Inorganic and Carbonaceous Components in Indoor/Outdoor Particulate Matter in Two Residential Houses in Oslo,Norway

Abstract

A detailed analysis of indoor/outdoor physicochemical aerosol properties has been performed. Aerosol measurements were taken at two dwellings, one in the city center and the other in the suburbs of the Oslo metropolitan area, during summer/fall and winter/spring periods of 2002–2003. In this paper, emphasis is placed on the chemical characteristics (water-soluble ions and carbonaceous components) of fine (PM_2.5) and coarse (PM_2.5–10) particles and their indoor/outdoor relationship. Results demonstrate that the carbonaceous species were dominant in all fractions of the PM₁₀ particles (cut off size: 0.09–11.31 μm) during all measurement periods, except winter 2003, when increased concentrations of water-soluble inorganic ions were predominant because of sea salt transport. The concentration of organic carbon was higher in the fine and coarse PM₁₀ fractions indoors, whereas elemental carbon was higher indoors only in the coarse fraction. In regards to the carbonaceous species, local traffic and secondary organic aerosol formation were, probably, the main sources outdoors, whereas indoors combustion activities such as preparation of food, burning of candles, and cigarette smoking were the main sources. In contrast, the concentrations of water-soluble inorganic ions were higher outdoors than indoors. The variability of water-soluble inorganic ion concentrations outdoors was related to changes in emissions from local anthropogenic sources, long-range transport of particles, sea salt emissions, and resuspension of roadside and soil dusts. In the indoor environment the infiltration of the outdoor air indoors was the major source of inorganic ions.     

Effect of Gas and Kerosene Space Heaters on Indoor Air Quality: A Study in Homes of Santiago,Chile

Abstract

The impact of outdoor and indoor pollution sources on indoor air quality in Santiago, Chile was investigated. Toward this end, 16 homes were sampled in four sessions. Each session included an outdoor site and four homes using different unvented space heaters (electric or central heating, compressed natural gas, liquefied petroleum gas, and kerosene). Average outdoor fine particulate matter (PM_2.5) concentrations were very high (55.9 μg·m^-3), and a large fraction of these particles penetrated indoors. PM_2.5 and several PM_2.5 components (including sulfate, elemental carbon, organic carbon, metals, and polycyclic aromatic hydrocarbons) were elevated in homes using kerosene heaters. Nitrogen dioxide (NO₂) and ultrafine particles (UFPs) were higher in homes with combustion heaters as compared with those with electric heaters or central heating. A regression model was used to assess the effect of heater use on continuous indoor PM_2.5 concentrations when windows were closed. The model found an impact only for kerosene heaters (45.8 μg m^-3).     

The Influences of Ambient Particle Composition and Size on Particle Infiltration in Los Angeles,CA, Residences

Abstract

Particle infiltration is a key determinant of the indoor concentrations of ambient particles. Few studies have examined the influence of particle composition on infiltration, particularly in areas with high concentrations of volatile particles, such as ammonium nitrate (NH₄NO₃). A comprehensive indoor monitoring study was conducted in 17 Los Angeles–area homes. As part of this study, indoor/outdoor concentration ratios during overnight (nonindoor source) periods were used to estimate the fraction of ambient particles remaining airborne indoors, or the particle infiltration factor (F_INF), for fine particles (PM_2.5), its nonvolatile (i.e., black carbon [BC]) and volatile (i.e., nitrate [NO₃ ^?]) components, and particle sizes ranging between 0.02 and 10 μm. F_INF was highest for BC (median = 0.84) and lowest for NO₃ ^? (median = 0.18). The low F_INF for NO₃ ^? was likely because of volatilization of NO₃ ^? particles once indoors, in addition to depositional losses upon building entry. The F_INF for PM_2.5 (median = 0.48) fell between those for BC and NO₃ ^?, reflecting the contributions of both particle components to PM_2.5. F_INF varied with particle size, air-exchange rate, and outdoor NO₃ ^? concentrations. The F_INF for particles between 0.7 and 2 μm in size was considerably lower during periods of high as compared with low outdoor NO₃ ^? concentrations, suggesting that outdoor NO₃ ^? particles were of this size. This study demonstrates that infiltration of PM_2.5 varies by particle component and is lowest for volatile species, such as NH₄NO₃. Our results suggest that volatile particle components may influence the ability for outdoor PM concentrations to represent indoor and, thus, personal exposures to particles of ambient origin, because volatilization of these particles causes the composition of PM_2.5 to differ indoors and outdoors. Consequently, particle composition likely influences observed epidemiologic relationships based on outdoor PM concentrations, especially in areas with high concentrations of NH₄NO₃ and other volatile particles.     

