Indoor Black Carbon Concentrations Research Articles

Implications of fuel poverty for indoor black carbon concentrations from space heating

Despite the global transition towards cleaner energy sources observed over the last decade, disparities in access persist worldwide. The dependence on biomass for household heating exacerbates fuel poverty, as economically vulnerable households face challenges in obtaining certified firewood and often resort to using contaminated biomass as a substitute, either partially or completely. We examined black carbon (BC) particle concentrations —a marker for combustion— during wood stove operation through a five-day case study in a typical Chilean household. BC increased rapidly following the ignition of the stove, with the combustion of dry Eucalyptus globulus logs yielding a substantially lower peak (5.29 μg/m3) than when using unclean biomass: 35.75 μg/m3 with demolition wood and painted furniture, and 87.11 μg/m3 with the addition of a blend of particleboard with polystyrene foam. During the latter two events, BC particles remained indoors for about 20 h before the concentrations reverted to pre-spike levels. The slow decay in BC concentrations was further influenced by the infiltration of outdoor air. The mean indoor BC concentrations were comparable to or even exceeded those observed on busy roads in major cities worldwide. These results highlight the risks associated with limited access to clean fuels for indoor heating, alongside inadequate insulation. This study sheds light on the problem of fuel poverty and its adverse effects on health and well-being.

Measuring and modeling of residential black carbon concentrations in two megacities, China

Indoor exposure to black carbon (BC) may differ greatly from ambient concentrations measured at stationary monitoring stations. This study characterized the variation between measured indoor and outdoor levels of BC and developed models to predict BC exposures within residences. Indoor and outdoor PM2.5 filter samples were collected for five consecutive days from 66 residences in Beijing (BJ) and Nanjing (NJ), China, across two seasons. City-specific indoor BC models were developed using liner mixed effect models and assessed by R2 and root mean square error (RMSE). The mean (SD) of indoor BC concentrations in BJ and NJ were 3.0 μg/m3 (0.6 μg/m3) and 3.2 μg/m3 (0.5 μg/m3), respectively. Both the indoor and outdoor BC concentrations were significantly higher during heating season than non-heating season. In general, indoor levels of BC were strongly associated with outdoor measurements (BJ: rs = 0.74, p < 0.001; NJ: rs = 0.76, p < 0.001), but were often lower. The critical determinants influencing indoor BC exposures varied by city, including outdoor BC concentration, window opening time, presence of indoor smoking, and the volume of the room where the indoor monitor was placed. The final models accounted for 66.4%–86.5 % (RMSE: 0.070–0.106) of the variance in residential-indoor BC exposures. By incorporating the key BC exposure determinants identified here, this modelling approach can improve the estimates of BC exposure and better link BC exposure to health risk assessment.

Comparison of measured residential black carbon levels outdoors and indoors with fixed-site monitoring data and with dispersion modelling

Epidemiologic studies on health effects of air pollution usually rely on time-series of ambient monitoring data or on spatially modelled levels. Little is known how well these estimate residential outdoor and indoor levels. We investigated the agreement of measured residential black carbon (BC) levels outdoors and indoors with fixed-site monitoring data and with levels calculated using a Gaussian dispersion model. One-week residential outdoor and indoor BC measurements were conducted for 15 families living in central Stockholm. Time-series from urban background and street-level monitors were compared to these measurements. The observed weekly concentrations were also standardized to reflect annual averages, using urban background levels, and compared spatially to long-term levels as estimated by dispersion modelling. Weekly average outdoor BC level was 472 ng/m3 (range 261–797 ng/m3). The corresponding fixed-site urban background and street levels were 313 and 1039 ng/m3, respectively. Urban background variation explained 50% of the temporal variation in residential outdoor levels averaged over 24 h. Modelled residential long-term outdoor levels were on average comparable with the standardized measured home outdoor levels, and explained 49% of the spatial variability. The median indoor/outdoor ratio across all addresses was 0.79, with no difference between day and night time. Common exposure estimation approaches in the epidemiology of health effects related to BC displayed high validity for residencies in central Stockholm. Urban background monitored levels explained half of the outdoor day-to-day variability at residential addresses. Long-term dispersion modelling explained half of the spatial differences in outdoor levels. Indoor BC concentrations tended to be somewhat lower than outdoor levels.

