Outdoor Levels Research Articles

Uncertainty analysis of various CO2-Based tracer-gas methods for estimating seasonal ventilation rates in classrooms with different mechanical systems

Indoor air quality (IAQ) data of 220 classrooms in the Midwestern region of the US were measured during 2015–2017. During three seasons (fall, winter, and spring), indoor and outdoor CO2 concentrations of each classroom were measured under both occupied and unoccupied conditions. To calculate ventilation rates from the collected CO2 data, three main methods derived from the mass-balance equation were used: (1) steady-state; (2) decay rate; and (3) build-up. Since the uncertainty of the individual measurement parameter affects the accuracy or reliability of the calculated, an uncertainty analysis was performed for all three methods. The uncertainty of the estimated ventilation rates in relation to the volume of the classroom, indoor and outdoor CO2 levels, and estimated student CO2 emission rates were determined. The study shows that the steady-state method has the least uncertainty in ventilation rate calculations, while the decay and build-up methods had the lowest and highest values for ventilation rates, respectively. The results also show the estimated ventilation has a larger variance in single-zone systems than in multiple-zone systems. In field measurements, CO2 readings contribute to the largest portion of uncertainty for all three methods. Therefore, with CO2 as the tracer gas, improving the accuracy of CO2 measurement should receive the highest priority for study.

Summertime physiological and thermal responses among activity levels in campus outdoor spaces in a humid subtropical city

We identified physiological and thermal responses to different activity levels on a campus during summertime in Xi'an, a humid subtropical city in China. Physiological responses and thermal comfort of 54 healthy college students while undertaking different physical activities (light, moderate and vigorous intensities) in six campus open spaces were investigated using meteorological measures, longitudinal questionnaire surveys and physiological parameters. Physiological Equivalent Temperature (PET) and Universal Thermal Climate Index (UTCI) were chosen as the thermal indices, while blood pressure (BP), heart rate (HR) and skin temperature (ST) were selected as physiological evaluation measures. Results demonstrated that: 1) Types and proportions of thermal symptoms were positively related to outdoor spatial characteristics and physical activity levels. The proportion of thermal discomfort increased 33, 50 and 83% as activity intensities increased from light through moderate to vigorous. 2) BP and HR reflected human activity levels. HR clearly represented metabolic trends. 3) ST accurately represented physiological responses among spaces across activity levels. However, mean skin temperature (MST) was poorly related to thermal sensation vote (TSV). 4) As activity intensity ranged from light through moderate to vigorous, neutral UTCI declined by 27.6 °C, 25.6 °C, 22.0 °C, and neutral PET declined by 26.1 °C, 22.1 °C, 11.9 °C. 5) Outdoor spaces shaded by trees or pavilions were more comfortable for outdoor activities than these with low or middle SVF during summer.

Dust Events and Indoor Air Quality in Residential Homes in Kuwait.

Kuwait is a developed Middle Eastern country that is impacted by frequent dust storms from regional and/or remote deserts. The effectiveness of keeping homes tightly closed during these events to reduce dust exposures was assessed using indoor and outdoor particle samples at 10 residences within the metropolitan Kuwait City area. Specifically, this study compared indoor and outdoor levels of black carbon and 19 trace elements (Na, Mg, Al, Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Br, Sr, and Zr) during dust and non-dust events and found that particle penetration efficiencies were lower during dust storm events (less than 20–30%) than during non-dust storm events (40–60%). Coarse particles had lower penetration efficiency compared to fine particles, which is due to differences in infiltration rates and settling velocities between these two size fractions. Our findings suggest that increasing home insulation could be an effective strategy to reduce indoor exposure to crustal particles from dust storm events in residential houses of Kuwait City.

Association Between Cardiovascular Disease and Long-term Exposure to Air Pollution With the Risk of Dementia