Potential effects of particulate matter from combustion during services on human health and on works of art in medieval churches in Cyprus

Indoor and outdoor particulate matter (PM_0.3-10) number concentrations were established in two medieval churches in Cyprus. In both churches incense was burnt occasionally during Mass. The highest indoor PM_0.5-1 concentrations compared with outdoors (10.7 times higher) were observed in the church that burning of candles indoors was allowed. Peak indoor black carbon concentration was 6.8 μg m⁻³ in the instances that incense was burning and 13.4 μg m⁻³ in the instances that the candles were burning (outdoor levels ranged between 0.6 and 1.3 μg m⁻³). From the water soluble inorganic components determined in PM₁₀, calcium prevailed in all samples indoors or outdoors, whilst high potassium concentration indoors were a clear marker of combustion. Indoor sources of PM were clearly identified and their emission strengths were estimated via modeling of the results. Indoor estimated PM_0.3-10 mass concentrations exceeded air quality standards for human health protection and for the preservation of works of art.     

Outdoor and indoor factors influencing particulate matter and carbon dioxide levels in naturally ventilated urban homes

ABSTRACT

The present study investigated indoor and outdoor concentrations of two particulate matter size fractions (PM₁₀ and PM_2.5) and CO₂ in 20 urban homes ventilated naturally and located in one congested residential and commercial area in the city of Alexandria, Egypt. The results indicate that the daily mean PM_2.5 concentrations measured in the ambient air, living rooms, and kitchens of all sampling sites exceeded the WHO guideline by 100%, 65%, and 95%, respectively. The daily mean outdoor and indoor PM₁₀ levels in all sampling sites were found to exceed the WHO guideline by 100% and 80%, respectively. The indoor PM₁₀ and PM_2.5 concentrations were significantly correlated with their corresponding outdoor levels, as natural ventilation through opening doors and windows allowed direct transfer of outdoor airborne particles into the indoor air. Most of the kitchens investigated had higher indoor concentrations of PM_2.5 and CO₂ than in living rooms. The elevated levels of PM_2.5 and CO₂ in domestic kitchens were probably related to inadequate ventilation. The current study attempted to understand the sources and the various indoor and outdoor factors that affect indoor PM₁₀, PM_2.5 and CO₂ concentrations. Several domestic activities, such as smoking, cooking, and cleaning, were found to constitute important sources of indoor air pollution. The indoor pollution caused by PM_2.5 was also found to be more serious in the domestic kitchens than in the living rooms and the results suggest that exposure to PM_2.5 is high and highlights the need for more effective control measures.

Implications: Indoor air pollution is a complex problem that involves many determinant factors. Understanding the relationships and the influence of various indoor and outdoor factors on indoor air quality is very important to prioritize control measures and mitigation action plans. There is currently a lack of research studies in Egypt to investigate determinant factors controlling indoor air quality for urban homes. The present study characterizes the indoor and outdoor concentrations of PM₁₀, PM_2.5, and CO₂ in residential buildings in Alexandria city. The study also determines the indoor and outdoor factors which influence the indoor PM and CO₂ concentrations as well as it evaluates the potential indoor sources in the selected homes. This research will help in the development of future indoor air quality standards for Egypt.     

