly higher during the heating season. The increase in outdoor PM10 in winter was primarily due to an increase in the PM2.5 fraction. A similar seasonal variation was found for personal PM2.5. The high-risk subjects in our study engaged in an equal amount of dust-generating activities compared with the healthy elderly subjects. The children in the study experienced the highest indoor PM2.5 and PM10 concentrations. Personal PM2.5 exposures varied by study group, with elderly healthy and CHD subjects having the lowest exposures and asthmatic children having the highest exposures. Within study groups, the PM2.5 exposure varied depending on residence because of different particle infiltration efficiencies. Although we found a wide range of longitudinal correlations between central-site and personal PM2.5 measurements, the longitudinal r is closely related to the particle infiltration efficiency. PM2.5 exposures among the COPD and CHD subjects can be predicted with relatively good power with a microenvironmental model composed of three microenvironments. The prediction power is the lowest for the asthmatic children.     

Mass size distribution and chemical composition of the surface layer of summer and winter airborne particles in Zabrze, Poland

Mass size distributions of ambient aerosol were measured in Zabrze, a heavily industrialized city of Poland, during a summer and a winter season. The chemical analyses of the surface layer of PM₁₀, PM_2.5 and PM₁ in this area were also performed by X-ray photoelectron spectroscopy (XPS). Results suggested that the influence of an atmospheric aerosol on the health condition of Zabrze residents can be distinctly stronger in winter than in summer because of both: higher concentration level of particulate matter (PM) and higher contribution of fine particles in winter season compared to summer. In Zabrze in June (summer) PM₁₀ and PM_2.5 reached about 20 and 14 μg/m³, respectively, while in December (winter) 57 and 51 μg/m³, respectively. The XPS analysis showed that elemental carbon is the major surface component of studied airborne particles representing about 78%–80% (atomic mass) of all detected elements.     

Quantifying daily contributions of source regions to PM concentrations in Marseille based on the trails of incoming air masses

The hourly trails (trajectory points) of incoming air masses have been used in this study in order to compose independent variables for the quantification of regional PM₁₀ and PM_2.5 contributions in Marseille (Southern France), and also for the estimation of the atmospheric dispersion effect. These prediction variables were used as input for a Multiple Linear Regression Model (MLRM) in order to estimate daily PM₁₀ and PM_2.5 concentrations in Marseille. For a more exact localization of fine and coarse particle sources, during cold and warm period, our analysis was supplemented by the findings of Concentration Weighted Trajectory (CWT) algorithm on a 0.5°·0.5° resolution grid. A strong coherence was revealed among measured and estimated daily levels of PM₁₀ and PM_2.5; thus, the proposed MLRM can be a useful tool for assessing air quality in terms of atmospheric circulation. Increased PM contributions in Marseille from local and all-around emission sources were indicated by MLRM primarily within cold seasons. In addition, Northeast (NE) atmospheric circulation was associated by MLRM and CWT with extreme intrusions of exogenous particulate air pollution from Central Europe, during winter and early spring. Throughout warm period, the scarceness of NE airflows prevented the transportation of aerosols from continental Europe. Episodes of desert dust transportation from Northwest Africa (Algeria and Tunisia) had a clear footprint in the PM_COARSE (=PM₁₀-PM_2.5) fraction.     

Infiltration of forest fire and residential wood smoke: an evaluation of air cleaner effectiveness

