Indoor Organic Carbon Research Articles

Comparison of air pollutant emissions and household air quality in rural homes using improved wood and coal stoves

Air pollutant emissions, fuel consumption, and household air pollution were investigated in rural Hubei, central China, as a revisited evaluation of an intervention program to replace coal use by wood in gasifier stoves. Measured emission factors were comparable to the results measured two years ago when the program was initiated. Coal combustion produced significantly higher emissions of CO2, CH4, and SO2 compared with wood combustion; however, wood combustion in gasifier stoves had higher emissions of primary PM2.5 (particles with diameter less than 2.5 μm), Elemental Carbon (EC) and Organic Carbon (OC). In terms of potential impacts on climate, although the use of wood in gasifier stoves produced more black carbon (6.37 vs 910 gCO2e per day per capita from coal and wood use) and less SO2 (-684 vs -312), obvious benefits could be obtained owing to greater OC emissions (-15.4 vs -431), fewer CH4 emissions (865 vs 409) and, moreover, a reduction of CO2 emissions. The total GWC100 (Global Warming Potential over a time horizon of 100 years) would decrease by approximately 90% if coal use were replaced with renewable wood burned in gasifier stoves. However, similar levels of ambient particles and higher indoor OC and EC were found at homes using wood gasifier stoves compared to the coal-use homes. This suggests critical investigations on potential health impacts from the carbon-reduction intervention program.

Trends in indoor–outdoor PM2.5 research: A systematic review of studies conducted during the last decade (2003–2013)

There has been growing concern about potential health risks from exposure to PM2.5 (fine particulate matter). The importance of conducting simultaneous indoor and outdoor measurements emerged because people, especially in developed countries, spend more than 90% of their time indoors. Great spatial and temporal variations in human exposure to PM2.5 have recently been reported. This review aims to identify the main research areas that have attracted recent attention, any possible gaps in the measurements of PM2.5 in various microenvironments, and the relationships between indoor and outdoor concentrations. This study also provides recommendations for further studies on PM2.5 measurement methods and exposure levels. To achieve these goals, this review included articles published online from 2003 to 2013 in the Science Direct and Web of Science databases. In the initial screening stage, 113 abstracts selected while 61 articles were remained for full review. The reviewed studies consistently showed positive correlations between indoor and outdoor PM2.5. Sulfate/sulfur concentrations were used intensively for calculating the infiltration factor (FINF). The higher FINF indicated high infiltration of outdoor PM2.5 into indoor areas. Great percentage (42%) of the reviewed filter–based studies was conducted in Europe, followed by a similar amount (38%) in the USA, and 20% in Asia, indicating a lack in PM2.5 research in other parts of the world. It was difficult to conclude that ambient fixed–site monitoring provided accurate estimations of actual exposure to PM2.5– Studies shown trends of higher personal concentrations compared to indoor and outdoor ones. Higher indoor levels of OC (organic carbon), compared to outdoor levels, were consistently reported. The opposite trend was true for EC (elemental carbon), and there were higher indoor OC/EC ratios than outdoor OC/EC ratios. There was a consistent general trend of a high (r>0.70) correlation between indoor and outdoor EC, while the correlation between indoor and outdoor OC was much weaker (r=022–0.75). The higher indoor OC/EC ratios, compared to the outdoor OC/EC ratios, reflects multiple sources of indoor OC. Sulfate (SO42–), nitrate (NO3–), and ammonium (NH4+) were primary contributors to PM2.5 mass.