A functional group characterization of organic PM2.5 exposure: Results from the RIOPA study

The functional group (FG) composition of urban residential outdoor, indoor, and personal fine particle (PM_2.5) samples is presented and used to provide insights relevant to organic PM_2.5 exposure. PM_2.5 samples (48 h) were collected during the Relationship of Indoor, Outdoor, and Personal Air (RIOPA) study at 219 non-smoking homes (once or twice) in Los Angeles County, CA, Elizabeth, NJ, and Houston, TX. Fourier transform infrared (FTIR) spectra of PM_2.5 samples were collected, and FG absorbances were quantified by partial least squares (PLS) regression, a multivariate calibration method.There is growing evidence in the literature that a large majority of indoor-generated PM_2.5 is organic. The current research suggests that indoor-generated PM_2.5 is enriched in aliphatic carbon–hydrogen (CH) FGs relative to ambient outdoor PM_2.5. Indoor-generated CH exceeded outdoor-generated CH in 144 of the 167 homes for which indoor or outdoor CH was measurable; estimated indoor emission rates are provided. The strong presence of aliphatic CH FGs in indoor PM_2.5 makes particulate organic matter substantially less polar indoors and in personal exposures than outdoors. This is a substantial new finding. Based on the quantified FGs, the average organic molecular weight (OM) per carbon weight (OC), a measure of the degree of oxygenation of organic PM, is in the range of 1.7–2.6 for outdoor samples and 1.3–1.7 for indoor and personal samples. Polarity or degree of oxygenation effects particle deposition in exposure environments and in the respiratory system.     

PM2.5, soot and NO2 indoor–outdoor relationships at homes,pre-schools and schools in Stockholm,Sweden

In developed nations people spend about 90% of their time indoors. The relationship between indoor and outdoor air pollution levels is important for the understanding of the health effects of outdoor air pollution. Although other studies describe both the outdoor and indoor atmospheric environment, few excluded a priori major indoor sources, measured the air exchange rate, included more than one micro-environment and included the presence of human activity. PM_2.5, soot, NO₂ and the air exchange rate were measured during winter and summer indoors and outdoors at 18 homes (mostly apartments) of 18 children (6–11-years-old) and also at the six schools and 10 pre-schools that the children attended. The three types of indoor environments were free of environmental tobacco smoke and gas appliances, as the aim was to asses to what extent PM_2.5, soot and NO₂ infiltrate from outdoors to indoors. The median indoor and outdoor PM_2.5 levels were 8.4 μg m^?3 and 9.3 μg m^?3, respectively. The median indoor levels for soot and NO₂ were 0.66 m^?1 × 10^?5 and 10.0 μg m^?3, respectively. The respective outdoor levels were 0.96 m^?1 × 10^?5 and 12.4 μg m^?3. The median indoor/outdoor (I/O) ratios were 0.93, 0.76 and 0.92 for PM_2.5, soot and NO₂, respectively. Their infiltration factors were influenced by the micro-environment, ventilation type and air exchange rate, with aggregated values of 0.25, 0.55 and 0.64, respectively. Indoor and outdoor NO₂ levels were strongly associated (R² = 0.71), followed by soot (R² = 0.50) and PM_2.5 (R² = 0.16). In Stockholm, the three major indoor environments occupied by children offer little protection against combustion-related particles and gases in the outdoor air. Outdoor PM_2.5 seems to infiltrate less, but indoor sources compensate.     

Investigation of time-resolved atmospheric conditions and indoor/outdoor particulate matter concentrations in homes with gas and biomass cook stoves in Nogales,Sonora, Mexico