Emerging yet contrasting evidence associates air pollution with incident dementia, and the potential role of cardiovascular disease (CVD) in this association is unclear. To investigate the association between long-term exposure to air pollution and dementia and to assess the role of CVD in that association. Data for this cohort study were extracted from the ongoing Swedish National Study on Aging and Care in Kungsholmen (SNAC-K), a longitudinal population-based study with baseline assessments from March 21, 2001, through August 30, 2004. Of the 5111 randomly selected residents in the Kungsholmen district of Stockholm 60 years or older and living at home or in institutions, 521 were not eligible (eg, due to death before the start of the study or no contact information). Among the remaining 4590 individuals, 3363 (73.3%) were assessed. For the current analysis, 2927 participants who did not have dementia at baseline were examined, with follow-up to 2013 (mean [SD] follow-up time, 6.01 [2.56] years). Follow-up was completed February 18, 2013, and data were analyzed from June 26, 2018, through June 20, 2019. Two major air pollutants (particulate matter ≤2.5 μm [PM2.5] and nitrogen oxide [NOx]) were assessed yearly from 1990, using dispersion models for outdoor levels at residential addresses. The hazard of dementia was estimated using Cox proportional hazards regression models. The potential of CVD (ie, atrial fibrillation, ischemic heart disease, heart failure, and stroke) to modify and mediate the association between long-term exposure to air pollution and dementia was tested using stratified analyses and generalized structural equation modeling. At baseline, the mean (SD) age of the 2927 participants was 74.1 (10.7) years, and 1845 (63.0%) were female. Three hundred sixty-four participants with incident dementia were identified. The hazard of dementia increased by as much as 50% per interquartile range difference in mean pollutant levels during the previous 5 years at the residential address (hazard ratio [HR] for difference of 0.88 μg/m3 PM2.5, 1.54 [95% CI, 1.33-1.78]; HR for difference of 8.35 μg/m3 NOx, 1.14 [95% CI, 1.01-1.29]). Heart failure (HR for PM2.5, 1.93 [95% CI, 1.54-2.43]; HR for NOx, 1.43 [95% CI, 1.17-1.75]) and ischemic heart disease (HR for PM2.5, 1.67 [95% CI, 1.32-2.12]; HR for NOx, 1.36 [95% CI, 1.07-1.71]) enhanced the dementia risk, whereas stroke appeared to be the most important intermediate condition, explaining 49.4% of air pollution-related dementia cases. This study found that long-term exposure to air pollution was associated with a higher risk of dementia. Heart failure and ischemic heart disease appeared to enhance the association between air pollution and dementia, whereas stroke seemed to be an important intermediate condition between the association of air pollution exposure with dementia.

Spatial estimation of outdoor NO2 levels in Central London using deep neural networks and a wavelet decomposition technique

Outdoor air pollution remains a major environmental threat to the public, especially those who reside in highly urbanised areas. Recent studies have revealed the effectiveness of early-warning mechanisms that enable the public reduce their exposure to air pollutants. This highlights the need for accurate air quality forecasts. However, air quality in many developing and highly urbanised countries remains unmonitored. Hence, a novel spatiotemporal interpolation modelling approach based on a deep learning and wavelet pre-processing technique was proposed in this paper. In more detail, Long Short-term Memory (LSTM) neural networks and Discrete Wavelet Transformation (DWT) were utilised to model the spatial variability of hourly NO2 levels at six urban sites in Central London, the United Kingdom. The models were trained using only the NO2 concentration data from the neighbouring sites. Benchmark models such as plain LSTM and Multilayer Perceptron (MLP) models were also developed to validate the effectiveness of the proposed models. The proposed wavelet-based spatiotemporal models were found to provide superior forecasting results, explaining 77% to 93% of the variability of the actual NO2 concentration levels at most sites. The overall results reveal the very promising potential of the proposed models for the spatiotemporal characterisation of outdoor air pollution.

Exposure Assessment of Indoor PM Levels During Extreme Dust Episodes.

Millions of people live in areas that are subject to frequent dust events; however gaps remain in our knowledge about the association between dust, air quality and corresponding particulate matter (PM) exposure levels inside buildings. This case study demonstrates how the PM2.5 and PM10 levels in an urban environment respond to strong natural dust episodes. Real-time measurements were recorded simultaneously in indoor and outdoor environments in households in the city of Beer-Sheva, Israel during several strong dust events. A typical strong event was used for a detailed analysis of PM10 and PM2.5. Outdoor daily concentrations were above 1000 µg m−3 for PM10, the maximum hourly value of which was 1320 µg m−3. The indoor PM10 peaked at about 700 µg m−3 and fluctuated in parallel with the outdoor level but with a time lag of about 15 min. Indoor air tended to remain for several hours after the dust event had subsided. Analyses of multiple events revealed that the dependence of indoor PM2.5 and PM10 on natural dust varies but is not directly linked to the level of atmospheric dust concentration. From a health perspective, the exposure risk posed by extreme indoor PM2.5 and PM10 levels generated by natural dust episodes should be considered.