Indoor and outdoor suspended particulate matter and associated carbonaceous species at residential homes in northwestern Portugal

Particulate matter with an aerodynamic diameter equal to or less than 10μm (PM10), organic carbon (OC) and elemental carbon (EC) concentrations were measured simultaneously in the indoor and outdoor air of 4 residences located in urban and sub-urban areas in northwestern Portugal. The residences were studied with occupants. One residence was also studied without any indoor activity, taking advantage of the fact that the occupants had moved into a new home. First, 48-h aerosol samples were collected on quartz fiber filters with low-volume samplers equipped with size selective inlets. The filters were weighed and then analyzed for OC and EC using a thermal–optical transmittance method. The average indoor and outdoor PM10 concentrations in the occupied residences were 71.9±38.3μg/m3 and 54.0±13.3μg/m3, respectively. Despite the higher concentration of PM10 indoors, outdoor sources were found to be a significant contributor to indoor concentrations. An estimate based on data from the residence studied under different occupancy conditions indicated that outdoor sources can account for 68% of the indoor PM10 mass concentration. Average indoor to outdoor (I/O) ratios for OC ranged from 1.7 to 5.6 in occupied residences, showing that indoor sources, such as cooking, smoking, biomass burning and movement of people, strongly influenced indoor OC concentrations. In contrast, I/O ratios for EC were close to 1, except for a smokers' residence, suggesting that indoor concentrations were mainly controlled by outdoor sources, most likely from vehicular emissions and biomass burning.

Contribution of Fungal Spores to Organic Carbon Aerosol in Indoor and Outdoor Environments in the Greater Cincinnati Area

Airborne fungi may contribute to the organic carbon (OC) content of particulate matter, which make them relevant to air pollution and climate change issues. This study aimed at assessing the contribution of fungal spores to the inhalable OC in indoor and outdoor environments in the Cincinnati metropolitan area. The contribution was calculated assuming that carbon content per fungal spore was 13 pg (derived from a report from Austria). Air samples were collected from 18 homes during summer. At each site, two air samples were simultaneously taken using Button Personal Inhalable Samplers for 24 hours. One sample was subjected to the total fungi enumeration and the other one was analyzed for OC with ThermalOptical Transmittance technique. A (1-3)-β-d-glucan analysis was also conducted for indoor air samples using Limulus Amebocyte Lysate assay. Additionally, a questionnaire survey was performed on the various factors that might affect the indoor aerosol OC level. The total OC concentration ranged from 0.5 to 19.0 μg/m 3 in outdoor air and from 0 to 36.2 3 in indoor air. The concentration of OC originating from fungal spores ranged from 3.8 to 958.4 ng/m 3 in outdoor air while the respective range in indoor air was 0.8 to 351.2 ng/m 3 . The (1-3)-β-d-glucan was present indoors at levels ranging from 82.1 to 41,910 pg/m 3 . In contrast to studies performed in Austria, Australia and Britain, we found that fungal spores contribute rather little to the local outdoor OC. This could be due to different sampling instruments used for fungal spore sampling and regional differences in fungal spore concentrations. Even smaller contribution of fungal spores was found for indoor OC (average of 0.21%). Statistical analysis revealed that cigarette smoking was a significant factor for the indoor organic carbon level. The results indicate that smoking contributes to the indoor OC level more significantly than fungi.

Chemical Characterization and Source Apportionment of Fine and Coarse Particulate Matter Inside the Refectory of Santa Maria Delle Grazie Church, Home of Leonardo Da Vinci’s “Last Supper”

The association between exposure to indoor particulate matter (PM) and damage to cultural assets has been of primary relevance to museum conservators. PM-induced damage to the "Last Supper" painting, one of Leonardo da Vinci's most famous artworks, has been a major concern, given the location of this masterpiece inside a refectory in the city center of Milan, one of Europe's most polluted cities. To assess this risk, a one-year sampling campaign was conducted at indoor and outdoor sites of the painting's location, where time-integrated fine and coarse PM (PM(2.5) and PM(2.5-10)) samples were simultaneously collected. Findings showed that PM(2.5) and PM(2.5-10) concentrations were reduced indoors by 88 and 94% on a yearly average basis, respectively. This large reduction is mainly attributed to the efficacy of the deployed ventilation system in removing particles. Furthermore, PM(2.5) dominated indoor particle levels, with organic matter as the most abundant species. Next, the chemical mass balance model was applied to apportion primary and secondary sources to monthly indoor fine organic carbon (OC) and PM mass. Results revealed that gasoline vehicles, urban soil, and wood-smoke only contributed to an annual average of 11.2 ± 3.7% of OC mass. Tracers for these major sources had minimal infiltration factors. On the other hand, fatty acids and squalane had high indoor-to-outdoor concentration ratios with fatty acids showing a good correlation with indoor OC, implying a common indoor source.

