Outdoor Levels Research Articles

A natural ventilation “calculator”: The challenge of defining a representative ‘performance sketch’ in practice and research

Too often in architecture and engineering, the simplicity in early design of the apparent guarantees of HVAC equipment manufacturers wins out over the complexity of estimating the effectiveness of natural ventilation even in Net Zero Buildings. The reality is many people in offices and schools find themselves sitting at a fixed desk, in full direct sun, with the cold draft from the HVAC equipment guaranteeing that on average they are comfortable. The drawing of blinds ‘solves’ the immediate sun problem, but not the quality of the air. Experience with 200+ students designing low energy, high performance naturally ventilated spaces each year over the past decade has demonstrated that the formulae that exist in the literature for early estimation of window opening size have potential if presented in an appropriate format to facilitate sound design decisions. This paper reports the evolution of that format to a calculation dashboard that facilitates accounting for: outdoor and indoor CO2 levels; wind speeds and frequencies of occurrence; coincidence of periods of calm with high outdoor temperatures; window effectiveness coefficients; single-sided vs cross-ventilation options; building shape and orientation; code minimum ventilation rates; and even infiltration. The paper focuses on the limitations of the approach and its potential complementary role in the future as a Quality Assurance tool for critiquing the output of CFD studies of natural ventilation.

Residential indoor pollution by nitrogen dioxide: conference series

According to the Environmental Protection Agency, indoor air quality (IAQ) is defined as air quality within and around buildings and structures and it is related to the health and comfort of building occupants. A better understanding of IAQ is essential, since people spend more than 90 percent of their time indoors. The greatest amount of time spent indoors is at home, so it is important to control indoor air pollution and to reduce the risk of health effects related with indoor air pollutants exposure. The aim of this study was to determine indoor air pollution of nitrogen dioxide (NO2) in different seasons and to compare indoor and outdoor NO2 concentrations. The sampling of NO2 was performed in cold, warm and intermediate seasons using passive sampling technique inside and outside of the residential houses. The results of the study showed that the average NO2 concentration in cold season was 10.5 μg/m3 and 20.0 μg/m3, respectively in indoor and outdoor air. The lowest indoor and outdoor levels of NO2 were observed in warm season, 9.7 and 11.3 μg/m3, respectively. The strongest positive relationship between indoor and outdoor concentrations of NO2 was determined in warm season.

A global perspective on national climate mitigation priorities in the context of air pollution and sustainable development

Air pollution and climate change are key global challenges for cities and both have large impacts on human health and economic development. Although there are many long term opportunities to address these issues with integrated policies, the immediate needs of addressing air pollution and climate change mitigation are not the same for all countries in the short run. We examined the relationships between greenhouse gases (GHG) emissions, outdoor air pollution, and levels of socioeconomic development to identify specific near-term mitigation policy responses to climate change and air pollution for countries with different levels of human development. Human development index, as defined by The United Nations Development Programme (UNDP) is a measure of achievement in the basic dimensions of human development across countries, which combines the gross national income index, an education index and a life expectancy index (http://hdr.undp.org/en/humandev). Country-level data were collected on indicators of socioeconomic development, emissions of GHG, and outdoor levels of fine particulate matter (PM2.5) from the World Bank, the UNDP, and the Task Force on Hemispheric Transport of Air Pollution. Differences in GHG emissions and air pollution concentrations, as well as socioeconomic development indicators, were assessed at national, sub-national, and global scales. Countries were divided into four categories based on CO2 emissions per capita and an estimation of outdoor PM2.5: Group A was characterized by high CO2 emissions per capita and low PM2.5 concentrations, Group B by high CO2 emissions per capita and high PM2.5 concentrations, Group C by low CO2 emissions per capita and low PM2.5 concentrations, and Group D by low CO2 emissions per capita and high PM2.5 concentration. Per-capita emissions of CO2 were strongly correlated with the level of socioeconomic development, while differences in non-CO2 greenhouse gas emissions per capita across the groups were not correlated. Atmospheric PM2.5 concentrations were not correlated with either CO2 emissions per capita or levels of socioeconomic development. Energy and environmental policies focused on CO2 emission reductions may not inherently lead to development pathways that sufficiently reduce population exposure to air pollution. Countries with low CO2 and high air pollution levels should pursue short-term policies to reduce air pollution and increase human development, beginning to address GHG emissions after critical human health and development needs are met.