Developing a predictive model for indoor black carbon for the Denver, CO metropolitan area

PDS 65: Exposure assessment: implications for epidemiology, Exhibition Hall (PDS), Ground floor, August 27, 2019, 1:30 PM - 3:00 PM Background: Though individuals spend ~90% of their time indoors, ambient air pollution data are frequently used in exposure assessment for epidemiologic studies. We sought to understand the relation between indoor and outdoor concentrations of black carbon (BC) and additional housing characteristics associated with indoor BC concentrations among cohort study participants in Denver, CO. Methods: Households from the Healthy Start cohort were selected for monitoring based on diversity in housing type and built environmental characteristics. For one week in spring and summer 2018, households were provided two low-cost air samplers, one for outdoor and one for indoor measurement. Participants completed questionnaires addressing housing specifics such as building type, flooring, and use of heating and cooling systems. BC was measured using transmissometry and weekly mean concentrations were log transformed prior to model fitting. A linear model was fit using all available predictors obtained from surveys as well as outdoor BC concentrations. Model selection was performed using stepwise backwards elimination; model fit was evaluated using AIC. Results: A total of 25 households participated in the study: 11 filters had BC measurements below LOD, and data were available for 39 filters. The average (SD) indoor and outdoor concentrations were 1.1 (0.8) and 1.2 (0.6) μg/m3, respectively. Outdoor BC concentrations were significant predictors of log(indoor BC) in a single-predictor model (β = 0.49, p = 0.02, R2=0.12). The final model included outdoor BC, single family home, tile flooring, and use of electric heater and had an adjusted R2 of 0.5. Conclusion: Outdoor BC and housing characteristics were able to account for ~50% of the variability in indoor BC concentrations measured in Denver, CO homes. In the absence of personal monitoring, household characteristics and time-activity patterns may be used in calibrating ambient air pollution concentrations for personal exposure estimation.

Assessment of black carbon concentration as a potential measure of air quality at multi-purpose facilities

Despite its potential adverse health effects, black carbon (BC) has not received much attention from the perspective of managing indoor air quality at multi-purpose facilities. In this scenario, real-time measurements of indoor BC were performed in a classroom, in parking lots, and in airplane cabins. Results showed that the average typical indoor BC concentration in a classroom is approximately 1 μg/m³, which is comparable to a typical ambient BC concentration. The indoor and ambient BC concentrations were simultaneously measured using two microAeth AE51s. The indoor BC concentrations varied during the experiments depending on the ambient BC concentrations, suggesting that both indoor and ambient concentrations show site- and/or source-specific correlative responses. The highest BC concentration was observed in parking lots, and it instantaneously reached 39 μg/m3. Our approach has important advantages for certain tasks such as the identification of hotspots and the monitoring of variations in BC concentrations as a supplementary tool.

Predicting indoor concentrations of black carbon in residential environments

Black carbon (BC) is a descriptive term that refers to light-absorbing particulate matter (PM) produced by incomplete combustion and is often used as a surrogate for traffic-related air pollution. Exposure to BC has been linked to adverse health effects. Penetration of ambient BC is typically the primary source of indoor BC in the developed world. Other sources of indoor BC include biomass and kerosene stoves, lit candles, and charring food during cooking. Home characteristics can influence the levels of indoor BC. As people spend most of their time indoors, human exposure to BC can be associated to a large extent with indoor environments. At the same time, due to the cost of environmental monitoring, it is often not feasible to directly measure BC inside multiple individual homes in large-scale population-based studies. Thus, a predictive model for indoor BC is needed to support risk assessment in public health. In this study, home characteristics and occupant activities that potentially modify indoor levels of BC were documented in 23 homes, and indoor and outdoor BC concentrations were measured twice. The homes were located in the Cincinnati-Kentucky-Indiana tristate region and measurements occurred from September 2015 through August 2017. A linear mixed-effect model was developed to predict BC concentration in residential environments. The measured outdoor BC concentrations and the documented home characteristics were utilized as predictors of indoor BC concentrations. After the model was developed, a leave-one-out cross-validation algorithm was deployed to assess the predictive accuracy of the output. The following home characteristics and occupant activities significantly modified the concentration of indoor BC: outdoor BC, lit candles and electrostatic or high efficiency particulate air (HEPA) filters in heating, ventilation and air conditioning (HVAC) systems. Predicted indoor BC concentrations explained 78% of the variability in the measured indoor BC concentrations. The data show that outdoor BC combined with home characteristics can be used to predict indoor BC levels with reasonable accuracy.