Communities impacted by fine-particle air pollution (particles with an aerodynamic diameter less than 2.5 microm; PM(2.5)) from forest fires and residential wood burning require effective, evidence-based exposure-reduction strategies. Public health recommendations during smoke episodes typically include advising community members to remain indoors and the use of air cleaners, yet little information is available on the effectiveness of these measures. Our study attempted to address the following objectives: to measure indoor infiltration factor (F(inf)) of PM(2.5) from forest fires/wood smoke, to determine the effectiveness of high-efficiency particulate air (HEPA) filter air cleaners in reducing indoor PM(2.5), and to analyze the home determinants of F(inf) and air cleaner effectiveness (ACE). We collected indoor/outdoor 1-min PM(2.5) averages and 48-h outdoor PM(2.5) filter samples for 21 winter and 17 summer homes impacted by wood burning and forest fire smoke, respectively, during 2004-2005. A portable HEPA filter air cleaner was operated indoors with the filter removed for one of two sampling days. Particle F(inf) and ACE were calculated for each home using a recursive model. We found mean F(inf)+/-SD was 0.27+/-0.18 and 0.61+/-0.27 in winter (n=19) and summer (n=13), respectively, for days when HEPA filters were not used. Lower F(inf)+/-SD values of 0.10+/-0.08 and 0.19+/-0.20 were found on corresponding days when HEPA filters were in place. Mean+/-SD ACE ([F(inf) without filter-F(inf) with filter]/F(inf) without filter) in winter and summer were 55+/-38% and 65+/-35%, respectively. Number of windows and season predicted F(inf) (P<0.001). No significant predictors of ACE were identified. Our findings show that remaining indoors combined with use of air cleaner can effectively reduce PM(2.5) exposure during forest fires and residential wood burning.     

Carbonaceous aerosols at an industrial site in Southeastern Spain

The aim of the present study is to evaluate the possible influence of cement works on carbonaceous aerosol concentrations in the western Mediterranean. A PM_2.5 and PM₁₀ sampling campaign was performed between September 2005 and August 2006 in a suburban area close to two cement plants in southeastern Spain. All the samples were analyzed for elemental carbon (EC) and organic carbon (OC) using a thermal-optical method. The percentage contribution of total carbon to annual PM mass concentrations was 20 % for PM_2.5 and 10 % for PM₁₀. These values were lower than those reported for other European urban and industrial locations because of a higher proportion of crustal matter and secondary inorganic aerosols in the study area. The seasonal cycle of OC concentrations, with higher values in winter than in summer, was influenced by the transport of cement plants’ emissions to the sampling site, as corroborated by the results obtained from the CPF analysis. In contrast, no clear effect of cement plants’ emissions on EC concentrations could be established. The concentrations of secondary organic carbon (SOC) in the PM_2.5 fraction were estimated using the EC tracer method. The contribution of SOC to the annual OC concentration was 50 %, varying between 30 % in July and 70 % in February. Contrary to expectations, SOC levels also exhibited a summer minimum, suggesting that photochemistry cannot be considered to be the leading factor in the formation of secondary organic aerosols in the research area.     

Indoor, outdoor, and regional summer and winter concentrations of PM10, PM2.5, SO4(2)-, H+, NH4+, NO3-, NH3, and nitrous acid in homes with and without kerosene space heaters

Twenty-four-hour samples of PM10 (mass of particles with aerodynamic diameter < or = 10 microm), PM2.5, (mass of particles with aerodynamic diameter < or = 2.5 microm), particle strong acidity (H+), sulfate (SO42-), nitrate (NO3-), ammonia (NH3), nitrous acid (HONO), and sulfur dioxide were collected inside and outside of 281 homes during winter and summer periods. Measurements were also conducted during summer periods at a regional site. A total of 58 homes of nonsmokers were sampled during the summer periods and 223 homes were sampled during the winter periods. Seventy-four of the homes sampled during the winter reported the use of a kerosene heater. All homes sampled in the summer were located in southwest Virginia. All but 20 homes sampled in the winter were also located in southwest Virginia; the remainder of the homes were located in Connecticut. For homes without tobacco combustion, the regional air monitoring site (Vinton, VA) appeared to provide a reasonable estimate of concentrations of PM2.5 and SO42- during summer months outside and inside homes within the region, even when a substantial number of the homes used air conditioning. Average indoor/outdoor ratios for PM2.5 and SO42- during the summer period were 1.03 +/- 0.71 and 0.74 +/- 0.53, respectively. The indoor/outdoor mean ratio for sulfate suggests that on average approximately 75% of the fine aerosol indoors during the summer is associated with outdoor sources. Kerosene heater use during the winter months, in the absence of tobacco combustion, results in substantial increases in indoor concentrations of PM2.5, SO42-, and possibly H+, as compared to homes without kerosene heaters. During their use, we estimated that kerosene heaters added, on average, approximately 40 microg/m3 of PM2.5 and 15 microg/m3 of SO42- to background residential levels of 18 and 2 microg/m3, respectively. Results from using sulfuric acid-doped Teflon (E.I. Du Pont de Nemours & Co., Wilmington, DE) filters in homes with kerosene heaters suggest that acid particle concentrations may be substantially higher than those measured because of acid neutralization by ammonia. During the summer and winter periods indoor concentrations of ammonia are an order of magnitude higher indoors than outdoors and appear to result in lower indoor acid particle concentrations. Nitrous acid levels are higher indoors than outdoors during both winter and summer and are substantially higher in homes with unvented combustion sources.     