Outdoor fungal spores and acute respiratory effects in vulnerable individuals

BackgroundMany outdoor fungal spores are ubiquitous, respirable and possibly allergenic. They may contribute to asthma symptoms; however, little is known about their effects on respiratory function. ObjectiveTo investigate if outdoor fungal spore levels were associated with lung function or airway inflammation, and whether fungal sensitization or current asthma modified any associations. MethodsCross-sectional associations between same day (Lag0) and cumulative 3-day lagged (Lag0-3) counts of 12 outdoor fungal spore taxa and pre-bronchodilator spirometry (FEV1, FVC, FEF25%–75%), bronchodilator response (BDR) and airway inflammation (fractional exhaled nitric oxide (FeNO) and exhaled breath condensate (EBC) nitrogen oxides (NOx) and pH were investigated in 936 Melbourne Atopy Cohort Study participants during September 2009 to December 2011. Generalized linear models were used to quantify associations with lung function, FeNO and EBC pH; generalized estimating equations for BDR; and ordinal logistic regression for EBC NOx. Models were adjusted for age, sex, height, temperature, relative humidity, grass pollen and sample storage time. Potential effect modification by fungal sensitization and current asthma were examined using interaction terms. ResultsMixed associations were found. Higher levels of Ustilago/smuts were associated with lower lung function at Lag0 (FEV1: 21ml [95%CI -36, −7]; FEF25%–75%: 39ml [-65, −13]) and Lag0-3 (FEV1: 9ml [-14, −4]; FEF25%–75% −18ml [-27, −9]). Positive BDR was associated with Ustilago/smuts (Lag0 OR = 1.1 [1.04, 1.2]; Lag0-3 OR = 1.04 [1.02, 1.07]), Alternaria (Lag0 OR = 1.3 [1.0, 1.6]) and Drechslera (Lag0 OR = 1.1 [1.03, 1.2]). Higher EBC NOx was associated with Cladosporium (Lag0-3 OR = 1.1 [1.0, 1.2]), Alternaria (Lag0-3 OR = 1.1 [1.0, 1.3]). No associations were found with higher FeNO. In those with fungal sensitization, Ustilago/smuts and Drechslera were associated with lower FEV1 and FVC; Cladosporium was associated with increased FEV1, FVC and FEF25%–75% but also with higher FeNO and lower EBC pH. In those with current asthma, Alternaria, Ustilago/smuts and Drechslera were associated with lower FEV1, FVC, FEF25–75% and EBC pH. ConclusionExposure to outdoor fungal spores may be associated with lower lung function and increased airway inflammation, particularly in those with fungal sensitization and/or current asthma.

Indoor and Outdoor Exposure to Radon, Thoron and Thoron Decay Products in a NORM Area with Highly Elevated Bedrock Thorium and Legacy Mines.

Radon (222Rn) and thoron (220Rn), and especially their short-lived decay products, are major contributors to dose received by the public from naturally occurring radioactive material (NORM), particularly in areas with elevated levels of naturally occurring radionuclides. Mining in such areas can involve ventilation of high amounts of these gases, which may influence outdoor levels. In this work, we assessed indoor and outdoor levels of 222Rn, 220Rn and 220Rn decay products (TnDP) in close proximity to an area with elevated bedrock levels of thorium (232Th) and a NORM legacy mining site with high natural ventilation. We assess municipal buildings at distances from a few hundred meters to 2 km from the NORM legacy mines. In some buildings, high indoor levels of 222Rn were observed in winter, as expected for temperate areas. In summer, high indoor levels of 222Rn and 220Rn were observed in some buildings, and very low associated levels of TnDP in actively ventilated buildings may suggest entry by ventilation and an outdoor source. Outdoor levels of TnDP increased with decreased distance from the legacy mines, suggesting dispersal from these during both summer and winter.