Cardiovascular benefits of short-term indoor air filtration intervention in elderly living in Beijing: An extended analysis of BIAPSY study

BackgroundAdverse cardiovascular effects associated with air pollution exposure have been widely demonstrated. However, inconsistent cardiovascular responses were observed from reducing indoor air pollution exposure. We aimed to assess whether short-term air filtration intervention could benefit cardiovascular health in elderly living in high pollution area. MethodsA randomized crossover intervention study of short-term indoor air filtration intervention on cardiovascular health was conducted among 35 non-smoking elderly participants living in Beijing in the winter of 2013, as part of Beijing Indoor Air Purifier StudY (BIAPSY). Portable air filtration units were randomly allocated to active filtration for 2 weeks and sham filtration for 2 weeks in the households. Twelve-hour daytime ambulatory heart rate variability (HRV) and blood pressure (ABP) were measured during active and sham filtration. Concurrently, real-time indoor and outdoor particulate matter with diameter less than 2.5 µm (PM2.5) and indoor black carbon (BC) concentrations were measured. We applied generalized additive mixed models to evaluate the associations of 1- to 10-h moving average (MA) exposures of indoor PM2.5 and BC with HRV and ABP indices, and to explore whether these associations could be modified by air filtration. ResultsWe observed decreases of 34.8% in indoor PM2.5 and 35.3% in indoor BC concentrations during active filtration. Indoor PM2.5 and BC exposures were significantly associated with reduced HRV and increased ABP indices, and greater changes were observed during sham filtration. In specific, each 10 μg/m3 increase in indoor PM2.5 at MA8-h was associated with a significant reduction of 1.34% (95% CI: −2.42, −0.26) in SDNN during sham filtration, compared with a non-significant reduction of 0.81% (95% CI: −6.00, 4.68) during active filtration (Pinter< 0.001). Each 1 μg/m3 increase in indoor BC at MA8-h was associated with a significant increase of 2.41% (95% CI: 0.38, 4.47) in SBP during sham filtration, compared with a non-significant increase of −1.09% (95% CI: −4.06, 1.96) during active filtration (Pinter = 0.135). Nonlinear inverse exposure-response relationships of indoor air pollution exposures with predicted HRV and ABP indices also confirmed some cardiovascular benefits of short-term air filtration intervention. ConclusionsOur results suggested that short-term indoor air filtration intervention can be of some cardiovascular benefits in elderly living with high pollution episodes.

Exploratory assessment of outdoor and indoor airborne black carbon in different locations of Hanoi, Vietnam

Black carbon (BC) is a significant component of atmospheric particulate matter, especially in areas affected by combustion emissions. Despite the fact that air pollution is a great concern in Vietnam, there are no studies on the level of BC in the outdoor and indoor environment. In this exploratory study, an assessment of urban BC concentrations was conducted through monitoring of both outdoor and indoor BC concentrations in three households and one working office at different locations across Hanoi. PM2.5 and meteorology data were also obtained for this monitoring period to evaluate the association between them and the outdoor BC concentration. Overall, the mean indoor and mean outdoor BC concentrations by 30 second-logs for the monitoring period were 4.42 μg/m3 and 4.89 μg/m3, respectively. Time-series analysis of paired indoor and outdoor BC concentrations suggested that indoor BC level was usually influenced by outdoor BC level (r = 0.78, p < 0.001). In this study, we observed a significant positive association between outdoor BC and PM2.5 (r = 0.39, p < 0.001) while outdoor BC negatively correlated with wind speed (r = −0.34, p < 0.001). The level of outdoor BC in Hanoi measured in this study is relatively high and should be confirmed by further studies.

Ultrafine, fine, and black carbon particle concentrations in California child-care facilities.