This paper reports findings from a case study designed to investigate indoor and outdoor air quality in homes near the United States–Mexico border. During the field study, size-resolved continuous particulate matter (PM) concentrations were measured in six homes, while outdoor PM was simultaneously monitored at the same location in Nogales, Sonora, Mexico, during March 14–30, 2009. The purpose of the experiment was to compare PM in homes using different fuels for cooking, gas versus biomass, and to obtain a spatial distribution of outdoor PM in a region where local sources vary significantly (e.g., highway, border crossing, unpaved roads, industry). Continuous PM data were collected every 6 seconds using a valve switching system to sample indoor and outdoor air at each home location. This paper presents the indoor PM data from each home, including the relationship between indoor and outdoor PM. The meteorological conditions associated with elevated ambient PM events in the region are also discussed. Results indicate that indoor air pollution has a strong dependence on cooking fuel, with gas stoves having hourly averaged median PM₃ concentrations in the range of 134 to 157 μg m^?3 and biomass stoves 163 to 504 μg m^?3. Outdoor PM also indicates a large spatial heterogeneity due to the presence of microscale sources and meteorological influences (median PM₃: 130 to 770 μg m^?3). The former is evident in the median and range of daytime PM values (median PM₃: 250 μg m^?3, maximum: 9411 μg m^?3), while the meteorological influences appear to be dominant during nighttime periods (median PM₃: 251 μg m^?3, maximum: 10,846 μg m^?3). The atmospheric stability is quantified for three nighttime temperature inversion episodes, which were associated with an order of magnitude increase in PM10 at the regulatory monitor in Nogales, AZ (maximum increase: 12 to 474 μg m^?3).

Implications:Regulatory air quality standards are based on outdoor ambient air measurements. However, a large fraction of time is typically spent indoors where a variety of activities including cooking, heating, tobacco smoking, and cleaning can lead to elevated PM concentrations. This study investigates the influence of meteorology, outdoor PM, and indoor activities on indoor air pollution (IAP) levels in the United States–Mexico border region. Results indicate that cooking fuel type and meteorology greatly influence the IAP in homes, with biomass fuel use causing the largest increase in PM concentration.     

Loading Effect Correction for Real-Time Aethalometer Measurements of Fresh Diesel Soot

Abstract

In this study, a correction was developed for the aethalometer to measure real-time black carbon (BC) concentrations in an environment dominated by fresh diesel soot. The relationship between the actual mass-specific absorption coefficient for BC and the BC-dependent attenuation coefficients was determined from experiments conducted in a diesel exposure chamber that provided constant concentrations of fine particulate matter (PM; PM_2.5; PM <2.5 µm in aerodynamic diameter) from diesel exhaust. The aethalometer reported BC concentrations decreasing with time from 48.1 to 31.5 µg m^?3when exposed to constant PM_2.5concentrations of 55 ± 1 µg m^?3and b_scat= 95 ± 3 Mm^?1from diesel exhaust. This apparent decrease in reported light-absorbing PM concentration was used to derive a correction K(ATN) for loading of strong light-absorbing particles onto or into the aethalometer filter tape, which was a function of attenuation of light at 880 nm by the embedded particles.     

Associations between particle physicochemical characteristics and oxidative capacity: An indoor PM10 study in Beijing,China

A study was undertaken to determine the use of a plasmid DNA scission assay to evaluate the causal relationships between particle oxidative capacity and physico-chemistry. Field emission scanning electron microscopy (FESEM), image analysis (IA) and inductively coupled plasma-mass spectrometry (ICP-MS) were employed to investigate the physico-chemical characteristics of indoor PM₁₀ (particulate matter with an aerodynamic diameter of 10 μm or less) in Beijing, China. Six PM₁₀ samples (indoor smoker's living room; indoor non-smoker's living room and kitchen; and outdoor Beijing city; winter versus summer) were selected to represent typical indoor Beijing PM₁₀ environments that contain high particle mass. The PM₁₀ collected from a kitchen and two smoker's homes had the lowest TD₅₀ (toxic dosage of PM₁₀ causing 50% plasmid DNA damage), being as low as 45 μg ml⁻¹ (kitchen) and 100 μg ml⁻¹ (living room), which suggests a high oxidative capacity, with the PM₁₀ generated in kitchens appearing to be the most toxic. The indoor PM₁₀ from the non-smoker's home and outdoor PM₁₀ samples demonstrated high TD₅₀ values and were deemed less bioreactive (i.e. caused limited DNA damage). FESEM observations revealed that four types of particle species were prevalent in Beijing indoor PM₁₀; soot aggregates, minerals, coal fly ash and unknown fine particles. IA showed that higher percentages of soot and unknown fine particles were associated with the lower TD₅₀ values, suggesting that soot and the unknown fine particles may be important components responsible for the observed plasmid DNA damage. The water-soluble trace elements were negatively correlated with the TD₅₀ values, implying that the DNA damage may be attributed to the water-soluble fraction of the PM₁₀. Water-soluble zinc revealed the best relationship with the TD₅₀ values than other analyzed elements, signifying it may play a role in driving the oxidative damage.     