Interdependency of Soil-gas Radon-222 Concentration on Soil Porosity at different Soil-depths

Origination of Radon-222 (222Rn) from soil and its concentration, contributing to the highest exposure of ionizing radiation to the public is natural. It is a known radioactive gas and its percentage in concentrations contributing to outdoor radon atmospheric level depends on some physical parameters of the soil. To ascertain some of its dependency on soil porosity, a radiometric survey was carried out on soil depths at varying locations and the laboratory analysis was carried out on the soil sample at each location and depth in order to determine its porosity. The measurements were done using radon detector at five (5) locations. At each location, data were collected at four (4) different soil depths of 20, 40, 60 and 100 cm respectively. In addition, soil samples at these locations and depths were taken to the laboratory for porosity test. The result showed that highest value of 222Rn concentration at 100 cm depth is 24680 ± 1960 Bqm−3 with maximum porosity level of 69.92%, while the lowest concentration at 100 cm depth is 7370 ± 1139 Bqm−3 with minimum porosity level 51.61% respectively. Inferentially, a statistical analysis carried out using Pearson correlation showed that there exist some relationships between soil-gas 222Rn concentrations measured and soil porosity determined at each measurement soil-depths. The nature of the established relationship shows interdependency of 222Rn on soil porosity at different depths, such that if the soil porosity is known, its corresponding soil-gas radon concentration can be determined.

The relationship between indoor and outdoor levels of PM10 and its chemical composition at schools in a coastal region in Spain

PM10 levels and its chemical composition were studied inside and outdoor of seven primary schools (3 in urban environment, 3 in industrial environment, 1 in rural environment) located in the Mediterranean coast in an area with an important industrial nucleus dedicated to the treatment of raw mineral materials. The main objective of this work is a comparison between these levels obtained inside and outside schools and also asses the influence of various natural and anthropogenic emission sources on particles concentrations found inside. The indoor airborne samples were collected using RespiCon TM. In the three outdoor sampling stations was used a minivol air sampler type 3.1 LVS of Derenda. PM10 Chemical composition was obtained by ICP-MS (elements) and ion chromatography The ratio I/O (indoor/outdoor) has been calculated taking into account only the samples taken in the same conditions. In all schools the ratio I/O for PM10 was greater than unity (between 1.3 and 7.8), indicating that existed significant indoor sources of these particles. In the three schools located in the industrial environment were collected PM10 samples inside and outside in non-teaching periods. Comparing the values of I/O when the classrooms were unoccupied with respect to the average value of these same schools when the classrooms are occupied, the behaviour is different depending on the location. On the other hand, a sample in an industrial school was obtained when some infrastructure works were being carried out outside of school. This caused a significant increase in the concentration of particles in the interior (I/O = 19.9). From the levels of As, Ni, Cd, Pb, Al, B, Zn, Mg, Sb, F−, ClO2-, NO3- and SO42- in PM10 inside and outside of each school, also the ratios I/O were calculated. These chemical ratios I/O were higher than unity in all cases and generally higher than those recorded in the case of PM10. Finally, Pearson correlation coefficients (r) between the elements and anions and the PM10, and between the different elements and anions were calculated for the purpose of establishing the existence of common emission sources.

Indoor measurements of air pollutants in residential houses in urban and suburban areas: Indoor versus ambient concentrations.