Although many U.S. children spend time in child care, little information exists on exposures to airborne particulate matter (PM) in this environment, even though PM may be associated with asthma and other respiratory illness, which is a key concern for young children. To address this data gap, we measured ultrafine particles (UFP), PM2.5 , PM10 , and black carbon in 40 California child-care facilities and examined associations with potential determinants. We also tested a low-cost optical particle measuring device (Dylos monitor). Median (interquartile range) concentrations for indoor UFP, gravimetric PM2.5 , real-time PM2.5 , gravimetric PM10 , and black carbon over the course of a child-care day were 14000 (11000-29000) particles/cm3 , 15 (9.6-21) μg/m3 , 15 (11-23) μg/m3 , 48 (33-73) μg/m3 , and 0.43 (0.25-0.65) ng/m3 , respectively. Indoor black carbon concentrations were inversely associated with air exchange rate (Spearman's rho=-.36) and positively associated with the sum of all Gaussian-adjusted traffic volume within a one-kilometer radius (Spearman's rho=.45) (P-values <.05). Finally, the Dylos may be a valid low-cost alternative to monitor PM levels indoors in future studies. Overall, results indicate the need for additional studies examining particle levels, potential health risks, and mitigation strategies in child-care facilities.

Indoor air quality in green-renovated vs. non-green low-income homes of children living in a temperate region of US (Ohio)

Green eco-friendly housing includes approaches to reduce indoor air pollutant sources and to increase energy efficiency. Although sealing/tightening buildings can save energy and reduce the penetration of outdoor pollutants, an adverse outcome can be increased buildup of pollutants with indoor sources. The objective of this study was to determine the differences in the indoor air quality (IAQ) between green and non-green homes in low-income housing complexes. In one housing complex, apartments were renovated using green principles (n=28). Home visits were conducted immediately after the renovation, and subsequently at 6months and at 12months following the renovation. Of these homes, eight homes had pre-renovation home visits; this allowed pre- and post-renovation comparisons within the same homes. Parallel visits were conducted in non-green (control) apartments (n=14) in a nearby low-income housing complex. The IAQ assessments included PM2.5, black carbon, ultrafine particles, sulfur, total volatile organic compounds (VOCs), formaldehyde, and air exchange rate. Data were analyzed using linear mixed-effects models. None of the indoor pollutant concentrations were significantly different between green and non-green homes. However, we found differences when comparing the concentrations before and after renovation. Measured immediately after renovation, indoor black carbon concentrations were significantly lower averaging 682ng/m3 in post-renovation vs. 2364ng/m3 in pre-renovation home visits (p=0.01). In contrast, formaldehyde concentrations were significantly higher in post-renovated (0.03ppm) than in pre-renovated homes (0.01ppm) (p=0.004). Questionnaire data showed that opening of windows occurred less frequently in homes immediately post-renovation compared to pre-renovation; this factor likely affected the levels of indoor black carbon (from outdoor sources) and formaldehyde (from indoor sources) more than the renovation status itself. To reduce IAQ problems and potentially improve health, careful selection of indoor building materials and ensuring sufficient ventilation are important for green building designs.

Reductions in indoor black carbon concentrations from improved biomass stoves in rural India.

Deployment of improved biomass burning cookstoves is recognized as a black carbon (BC) mitigation measure that has the potential to achieve health benefits and climate cobenefits. Yet, few field based studies document BC concentration reductions (and resulting human exposure) resulting from improved stove usage. In this paper, data are presented from 277 real-world cooking sessions collected during two field studies to document the impacts on indoor BC concentrations inside village kitchens as a result of switching from traditional stoves to improved forced draft (FD) stoves. Data collection utilized new low-cost cellphone methods to monitor BC, cooking duration, and fuel consumption. A cross sectional study recorded a reduction of 36% in BC during cooking sessions. An independent paired sample study demonstrated a statistically significant reduction of 40% in 24 h BC concentrations when traditional stoves were replaced with FD stoves. Reductions observed in these field studies differ from emission factor reductions (up to 99%) observed under controlled conditions in laboratory studies. Other nonstove sources (e.g., kerosene lamps, ambient concentrations) likely offset the reductions. Health exposure studies should utilize reductions determined by field measurements inside village kitchens, in conjunction with laboratory data, to assess the health impacts of new cooking technologies.