Does energy efficiency-indoor air quality dilemma have an impact on the gross domestic product?

Increased energy efficiency of the building stock is one of the main tools to reduce climate change. Improved airtightness of the building envelope has a side effect – the need for higher ventilation rates which, in turn, lead to a higher energy bill and reduced indoor air quality. This creates an energy efficiency – indoor air quality dilemma. This study evaluates the dilemma impact on the gross domestic product (GDP). System dynamics modelling is applied to answer this question. The education system and labour market of Latvia is used as the case study. Simulation results show that even if all education buildings in Latvia have improved energy efficiency performance and have a significant reduction of outdoor CO2 level, indoor CO2 is very high if no mechanical ventilation is used. The best solution is to increase energy efficiency while providing good indoor air quality by operating mechanical ventilation since the increase in GDP provides financial sources for further energy efficiency measures.

The association between indoor and outdoor NO2 levels: A case study in 50 residences in an urban neighbourhood in New Zealand

BackgroundIn the context of inner-city housing intensification, exploring the association between outdoor and indoor air quality is important to quantify any potential health risks. MethodsWe undertook a cross-sectional case study on 50 residences in an inner-city neighbourhood scheduled for urban development, bisected by a busy road. We measured indoor and outdoor NO2, indoor temperature, and undertook a survey on demographic factors and household NO2 sources. We performed a linear regression to examine the association between indoor and outdoor NO2 (measured at the building facade) adjusting for potential confounders. ResultsMean indoor and outdoor levels of NO2 were 8.4 and 12.5 μg/m3 respectively. The unadjusted model showed no significant association between indoor and outdoor NO2. In the fully-adjusted model, a 1 % increase in outdoor NO2 was associated with a 5 % increase in indoor NO2 (95 %CI: 1.2–8.8%). ConclusionA weak association between indoor and outdoor NO2 was found. More intensive housing development in a transport corridor may be possible; however given the health risks of induced by air pollutants starts even at levels below WHO recommended levels, urban policy measures to reduce indoor and ambient air pollution are required.

Background Ionization Radiation in Radiography Centers in Ahvaz, Iran

Background: Exposure to ionizing radiation has harmful health effects. Research shows that people spend more their time indoors than outdoors. Therefore, the indoor background ionizing radiation can pose a noticeable health risk. Objectives: Since it is well established that ionizing radiation can lead to serious health problems, the present study aimed to evaluate the level of ionizing radiation in the background environment in radiological centers in Ahvaz, Iran. Methods: The evaluation of indoor and outdoor background ionizing radiation levels was carried out by using the calibrated digital Geiger-Muller counter (S.E. International Inc., USA) in five radiography centers. The background radiation was measured both indoor and outdoor of the selected radiology centers in four locations. The measured locations included behind the door of the X-ray room, outdoor, waiting room for the people, and the reception section in each center. The measurements were done with a device held one meter above the floor. Results: The indoor radiation levels were 0.13 ± 0.004, 0.11 ± 0.004, 0.13 ± 0.004, 0.16 ± 0.007, and 0.16 ± 0.006 µSv/h for centers a, b, c, d, and e, respectively, and the outdoor radiation levels were 0.12 ± 0.02, 0.11 ± 0.01, 0.10 ± 0.00, 0.12 ± 0.01, and 0.13 ± 0.00 µSv/h, respectively. Conclusions: The mean equivalent dose in this study was lower than the standard level (1 mSv/y); therefore, the radiology centers were safe.

Novel Approaches to Air Pollution Exposure and Clinical Outcomes Assessment in Environmental Health Studies