Indoor exposure to air pollutants was assessed through 99 visits to 51 homes located in downtown high-rise buildings and detached houses in suburban and rural areas. The ambient concentrations of ultrafine particles (UFP), black carbon (BC), particulate matter smaller than 2.5 μm in diameter (PM2.5), and trace elements were concurrently measured at a central monitoring site in downtown Toronto. Median hourly indoor concentrations for all measurements were 4700 particles/cm3 for UFP, 270 ng/m3 for BC, and 4 μg/m3 for PM2.5, which were lower than ambient outdoor levels by a factor of 2-3. Much higher variability was observed for indoor UFP and BC across the homes compared to ambient levels, mostly due to the influence of indoor cooking emissions. Traffic emissions appeared to have a strong influence on the indoor background (i.e., outdoor-originated) concentrations of BC, UFP, and some trace elements. Specifically, 85% and 34% of the indoor concentrations of BC and UFP were predominantly from outdoor sources, respectively. Moreover, a positive correlation was observed between indoor concentrations of BC and UFP and total road length within a 300 m buffer zone. There was no significant decrease in indoor air pollution with increasing floor level among high-rise residences. In addition to the influence of outdoor sources on indoor air quality, indoor sources contributed to elevated concentrations of K, Ca, Cr, and Cu. A factor analysis was performed on trace elements, UFP, and BC in homes to further resolve possible sources. Local traffic emissions, soil dust, biomass burning, and regional coal combustion were identified as outdoor-originated sources, while cooking emissions was a dominant indoor source. This study highlights how outdoor sources can contribute to chronic exposure in indoor environments and how indoor activities can be associated with acute exposure to temporally varying indoor-originated air pollutants.

Development of a low-cost air sensor package and indoor air quality monitoring in a California middle school: Detection of a distant wildfire

ABSTRACTA low-cost air sensor package was used to monitor indoor air quality (IAQ) in a classroom at the Albany Middle School in the San Francisco Bay Area of California. A rapid increase in carbon dioxide (CO2) was observed in the classroom as soon as it is occupied. When the classroom is unoccupied, the CO2 levels decay slowly toward the outdoor background level. All high CO2 concentrations observed inside the classroom, above the outdoor background, was due to exhaling of the occupants. The CO2 concentrations generally exceed the recommended level of 1000 ppb towards the end of the school day. The exceedances and slow decay may suggest that the ventilation rate in this school is not sufficient. The particulate level in the classroom was low until a distant wildfire advected large amount of particulate matter to the San Francisco Bay Area. Very high (10–15 times compared to the background) particle numbers (per m3 of particles with diameter >0.3 µm) were observed in the classroom during the wildfire. These particles were relatively small (0.3–1.0 µm) and the filters (MERV 8) of the ventilation system were unable to filter them out. Therefore, the measurements made by low-cost particle counters can inform the school administrators of adverse IAQ during future wildfire (or other combustion) events. The particle number was independent of the occupation before and during the wildfire suggesting that all observed particles were infiltrated into the classroom from outside. Consistent with previous studies, no appreciable increase in the local ambient CO2 background was observed during this distant wildfire event.Implications: Low-cost air sensors are effective in monitoring indoor air quality in classrooms. The CO2 levels in classrooms are mainly generated indoors due to exhalation of occupants. Concentration of CO2 generally exceed the recommended level of 1000 ppb towards the end of the school day. In contrast, the particulate matter mostly comes from outdoors and small particles penetrate though the filters normally used at schools. Distant wildfires do not increase the local CO2 background appreciably, but significantly increase the particulate matter concentrations both indoors and outdoors. Further investigations are needed to assure that ventilation rates in classrooms are sufficiently health protective.

Indoor and Outdoor Exposure to Volatile Organic Compounds and Health Risk Assessment in Residents Living near an Optoelectronics Industrial Park