Exposure of children studying in schools of India to PM levels and metal contamination: sources and their identification

The concentration of particulate matter (PM)₁₀, PM_5.0, PM_2.5, PM_1.0, PM_0.50, and PM_0.25 was measured along with heavy metals (Fe, Zn, Cu, Cd, Cr, Mn, Ni, and Pb) collected from settling dust in the indoor–outdoor environment of roadside and residentially located schools of Agra City, from January 2008 to May 2009. PM indoor/outdoor ratios at the roadside and residentially located schools were also determined by the meteorological parameters like temperature, humidity, and wind speed and air exchange rate. Metal geoaccumulation index shows that the contamination of Fe, Cd, Cr, Ni, Pb, and Mn was in abundant quantity in residential and roadside soil dust of the schools. The enrichment factor was calculated using Ca as a reference to the trace metal species to identify the sources. Three factors in inside and three outside the classrooms of roadside and residentially located schools were identified. These factors reflected source soil dust, road dust, vehicle emissions, industrial emissions, metal processes, and incineration activities and their contributions were estimated using principal component analysis. Measurements of such exposure levels would be helpful in prevention of environmental risks to schoolchildren at a global level for better and healthy mind of children studying at schools.     

Secondhand Tobacco Smoke Exposure in Open and Semi-Open Settings: A Systematic Review

Background: Some countries have recently extended smoke-free policies to particular outdoor settings; however, there is controversy regarding whether this is scientifically and ethically justifiable.Objectives: The objective of the present study was to review research on secondhand smoke (SHS) exposure in outdoor settings.Data sources: We conducted different searches in PubMed for the period prior to September 2012. We checked the references of the identified papers, and conducted a similar search in Google Scholar.Study selection: Our search terms included combinations of “secondhand smoke,” “environmental tobacco smoke,” “passive smoking” OR “tobacco smoke pollution” AND “outdoors” AND “PM” (particulate matter), “PM_2.5” (PM with diameter ≤ 2.5 µm), “respirable suspended particles,” “particulate matter,” “nicotine,” “CO” (carbon monoxide), “cotinine,” “marker,” “biomarker” OR “airborne marker.” In total, 18 articles and reports met the inclusion criteria.Results: Almost all studies used PM_2.5 concentration as an SHS marker. Mean PM_2.5 concentrations reported for outdoor smoking areas when smokers were present ranged from 8.32 to 124 µg/m³ at hospitality venues, and 4.60 to 17.80 µg/m³ at other locations. Mean PM_2.5 concentrations in smoke-free indoor settings near outdoor smoking areas ranged from 4 to 120.51 µg/m³. SHS levels increased when smokers were present, and outdoor and indoor SHS levels were related. Most studies reported a positive association between SHS measures and smoker density, enclosure of outdoor locations, wind conditions, and proximity to smokers.Conclusions: The available evidence indicates high SHS levels at some outdoor smoking areas and at adjacent smoke-free indoor areas. Further research and standardization of methodology is needed to determine whether smoke-free legislation should be extended to outdoor settings.