Carbonaceous aerosol characteristics in outdoor and indoor environments of Nanchang, China, during summer 2009

A study of carbonaceous aerosol was initiated in Nanchang, a city in eastern China, for the first time. Daily and diurnal (daytime and nighttime) PM2.5 (particulate matter with aerodynamic diameter < or =2.5 microm) samples were collected at an outdoor site and in three different indoor environments (common office, special printing and copying office, and student dormitory) in a campus of Nanchang University during summer 2009 (5-20 June). Daily PM10 (particulate matter with aerodynamic diameter < or =10 microm) samples were collected only at the outdoor site, whereas PM2.5 samples were collected at both indoor and outdoor sites. Loaded PM2.5 and PM10 samples were analyzed for organic and elemental carbon (OC, EC) by thermal/optical reflectance following the Interagency Monitoring of Protected Visual Environments-Advanced (IMPROVE-A) protocol. Ambient mass concentrations of PM10 and PM2.5 in Nanchang were compared with the air quality standards in China and the United States, and revealed high air pollution levels in Nanchang. PM2.5 accounted for about 70% of PM10, but the ratio of OC and EC in PM2.5 to that in PM10 was higher than 80%, which indicated that OC and EC were mainly distributed in the fine particles. The variations of carbonaceous aerosol between daytime and nighttime indicated that OC was released and formed more rapidly in daytime than in nighttime. OC/EC ratios were used to quantify secondary organic carbon (SOC). The differences in SOC and SOC/OC between daytime and nighttime were useful in interpreting the secondary formation mechanism. The results of (1) OC and EC contributions to PM2.5 at indoor sites and the outdoor site; (2) indoor-outdoor correlation of OC and EC; (3) OC-EC correlation; and (4) relative contributions of indoor and outdoor sources to indoor carbonaceous aerosol indicated that OC indoor sources existed in indoor sites, with the highest OC emissions in I2 (the special printing and copying office), and that indoor EC originated from outdoor sources. The distributions of eight carbon fractions in emissions from the printer and copier showed obviously high OC1 (>20%) and OC2 (approximately 30%), and obviously low EC1-OP (a pyrolyzed carbon fraction) (<10%), when compared with other sources.     

Characterizing and predicting coarse and fine particulates in classrooms located close to an urban roadway

The PM₁₀, PM_2.5, and PM₁ (particulate matter with aerodynamic diameters <10, <2.5, and <1 μm, respectively) concentrations were monitored over a 90-day period in a naturally ventilated school building located at roadside in Chennai City. The 24-hr average PM₁₀, PM_2.5, and PM₁ concentrations at indoor and outdoor environments were found to be 136 ± 60, 36 ± 15, and 20 ± 12 and 76 ± 42, 33 ± 16, and 23 ± 14 μg/m³, respectively. The size distribution of PM in the classroom indicated that coarse mode was dominant during working hours (08:00 a.m. to 04:00 p.m.), whereas fine mode was dominant during nonworking hours (04:00 p.m. to 08:00 a.m.). The increase in coarser particles coincided with occupant activities in the classrooms and finer particles were correlated with outdoor traffic. Analysis of indoor PM₁₀, PM_2.5, and PM₁ concentrations monitored at another school, which is located at urban reserved forest area (background site) indicated 3–4 times lower PM₁₀ concentration than the school located at roadside. Also, the indoor PM₁ and PM_2.5 concentrations were 1.3–1.5 times lower at background site. Further, a mass balance indoor air quality (IAQ) model was modified to predict the indoor PM concentration in the classroom. Results indicated good agreement between the predicted and measured indoor PM_2.5 (R² = 0.72–0.81) and PM₁ (R² = 0.81–0.87) concentrations. But, the measured and predicted PM₁₀ concentrations showed poor correlation (R² = 0.17–0.23), which may be because the IAQ model could not take into account the sudden increase in PM₁₀ concentration (resuspension of large size particles) due to human activities.