This study aimed to determine indoor and outdoor levels of volatile organic compounds (VOCs) and to assess potential risks among residents living in the vicinity of an optoelectronics industrial park in 2006–2007. We used steel canisters to collect 72 indoor samples and 80 outdoor samples over 24 h. Gas chromatography with a mass-selective detector was used for qualitative and quantitative analyses. The amounts of time residents spent doing activities in different microenvironments were determined by the self-administered questionnaire. The chronic hazard index (HIc) and cancer risk were applied to assess the non-carcinogenic and carcinogenic risks of VOCs among residents. Four VOCs of ethanol (indoor: 77.8 ± 92.8 μg/m3; outdoor: 26.8 ± 49.6 μg/m3), toluene (67.0 ± 36.7 μg/m3; 56.9 ± 19.0 μg/m3), m/p-xylene (50.8 ± 66.1 μg/m3; 21.2 ± 20.3 μg/m3), and acetone (37.7 ± 27.5 μg/m3; 25.8 ± 9.8 μg/m3) were identified as dominant components in both the indoor and outdoor environments. Total VOCs and six VOCs of benzene, toluene, ethylbenzene, m/p-xylene, o-xylene, and ethanol in indoor sites were significantly higher than those in outdoor sites (all p-values < 0.05). All estimated HIc values were less than unity and the cancer risk of benzene exposure was 1.8 × 10−4 (range: 9.3 × 10−5 to 3.4 × 10−4) based on resident time-weighted patterns. Strategies to reduce benzene exposure should be implemented to protect public health.

A comprehensive risk assessment of human inhalation exposure to atmospheric halogenated flame retardants and organophosphate esters in an urban zone

Inhalation exposure to flame retardants used as additives to minimize fire risk and plasticizers is ubiquitous in human daily activities, but has not been adequately assessed. To address this research gap, the present study conducted an assessment of human health risk for four age groups through inhalation exposure to size fractionated particle-bound and gaseous halogenated flame retardants (polybrominated diphenyl ethers (PBDEs) and alternative halogenated flame retardants (AHFRs)) and organophosphate esters (OPEs) at indoor and outdoor environments (school, office, and residence) in three districts of a megacity (Guangzhou, China). Results demonstrated that OPEs were the dominant components among all targets. Indoor daily intakes of PBDEs and OPEs were 13–16 times greater than outdoor levels for all age groups. Gaseous OPEs contributed significantly greater than particle-bound compounds to daily intakes of all target compounds. Based on the different life scenarios, hazard quotient (HQ) and incremental life cancer risk (ILCR) from adults exposure to PBDEs and OPEs in indoor and outdoor settings were the greatest, followed by adolescents, children, and seniors. The estimated HQ and ILCR for all age groups both indoors and outdoors were lower than the safe level (HQ = 1 and ILCR = 10−6), indicating that the potential health risk for local residents in Guangzhou via inhalation exposure to atmospheric halogenated flame retardants and OPEs was low.

Shedding Some Light in the Dark-A Comparison of Personal Measurements with Satellite-Based Estimates of Exposure to Light at Night among Children in the Netherlands.

Background:Exposure to light at night (LAN) can perturb the biological clock and affect sleep and health. Previous epidemiological studies have evaluated LAN levels measured by satellites, but the validity of this measure as a proxy for personal LAN exposure is unclear. In addition, outdoor satellite-measured LAN levels are higher in urban environments, which means that this measure could potentially represent a proxy for other, likely urban, environmental exposures.Objectives:We evaluated correlations of satellite-assessed LAN with measured bedroom light levels and explored correlations with other environmental exposures, in particular, air pollution, green space, and area-level socioeconomic position (SEP).Methods:We compared satellite measurements with evening and nighttime bedroom measurements of illuminance (in units of lux) for 256 children, and we evaluated correlations between satellite-based measures and other urban exposures such as air pollution, area-level SEP, and surrounding green space for 3,021 children.Results:Satellite-measured LAN levels (nanowatts per centimeter squared per steradian) were not correlated with measured evening or nighttime lux levels [Spearman correlation coefficients () to 0.04]. There was a weak correlation with measurements during the darkest time period if parents and their children reported that outdoor light sometimes or usually influenced indoor light levels (, ). In contrast, satellite-measured LAN levels were correlated with air pollution ( with , with ), and surrounding green space ( for green space within of the home). A weak correlation with area-level SEP was also observed ().Conclusions:Outdoor satellite-assessed outdoor LAN exposure levels were correlated with urban environmental exposures, but they were not a good proxy for indoor evening or nighttime personal exposure as measured in our study population of 12-y-old children. Studies planning to evaluate potential risks from LAN should consider such modifying factors as curtains and indoor lighting and the use of electronic devices and should include performing indoor or personal measurements to validate any exposure proxies. The moderate-to-strong correlation of outdoor LAN with other environmental exposures should be accounted for in epidemiological investigations. https://doi.org/10.1289/EHP3431

Monitoring and assessment of formaldehyde levels in residential areas from two cities in Romania.