Addressing the Burden of Disease Attributable to Air Pollution in India: The Need to Integrate across Household and Ambient Air Pollution Exposures

Addressing the Burden of Disease Attributable to Air Pollution in India: The Need to Integrate across Household and Ambient Air Pollution Exposures

Dimensional and Chemical Characterization of Airborne Particles in Schools: Respiratory Effects in Children

This work reports the detailed characterization of child exposure to particles in three naturally-ventilated Italian schools. Two polluted urban schools and a rural one are considered in this study. Dimensional and chemical analyses of particles were performed by measuring particle number concentrations, particle size distributions, OC/BC concentrations and relative inorganic and organic fractions, both indoors and outdoors.Respiratory function, exhaled Nitric Oxide (eNO) and Prick Skin tests were also performed on 75 children attending the three schools in order to evaluate the effects of such exposure on the children’s respiratory systems. Exposure to particles at the urban schools was found higher than at the rural one, from both dimensional and chemical perspectives. Indoor particle number concentrations ranged from 1.95 × 104 to 3.49 × 104 part./cm3, whereas indoor black carbon concentrations varied between 1.9–13.9 μg/m3, with the lowest levels of both measured at the rural school.In contrast to the dimensional and chemical results, the respiratory function and eNO test results were statistically similar among children attending all the three schools: the lung function values were within 20% of the European Community for Steel and Coal predicted ones, with the eNO data for healthy children ranging from 10.1 to 11.5 ppm. Medical outcomes indicate that these levels of school exposure did not significantly affect the children’s respiratory outcomes.

Black carbon emissions from biomass and fossil fuels in rural India

Abstract. Black carbon (BC) emission from biofuel cooking in South Asia and its radiative forcing is a significant source of uncertainty for health and climate impact studies. Quantification of BC emissions in the published literature is either based on laboratory or remote field observations far away from the source. For the first time under Project Surya, we use field measurements taken simultaneously inside rural households, ambient air and vehicular emissions from highways in a rural area in the Indo-Gangetic-Plains region of India to establish the role of both solid biomass based cooking in traditional stoves and diesel vehicles in contributing to high BC and organic carbon (OC), and solar absorption. The major finding of this study is that BC concentrations during cooking hours, both indoors and outdoors, have anomalously large twice-daily peak concentrations reaching 60 μg m−3 (median 15-min average value) for indoor and 30 μg m−3 (median 15-min average value) for outdoor during the early morning (05:00 to 08:00) and early evening (17:00 to 19:00) hours coinciding with the morning and evening cooking hours. The BC during the non-cooking hours were also large, in the range of 2 to 30 μg m−3. The peak indoor BC concentrations reached as high as 1000 μg m−3. The large diurnal peaks seen in this study lead to the conclusion that satellite based aerosol studies that rely on once- daily daytime measurements may severely underestimate the BC loading of the atmosphere. The concentration of OC was a factor of 5 larger than BC and furthermore optical data show that absorbing brown carbon was a major component of the OC. The imprint of the cooking hour peaks were seen in the outdoor BC both in the village as well as in the highway. The results have significant implications for climate and epidemiological studies.