An accurate assessment of pollutants’ exposure and precise evaluation of the clinical outcomes pose two major challenges to the contemporary environmental health research. The common methods for exposure assessment are based on residential addresses and are prone to many biases. Pollution levels are defined based on monitoring stations that are sparsely distributed and frequently distanced far from residential addresses. In addition, the degree of an association between outdoor and indoor air pollution levels is not fully elucidated, making the exposure assessment all the more inaccurate. Clinical outcomes’ assessment, on the other hand, mostly relies on the access to medical records from hospital admissions and outpatients’ visits in clinics. This method differentiates by health care seeking behavior and is therefore, problematic in evaluation of an onset, duration, and severity of an outcome. In the current paper, we review a number of novel solutions aimed to mitigate the aforementioned biases. First, a hybrid satellite-based modeling approach provides daily continuous spatiotemporal estimations with improved spatial resolution of 1 × 1 km2 and 200 × 200 m2 grid, and thus allows a more accurate exposure assessment. Utilizing low-cost air pollution sensors allowing a direct measurement of indoor air pollution levels can further validate these models. Furthermore, the real temporal-spatial activity can be assessed by GPS tracking devices within the individuals’ smartphones. A widespread use of smart devices can help with obtaining objective measurements of some of the clinical outcomes such as vital signs and glucose levels. Finally, human biomonitoring can be efficiently done at a population level, providing accurate estimates of in-vivo absorbed pollutants and allowing for the evaluation of body responses, by biomarkers examination. We suggest that the adoption of these novel methods will change the research paradigm heavily relying on ecological methodology and support development of the new clinical practices preventing adverse environmental effects on human health.

Concentration and Size Distribution of Bacterial and Fungal Bioaerosols and the Related Exposure Dose

In this study, concentration and size distribution of bioaerosols (bacteria and fungi) were obtained in indoor at minimum ventilation and during the operation of air condition system (ACS). Indoo/Outdoor concentration ratio (I/O) of bacteria and fungi were also determined. In addition, the indoor exposure dose (IED) of bacteria and fungi were calculated. A six-stage Andersen cascade impactor was used for sampling the microorganisms during summer season at Minia University, El-Minia (Egypt). Mean bacterial and fungal concentrations were higher (727±160 and 252±60 CFU/m3, respectively ) at minimum ventilation than the concentrations during ACS (506±120 and 176±44 CFU/m3, respectively ). Indoor bacterial concentration level is three times higher than the fungal level. On the other hand, outdoor bacterial concentration (220±55 CFU/m3) is lower than the outdoor fungal level (300±77 CFU/m3). I/O concentration ratio of bacteria was greater than unity indicating that the main source of bacteria is the human occupancy while the corresponding I/O concentration ratio of fungi was less than unity indicating that the fungi are released from outdoor sources. Mean IED of bacteria (38.5 CFU/kg) was about three times higher than the IED of fungi (13.4 CFU/kg) .

Associations between air pollution and pediatric eczema, rhinoconjunctivitis and asthma: A meta-analysis of European birth cohorts

BackgroundUncertainly continues to exist regarding the role of air pollution on pediatric asthma and allergic conditions, especially as air pollution levels have started to decrease in recent decades. ObjectiveWe examined associations of long-term air pollution levels at the home address with pediatric eczema, rhinoconjunctivitis and asthma prevalences in five birth cohorts (BIB, EDEN, GASPII, RHEA and INMA) from seven areas in five European countries. MethodsCurrent eczema, rhinoconjunctivitis and asthma were assessed in children aged four (N = 6527) and eight years (N = 2489). A multi-morbidity outcome (≥2 conditions versus none) was also defined. Individual outdoor levels of nitrogen dioxide (NO2), nitrogen oxides, mass of particulate matter with an aerodynamic diameter <10 μm (PM10), 10–2.5 μm (PMcoarse) and <2.5 μm (PM2.5), and PM2.5 absorbance were assigned to the birth, four- and eight-year home addresses using highly defined spatial air pollution exposure models. Cohort-specific cross-sectional associations were assessed using logistic regression models adjusted for demographic and environmental covariates and combined in a random effects meta-analysis. ResultsThe overall prevalence of pediatric eczema, rhinoconjunctivitis and asthma at four years was 15.4%, 5.9% and 12.4%. We found no increase in the prevalence of these outcomes at four or eight years with increasing air pollution exposure. For example, the meta-analysis adjusted odds ratios (95% confidence intervals) for eczema, rhinoconjunctivitis and asthma at four years were 0.94 (0.81, 1.09), 0.90 (0.75, 1.09), and 0.91 (0.74, 1.11), respectively, per 10 μg/m3 increase in NO2 at the birth address, and 1.00 (0.81, 1.23), 0.70 (0.49, 1.00) and 0.88 (0.54, 1.45), respectively, per 5 μg/m3 increase in PM2.5 at the birth address. DiscussionIn this large meta-analysis of five birth cohorts, we found no indication of adverse effects of long-term air pollution exposure on the prevalence of current pediatric eczema, rhinoconjunctivitis or asthma.