Formaldehyde has become a ubiquitous contaminant in the air, and people are exposed to it worldwide. However, few studies have evaluated the temporal-spatial levels/changes of formaldehyde exposure at residences, and the relationship between its outdoor and indoor levels has been rarely examined. The aim of this study was to assess community formaldehyde exposure in Sebes and Aiud, Romania to identify: (1) home environment characteristics that may play an important role in exposure; and understand: (2) if there were differences in formaldehyde levels between the two cities; (3) if there were temporal variations within each city; and (4) whether outdoor formaldehyde levels influence indoor levels. We simultaneously performed indoor and outdoor active air sampling for formaldehyde at each investigated residential location over a 3-year period and analyzed the samples by gas chromatography with flame ionization detector (GC-FID). The mean values of indoor and outdoor formaldehyde levels in both cities fell in the range 0.014-0.035 mg/m3. The correlation analysis indicated mostly positive but not significant (p > 0.05) correlations between indoor formaldehyde and microclimate factors (temperature, humidity, pressure). Notably, home insulation was found to be significantly correlated with increased indoor formaldehyde levels. There were no significant differences in mean indoor or outdoor formaldehyde levels between Sebes and Aiud over the 3-year study period. When comparing the formaldehyde levels in both cities over the 3-year period, only outdoor formaldehyde levels were significantly higher in 2016, as compared to those in 2017 and 2018.

Characterizing sources and emissions of volatile organic compounds in a northern California residence using space- and time-resolved measurements.

We investigate source characteristics and emission dynamics of volatile organic compounds (VOCs) in a single-family house in California utilizing time- and space-resolved measurements. About 200 VOC signals, corresponding to more than 200 species, were measured during 8weeks in summer and five in winter. Spatially resolved measurements, along with tracer data, reveal that VOCs in the living space were mainly emitted directly into that space, with minor contributions from the crawlspace, attic, or outdoors. Time-resolved measurements in the living space exhibited baseline levels far above outdoor levels for most VOCs; many compounds also displayed patterns of intermittent short-term enhancements (spikes) well above the indoor baseline. Compounds were categorized as "high-baseline" or "spike-dominated" based on indoor-to-outdoor concentration ratio and indoor mean-to-median ratio. Short-term spikes were associated with occupants and their activities, especially cooking. High-baseline compounds indicate continuous indoor emissions from building materials and furnishings. Indoor emission rates for high-baseline species, quantified with 2-hour resolution, exhibited strong temperature dependence and were affected by air-change rates. Decomposition of wooden building materials is suggested as a major source for acetic acid, formic acid, and methanol, which together accounted for ~75% of the total continuous indoor emissions of high-baseline species.

Assessment of indoor and outdoor background radiation levels at school of technology, Kano State Polytechnic, Kano State-Nigeria

A Survey taken by the world health organization (WHO) and the international commission on radiation protection (ICRP) shows that residents of temperate climate spends only about 20% of their time outdoor and about 80% indoors and certain materials use for the construction of such buildings (rocks, soils, tiles etc) are known to be radioactive, and exposure to such radiation results in critical health challenges. Assessment of indoor and outdoor background ionizing radiation level at School of Technology, Kano State Polytechnic, Nigeria was carried out using a digital radiation meter (Radiation Alert Inspector). A total of 49 areas were surveyed and the results obtained showed that the annual indoor reading were highest at Compounding Lab. (2.368±0.35 mSv/yr) and Old Chemistry Lab. (2.169±0.35 mSv/yr), and lowest at New Biology Lab. (1.219±0.21 mSv/yr) and Press Workshop (1.303±0.35 mSv/yr). For the outdoor areas, SOT ring road was found to have the highest value of 0.557±0.17 mSv/yr, while Zoological Garden has the lowest effective value of 0.280±0.05 mSv/yr. For the lecture venues, Auditorium has the highest indoor annual equivalent dose of 2.060±0.49 mSv/yr, while H-Block ND I Textile Class recorded the lowest values of 1.275±0.27 mSv/yr. Base on the aforementioned findings, it was deduced that radiation levels are within the permissible radiation limit as stipulated by the ICRP and UNSCEAR of 2.4 mSv/yr and thus, SOT Kano is radiologically safe.Keywords: Indoor and outdoor, background radiation, equivalent dose, Digital Radiation meter