Factors affecting the indoor concentrations of carbonaceous aerosols of outdoor origin

A field study was conducted in an unoccupied single-story residence in Clovis, California, to provide data to address issues important to assess the indoor exposure to particles of outdoor origin. Measurements of black and organic carbonaceous aerosols were performed using a variety of methods, resulting in both near real-time measurements as well as integrated filter-based measurements. Comparisons of the different measurement methods show that it is crucial to account for gas phase adsorption artifacts when measuring organic carbon (OC). Measured concentrations affected by the emissions of organic compounds sorbed to indoor surfaces imply a higher degree of infiltration of outdoor organic carbon aerosols into the indoor environment for our unoccupied house. Analysis of the indoor and outdoor data for black carbon (BC) aerosols show that, on average, the indoor concentration of black carbon aerosols behaves in a similar manner to sulfate aerosols. In contrast, organic carbon aerosols are subject to chemical transformations indoors that for our unoccupied home, resulted in lower indoor OC concentrations than would be expected by physical loss mechanisms alone. These results show that gas to particle partitioning of organic compounds, as well as gas to surface interactions within the residence, are an important process governing the indoor concentration to OC aerosols of outdoor origin.

Organic and elemental carbon concentrations in fine particulate matter in residences, schoolrooms, and outdoor air in Mira Loma, California

Indoor and outdoor elemental carbon (EC) and organic carbon (OC) concentrations were measured from September 2001 through January 2002 at 20 residential sites and a local high school in western Riverside County, CA. The correlation (R 2 ) between indoor vs. outdoor EC and indoor vs. outdoor OC were 0.63 and 0.47, respectively, while the correlation of EC to OC outdoors and indoors was 0.58 and 0.23, respectively. The average OC content of PM2.5 was 0.25 and 0.55 for outdoor and indoor PM2.5, respectively. It was concluded that there were no significant indoor sources of EC while indoor OC sources contributed significantly to indoor PM2.5. Home with smokers had significantly higher TC and OC than homes without. Schoolrooms generally had less EC and OC due to the schools HVAC system. r 2005 Elsevier Ltd. All rights reserved.

Indoor/outdoor relationships of organic carbon (OC) and elemental carbon (EC) in PM2.5 in roadside environment of Hong Kong

Abstract Five buildings located near roadsides (an office and a classroom with mechanical ventilation (MV) and three residences with natural ventilation (NV)) were selected with a view to characterising indoor and outdoor concentrations of organic (OC) and elemental carbon (EC). PM2.5 samples were analysed using a thermal optical reflectance (TOR) method for OC and EC concentrations. The average 24-h PM2.5 outdoor concentration was 78.4 μg m−3, whilst the average outdoor OC and EC concentrations were 12.6 and 6.4 μg m−3, respectively, accounting for 17% and 9%, respectively of the outdoor PM2.5 mass. The average 24-h PM2.5 indoor concentration was 55.4 μg m−3 of which indoor OC and EC were 11.3 and 4.8 μg m−3, respectively, accounted for 22% and 9%, respectively. The mean value of indoor to outdoor ratios (I/O ratios) of PM2.5 was 0.80, with a close correlation between indoor and outdoor PM2.5 concentrations, especially in the NV residences. The average I/O ratios of OC and EC were 1.02 and 0.80, respectively. The higher ratio for OC reflects indoor sources of OC, which do not appear to occur for EC. The major source of indoor EC, OC and PM2.5, however, appears to be penetration of outdoor air, with a much greater attenuation in the MV buildings studied.