Implications:The present study discusses characteristics of the indoor coarse and fine PM concentrations of a naturally ventilated school building located close to an urban roadway and at a background site in Chennai City, India. The study results will be useful to engineers and policymakers to prepare strategies for improving the IAQ inside classrooms. Further, this study may help in the development of IAQ standards and guidelines in India.     

PM2.5 carbon measurements in two urban areas: Seoul and Kwangju,Korea

24-h PM_2.5 carbonaceous samples were collected between 27 November and 9 December 1999 in Seoul, and between 7 and 20 June 2000 in Kwangju to investigate characteristics of carbonaceous species, and the relationship between elemental carbon (EC) and Aethalometer-based black carbon (BC) measurements. 5-min PM_2.5 BC and criteria air pollutant data were also measured using the Aethalometer and ambient air monitoring system. The PM_2.5 samples were analyzed for EC and OC using a selective thermal manganese dioxide oxidation (TMO) method. The daily average EC and OC concentrations in Seoul were higher in the winter than in the summer (Atmos. Environ. 35 (2001a) 657). It was found that difference between ambient BC levels in the two cities was not directly proportional to the population ratio (∼8) or diesel traffic ratio (∼5.9) since particulate matter or BC concentration is strongly influenced by a result of varying traffic and meteorological conditions at the site. Using the primary OC/EC ratio approach, the results suggest that most of the measured OC in Kwangju is of primary origin during the summer. In Seoul, the observed OC includes additional secondary organic aerosol during the wintertime conditions. The relationship between the 24-h TMO-EC and Aethalometer BC measurements in PM_2.5 reflected very good agreement for the two urban sites, with correlation coefficients of R²=0.99 and 0.92, and BC/EC slopes of 0.93 and 1.07, respectively. It was found that comparing TMO-EC to BC at a different location in Korea, a different scaling factor was needed.     

Investigation of PM2.5 and carbon dioxide levels in urban homes

PM_2.5 (particulate matter with an aerodynamic diameter <2.5 μm) samples were collected in the indoor environments of 15 urban homes and their adjacent outdoor environments in Alexandria, Egypt, during the spring time. Indoor and outdoor carbon dioxide (CO₂) levels were also measured concurrently. The results showed that indoor and outdoor PM_2.5 concentrations in the 15 sites, with daily averages of 45.5 ± 11.1 and 47.3 ± 12.9 µg/m³, respectively, were significantly higher than the ambient 24-hr PM_2.5 standard of 35 µg/m³ recommended by the U.S. Environmental Protection Agency (EPA). The indoor PM_2.5 and CO₂ levels were correlated with the corresponding outdoor levels, demonstrating that outdoor convection and infiltration could lead to direct transportation indoors. Ventilation rates were also measured in the selected residences and ranged from 1.6 to 4.5 hr^?1 with median value of 3.3 hr^?1. The indoor/outdoor (I/O) ratios of the monitored homes varied from 0.73 to 1.65 with average value of 0.99 ± 0.26 for PM_2.5, whereas those for CO₂ ranged from 1.13 to 1.66 with average value of 1.41 ± 0.15. Indoor sources and personal activities, including smoking and cooking, were found to significantly influence indoor levels.

Implications: Few studies on indoor air quality were carried out in Egypt, and the scarce data resulted from such studies do not allow accurate assessment of the current situation to take necessary preventive actions. The current research investigates indoor levels of PM_2.5 and CO₂ in a number of homes located in the city of Alexandria as well as the potential contribution from both indoor and outdoor sources. The study draws attention of policymakers to the importance of the establishment of national indoor air quality standards to protect human health and control air pollution in different indoor environments.     