Are we safe inside? Indoor air quality in relation to outdoor concentration of PM10 and PM2.5 and to characteristics of homes

This study investigates the relationship between concentrations of particulate matter (PM10 and PM2.5) outdoors and indoors, and evaluates the significance of various factors which may influence levels of particle pollution inside homes. Twenty-four hour measurements of the concentrations of PM10 and PM2.5 were carried out in 179 locations in Krakow, simultaneously indoors and outdoors, using personal aerosol monitors. Data about the characteristics of homes where measurements were conducted were collected by a questionnaire. Even though daily average outdoor levels of PM10 and PM2.5 were higher than indoor levels (p < 0.001), a strong, statistically significant correlation was found between outside and inside concentrations of both PM10 (r = 0.78, p < 0.001) and PM2.5 (r = 0.82, p < 0.001). After controlling for outdoor measurements, the strongest predictors of indoor pollution were the types of windows, the heating season, and the heating method. The increase in concentrations of PM10 and PM2.5 outside is accompanied by an increase of indoor concentrations, therefore actions to improve urban air quality will result in improved indoor air quality. In addition, modernization of apartments, especially replacing old windows and changing the heating system would also contribute to the improvement of indoor air quality, and thus quality of life.

Flexible real-time ventilation design in a subway station accommodating the various outdoor PM10 air quality from climate change variation

Indoor air quality (IAQ) in subway stations are dynamic due to various time-dependent factors, such as subway schedule, passenger load variance in short time scale, and outdoor air quality variation cause from climate change. To remove the indoor pollutants, a conventional mechanical ventilation system is typically utilized in subway stations; however, the working mechanism does not consider the real-time variation of the factors that may cause energy waste or deficiency. Therefore, for a quick response in controlling the time-varying indoor PM10 concentration and to design a well-adapted control system for various outdoor air quality (OAQ), a flexible optimal real-time ventilation control strategy was developed. Moreover, the optimal set-points of the PM10 concentration in the platform are determined by the multi-objective genetic algorithm (MOGA) at different time intervals to keep a balance of the energy consumption while maintaining healthy levels of IAQ. Experimentally, three cases were then specified and analyzed based on various outdoor PM10 health levels (i.e. clean, moderate, and contaminated). The results show that a real-time ventilation system can keep the platform at a healthy IAQ level in all cases. Under clean outdoor air conditions, the controlled system can reduce the energy consumption of the ventilation system by 10.3%. On the other hand, for the contaminated outdoor air condition, the peak value of the platform PM10 concentration was reduced by approximately 14 μg/m3 and the indoor air level in an underground station was changed from unhealthy to a moderate level.

Wood stove use and other determinants of personal and indoor exposures to particulate air pollution and ozone among elderly persons in a Northern Suburb.