Workplace exposure to traffic-derived nanoscaled particulates

Workplace exposure to traffic-derived nanoscaled particulates was determined at a chemical research facility. Sub-micron particles were monitored by means of a multi-angle absorption photometer (MAAP) and a laser spectrometer (GRIMM 1107), providing 10-minute black carbon (BC) concentrations and 15-minute PM1 concentrations, respectively, over a 4-month period (22/03/2010 – 28/07/2010). BC levels were simultaneously monitored during 1-day periods using a handheld aethalometer (Magee AE51), with excellent agreement between both techniques (MAAP and AE51, r2 = 0.96, y = 0.84x).The studied laboratory is located on the 5th floor of an 8-storey building in an urban background environment in Barcelona, Spain. The laboratory was not in use during the study period, and both of its doors were kept open at all times in order to ensure air circulation between the study laboratory and the remaining offices and laboratories on the same floor (where workers were exposed). Windows were kept closed at all times. Indoor BC and PM1 concentrations were compared with ambient BC and PM1 levels from an outdoor monitoring station located at <150 m away from the research facility. Results evidenced the major impact of outdoor vehicular traffic emissions on the levels of nanoscale particulates monitored in the workplace, with clear daily cycles coinciding with traffic rush hours, especially during week days. Penetration ratios were calculated for BC which showed that, even ensuring that all windows were closed, at least 82% of indoor BC concentrations originate from outdoor emissions. Outdoor/indoor penetration ratios were stable for BC (ranging between 1.20 and 1.35) but not for PM1 (1.76 to 1.02), suggesting that it is necessary to monitor the variability of penetration factors as a function of time. BC emission sources in the workplace still need to be determined, but could be related to printer/photocopier toner emissions and laboratory work. Potential contamination due to the monitoring instruments (pumps) was discarded through the analysis of daily indoor BC cycles.

Effects of Floor Level and Building Type on Residential Levels of Outdoor and Indoor Polycyclic Aromatic Hydrocarbons, Black Carbon, and Particulate Matter in New York City

Consideration of the relationship between residential floor level and concentration of traffic-related airborne pollutants may predict individual residential exposure among inner city dwellers more accurately. Our objective was to characterize the vertical gradient of residential levels of polycyclic aromatic hydrocarbons (PAH; dichotomized into Σ(8)PAH(semivolatile) (MW 178-206), and Σ(8)PAH(nonvolatile) (MW 228-278), black carbon (BC), PM(2.5) (particulate matter) by floor level (FL), season and building type. We hypothesize that PAH, BC and PM(2.5) concentrations may decrease with higher FL and the vertical gradients of these compounds would be affected by heating season and building type. PAH, BC and PM(2.5) were measured over a two-week period outdoor and indoor of the residences of a cohort of 5-6 year old children (n = 339) living in New York City's Northern Manhattan and the Bronx. Airborne-pollutant levels were analyzed by three categorized FL groups (0-2nd, 3rd-5th, and 6th-32nd FL) and two building types (low-rise versus high-rise apartment building). Indoor Σ(8)PAH(nonvolatile) and BC levels declined with increasing FL. During the nonheating season, the median outdoor Σ(8)PAH(nonvolatile,) but not Σ(8)PAH(semivolatile), level at 6th-2nd FL was 1.5-2 times lower than levels measured at lower FL. Similarly, outdoor and indoor BC concentrations at 6th-32nd FL were significantly lower than those at lower FL only during the nonheating season (p < 0.05). In addition, living in a low-rise building was associated significantly with higher levels of Σ(8)PAH(nonvolatile) and BC. These results suggest that young inner city children may be exposed to varying levels of air pollutants depending on their FL, season, and building type.

A Comparative Study of the Main Mechanisms Controlling Indoor Air Pollution in Residential Flats

The relative contribution of the main mechanisms that control indoor air quality in residential flats was examined. Indoor and outdoor concentration measurements of different type pollutants (black carbon, SO2, O3, NO, NO2,) were monitored in three naturally ventilated residential flats in Athens, Greece. At each apartment, experiments were conducted during the cold as well as during the warm period of the year. The controlling parameters of transport and deposition mechanisms were calculated from the experimental data. Deposition rates of the same pollutant differ according to the site (different construction characteristics) and to the measuring period for the same site (variations in relative humidity and differences in furnishing). Differences in the black carbon deposition rates were attributed to different black carbon size distributions. The highest deposition rates were observed for O3 in the residential flats with the older construction and the highest humidity levels. The calculated parameters as well as the measured outdoor concentrations were used as input data of a one-compartment indoor air quality model, and the indoor concentrations, the production, and loss rates of the different pollutants were calculated. The model calculated concentrations are in good agreement with the measured values. Model simulations revealed that the mechanism that mainly affected the change rate of indoor black carbon concentrations was the transport from the outdoor environment, while the removal due to deposition was insignificant. During model simulations, it was also established that that the change rate of SO2 concentrations was governed by the interaction between the transport and the deposition mechanisms while NOX concentrations were mainly controlled through photochemical reactions and the transport from outdoors.