Binational school-based monitoring of traffic-related air pollutants in El Paso, Texas (USA) and Ciudad Juárez, Chihuahua (México)

Paired indoor and outdoor concentrations of fine and coarse particulate matter (PM), PM2.5 reflectance [black carbon(BC)], and nitrogen dioxide (NO₂) were determined for sixteen weeks in 2008 at four elementary schools (two in high and two in low traffic density zones) in a U.S.-Mexico border community to aid a binational health effects study. Strong spatial heterogeneity was observed for all outdoor pollutant concentrations. Concentrations of all pollutants, except coarse PM, were higher in high traffic zones than in the respective low traffic zones. Black carbon and NO₂ appear to be better traffic indicators than fine PM. Indoor air pollution was found to be well associated with outdoor air pollution, although differences existed due to uncontrollable factors involving student activities and building/ventilation configurations. Results of this study indicate substantial spatial variability of pollutants in the region, suggesting that children’s exposures to these pollutants vary based on the location of their school.     

Personal exposure to PM2.5 and element composition—A comparison between outdoor and indoor workers from two Mexican cities

Many individuals work outdoors in the formal and informal economy of the large urban areas in developing countries, where they are potentially exposed for long periods to high concentrations of ambient airborne particulate matter (PM). This study describes the personal exposures to PM of 2.5 μm aerodynamic diameter and smaller (PM_2.5) for a sample of outdoor and indoor workers in two cities, Mexico City and Puebla, in central Mexico.Thirty-six workers in Mexico City and 17 in Puebla were studied. Thirty were outdoor workers (i.e., taxi and bus drivers, street vendors, and vehicle inspectors) and 23 were indoor (office) workers. Their personal exposures to PM_2.5 were monitored for a mean 19-h period. In Mexico City, the street vendors and taxi drivers overall exposures were significantly higher than indoor workers were. In Puebla, bus drivers had a higher overall exposure than vehicle inspectors or indoor workers. Most of the exposures were above the 65 μg m⁻³ 24-h Mexican standard.In Mexico City, exposures to Si, Ti, Cr, Mn, Fe, Ni, Cu, Mo and Cd were higher for outdoor than for indoor workers. In Puebla, exposures to Si, S, K, Ca, Ti, V, Mn, and Zn also were higher for outdoor workers. In Mexico City outdoor workers exposures to Cu, Pb, Cr, Se and Mo were 4 or more times higher than for Puebla outdoor workers, while Puebla outdoor workers’ exposures to V, Si, Fe and Ca were 3 or more times higher than Mexico City outdoor workers.These results suggest that for these outdoor workers the elevated local ambient air PM concentrations and an extended period spent outside are more important contributors to total exposures than indoor concentrations. These workers could be at particular risk of increased morbidity and mortality associated with ambient PM.     

Day-to-Day Particulate Exposures and Health Changes in Los Angeles Area Residents with Severe Lung Disease

ABSTRACT

We measured particulate matter (PM_2.5 and PM₁₀) exposures, home temperature, arterial blood oxygen saturation, blood pressure, and lung function in 30 volunteer Los Angeles area residents during four-day intervals. Continuous Holter electrocardiograms were recorded in a subgroup on the first two days. Subjects recorded symptoms and time-activity patterns in diaries during monitoring, and during a reference period one week earlier/later. All subjects had severe chronic obstructive pulmonary disease. PM₁₀ (24-hr mean) at monitoring stations near subjects’ homes averaged 33 μg/m³, and ranged from 9 to 84 μpg/m³. In longitudinal analyses, day-to-day changes in PM_2.5 and PM₁₀ outside subjects’ homes significantly tracked concurrent station PM10 (r² = 0.22 and 0.44, respectively). Indoor and personal concentrations were less related to station readings (r² ≤ 0.1), but tracked each other (r² ≥ 0.4). In-home temperatures tracked outdoor temperatures more for lows (r² = 0.27) than for highs (r² = 0.10). These longitudinal relationships of subject-oriented and station PM measurements were generally similar to cross-sectional relationships observed previously in similar subjects. Among health measurements, only blood pressure showed reasonably consistent unfavorable longitudinal associations with particulates, more with station or outdoor PM than with indoor or personal PM.     