A six‐month winter‐spring study was conducted in a suburb of the northern European city of Kuopio, Finland, to identify and quantify factors determining daily personal exposure and home indoor levels of fine particulate matter (PM2.5, diameter <2.5 µm) and its light absorption coefficient (PM2.5abs), a proxy for combustion‐derived black carbon. Moreover, determinants of home indoor ozone (O3) concentration were examined. Local central site outdoor, home indoor, and personal daily levels of pollutants were monitored in this suburb among 37 elderly residents. Outdoor concentrations of the pollutants were significant determinants of their levels in home indoor air and personal exposures. Natural ventilation in the detached and row houses increased personal exposure to PM2.5, but not to PM2.5abs, when compared with mechanical ventilation. Only cooking out of the recorded household activities increased indoor PM2.5. The use of a wood stove room heater or wood‐fired sauna stove was associated with elevated concentrations of personal PM2.5 and PM2.5abs, and indoor PM2.5abs. Candle burning increased daily indoor and personal PM2.5abs, and it was also a determinant of indoor ozone level. In conclusion, relatively short‐lasting wood and candle burning of a few hours increased residents’ daily exposure to potentially hazardous, combustion‐derived carbonaceous particulate matter.

Personal exposure to PM2.5 in Chinese rural households in the Yangtze River Delta.

High levels of PM2.5 exposure and associated health risks are of great concern in rural China. For this study, we used portable PM2.5 monitors for monitoring concentrations online, recorded personal time-activity patterns, and analyzed the contribution from different microenvironments in rural areas of the Yangtze River Delta, China. The daily exposure levels of rural participants were 66μg/m3 (SD 40) in winter and 65μg/m3 (SD 16) in summer. Indoor exposure levels were usually higher than outdoor levels. The exposure levels during cooking in rural kitchens were 140μg/m3 (SD 116) in winter and 121μg/m3 (SD 70) in summer, the highest in all microenvironments. Winter and summer values were 252μg/m3 (SD 103) and 204μg/m3 (SD 105), respectively, for rural people using biomass for fuel, much higher than those for rural people using LPG and electricity. By combining PM2.5 concentrations and time spent in different microenvironments, we found that 92% (winter) and 85% (summer) of personal exposure to PM2.5 in rural areas was attributable to indoor microenvironments, of which kitchens accounted for 24% and 27%, respectively. Consequently, more effective policies and measures are needed to replace biomass fuel with LPG or electricity, which would benefit the health of the rural population in China.

Ambient air pollution and overweight and obesity in school-aged children in Barcelona, Spain

BackgroundAmbient air pollution may increase the risk of overweight and obesity in children. However, available evidence is still scarce and has mainly focused on ambient air pollution exposure occurring at home without considering the school environment. The aim of this study is to assess whether exposure to ambient air pollution at home and school is associated with overweight and obesity in primary school children. MethodsWe studied 2660 children aged 7–10 years during 2012 in Barcelona. Child weight and height were measured and age- and sex-specific z-scores for body mass index (zBMI) were calculated using the WHO growth reference 2007. Overweight and obesity were defined using the same reference. Land use regression models were used to estimate levels of nitrogen dioxide (NO2), particulate matter <2.5 μm (PM2.5), <10 μm (PM10) and coarse (PMcoarse) at home. Outdoor levels of NO2, PM2.5, elemental carbon (EC), and ultrafine particles (UFP) were measured in the schoolyard. Multilevel mixed linear and ordered logistic models were used to assess the association between ambient air pollution (continuous per interquartile range (IQR) increase and categorical with tertile cutoffs) and zBMI (continuous and ordinal: normal, overweight, obese), after adjusting for socio-demographic characteristics. ResultsAn IQR increase in PM10-home (5.6 μg/m3) was associated with a 10% increase in the odds of being overweight or obese (odds ratio (OR) = 1.10; 95% CI = 1.00, 1.22). Children exposed to the highest tertile of UFP-school (>27,346 particles/cm3) had a 30% higher odds of being overweight or obese (OR = 1.30; 95%CI = 1.03, 1.64) compared to the lowest tertile of UFP exposure. We also observed that exposure to NO2, PM2.5 or EC at schools was associated with higher odds of overweight or obese at medium compared to low levels of exposure. Home and school exposures did not show any significant associations with zBMI (except PM2.5-school comparing tertile 2 vs tertile 1) but were similar in direction. ConclusionsThis study suggests that exposure to ambient air pollution, especially at school, is associated with childhood risk for overweight and obesity. A cautious interpretation is warranted because associations were not always linear and because school and home air pollution measurements were not directly comparable.