Inorganic and carbonaceous components in indoor/outdoor particulate matter in two residential houses in Oslo, Norway

A detailed analysis of indoor/outdoor physicochemical aerosol properties has been performed. Aerosol measurements were taken at two dwellings, one in the city center and the other in the suburbs of the Oslo metropolitan area, during summer/fall and winter/spring periods of 2002-2003. In this paper, emphasis is placed on the chemical characteristics (water-soluble ions and carbonaceous components) of fine (PM2.5) and coarse (PM2.5-10) particles and their indoor/outdoor relationship. Results demonstrate that the carbonaceous species were dominant in all fractions of the PM10 particles (cut off size: 0.09-11.31 microm) during all measurement periods, except winter 2003, when increased concentrations of water-soluble inorganic ions were predominant because of sea salt transport. The concentration of organic carbon was higher in the fine and coarse PM10 fractions indoors, whereas elemental carbon was higher indoors only in the coarse fraction. In regards to the carbonaceous species, local traffic and secondary organic aerosol formation were, probably, the main sources outdoors, whereas indoors combustion activities such as preparation of food, burning of candles, and cigarette smoking were the main sources. In contrast, the concentrations of water-soluble inorganic ions were higher outdoors than indoors. The variability of water-soluble inorganic ion concentrations outdoors was related to changes in emissions from local anthropogenic sources, long-range transport of particles, sea salt emissions, and resuspension of roadside and soil dusts. In the indoor environment the infiltration of the outdoor air indoors was the major source of inorganic ions.     

Seasonal and spatial trends in the sources of fine particle organic carbon in Israel,Jordan, and Palestine

A study of carbonaceous particulate matter (PM) was conducted in the Middle East at sites in Israel, Jordan, and Palestine. The sources and seasonal variation of organic carbon, as well as the contribution to fine aerosol (PM_2.5) mass, were determined. Of the 11 sites studied, Nablus had the highest contribution of organic carbon (OC), 29%, and elemental carbon (EC), 19%, to total PM_2.5 mass. The lowest concentrations of PM_2.5 mass, OC, and EC were measured at southern desert sites, located in Aqaba, Eilat, and Rachma. The OC contribution to PM_2.5 mass at these sites ranged between 9.4% and 16%, with mean annual PM_2.5 mass concentrations ranging from 21 to 25 ug m^?3. These sites were also observed to have the highest OC to EC ratios (4.1–5.0), indicative of smaller contributions from primary combustion sources and/or a higher contribution of secondary organic aerosol. Biomass burning and vehicular emissions were found to be important sources of carbonaceous PM in this region at the non-southern desert sites, which together accounted for 30%–55% of the fine particle organic carbon at these sites. The fraction of measured OC unapportioned to primary sources (1.4 μgC m^?3 to 4.9 μgC m^?3; 30%–74%), which has been shown to be largely from secondary organic aerosol, is relatively constant at the sites examined in this study. This suggests that secondary organic aerosol is important in the Middle East during all seasons of the year.     

Comparison of Short-Term Variations (15-Minute Averages) in Outdoor and Indoor PM2.5 Concentrations

ABSTRACT

Measurements of 15-min average PM_2.5 concentrations were made with a real-time light-scattering instrument at both outdoor (central monitoring sites in three communities) and indoor (residential) locations over two seasons in the Minneapolis-St. Paul metropolitan area. These data are used to examine within-day variability of PM_2.5 concentrations indoors and outdoors, as well as matched indoor-to-outdoor (I/O) ratios. Concurrent gravimetric measurements of 24-hr average PM_2.5 concentrations were also obtained as a way to compare real-time measures with this more traditional metric. Results indicate that (1) within-day variability for both indoor and outdoor 15-min average PM_2.5 concentrations was substantial and comparable in magnitude to day-to-day variability for 24hr average concentrations; (2) some residences exhibited substantial variability in indoor aerosol characteristics from one day to the next; (3) peak values for indoor short-term (15-min) average PM_2.5 concentrations routinely exceeded 24-hr average outdoor values by factors of 3-4; and (4) relatively strong correlations existed between indoor and outdoor PM_2.5 concentrations for both 24-hr and 15-min averages.