Ambient air pollution and daily hospital admissions for respiratory system–related diseases in a heavy polluted city in Northeast China

Respiratory disease admission has been increasing in the recent 5years due to heavy air pollutions and bad weather conditions in China. We investigated the short-term association of ambient air pollution with daily counts of hospital admissions due to respiratory infection diseases with stratified analysis by age (0-18, 19-65, and > 65years old), gender (male, female), season (spring, summer, autumn, winter), and disease type (lung infections, asthma, COPD (chronic obstructive disease), URI (upper respiratory infections)) in heavy polluted city of Shenyang in China. Daily ambient air pollution concentrations, weather conditions, and hospital admission counts for 53months (from November 1, 2013 to March 25, 2018) were extracted from related authorities in electronic databases. Associations between outdoor air pollution levels and hospital admissions were estimated for time lags of 0-7days using quasi-Poisson additive regression models, adjusted for meteorological variables, holidays, day of week, and season, as well as eliminating autocorrelations. Single pollutant analysis results showed lung infection diseases were related to all pollutant concentration change with no lag effects. After adjusting for other pollutants and confounding factors, we found NO2 was associated with daily admissions of lung infections (ER = 6.75%, 95% CI 1.24, 12.55), asthma (ER = 20.36%, 95% CI 4.26, 38.95; lag day 5, ER = 18.48%, 95% CI 2.83, 36.51), and COPD (ER = 13.27%, 95% CI 0.46, 27.71); CO was associated with lung infections and asthma with lag effects on lag days 1 and 4; and PM2.5 was associated with COPD admissions on lag day 6. Respiratory hospital admissions in female over 65years old and autumn were more associated with increased air pollutant levels. Our study results might add more detail evidences for relationship studies between air pollution exposure and respiratory diseases and contribute to the precise respiratory disease prevention and air pollution control strategies.

Effects of Air Purifiers on Patients with Allergic Rhinitis: a Multicenter, Randomized, Double-Blind, and Placebo-Controlled Study.

PurposeExposure to particulate matter (PM) is a well-known risk factor in the triggering and exacerbation of allergic airway disease. Indoor environments, where people spend most of their time, are of utmost importance. To assess the effects of air purifiers [equipped with high-efficiency particulate air (HEPA) filters] on allergic rhinitis (AR) in adult patients, we performed a multicenter, randomized, double-blind, and placebo-controlled study.Materials and MethodsPatients with house dust mite (HDM)-induced AR were randomly assigned to either active or mockup (placebo) air-purification groups. Two air purifiers (placed in living room and bedroom) were operated for 6 weeks in each home environment. The primary study endpoint was to achieve improvement in AR symptoms and medication scores. Secondary endpoints were to achieve improvement in the quality of life (QoL) and visual analog scale (VAS) scores, as well as in the indoor (bedroom and living room) concentrations of PM2.5 and PM10.ResultsAfter 6 weeks of air purifier use, medication scores improved significantly in the active (vs. placebo) group, although subjective measures (symptoms, VAS, and QoL scores) did not differ. Bedroom PM2.5 concentrations initially exceeded living room or outdoor levels, but declined (by up to 51.8%) following active purifier operation. Concentrations of PM2.5 in living room and PM10 in bedroom and living room were also significantly reduced through active purification.ConclusionThe use of air purifiers with HEPA filters significantly reduced medication requirements for patients with HDM-induced AR and significantly lowered indoor PM2.5 concentrations, regardless of room placement. Active intervention to reduce household air pollutants may help improve allergic airway disease (clinicaltrials.gov NCT03313453).

Out-Door Air Pollution Levels in Vehicular-Traffic Junctions in Nsukka Metropolis, Enugu Metropolis and Awgu Semi-Urban Area in Enugu State, Nigeria

Studies were carried out to investigate the outdoor air pollution levels in vehicular traffic junctions in the major cities of Nsukka, Enugu and semi-urban area of Awgu all in Enugu State, Nigeria using standard analytical procedures. PM2.5 was collected using Envirotech air sampler, APM 550 and analyzed gravimetrically. Other determined air pollutant gases such as SO2, NO2, O3 and CO were analyzed using colorimetric techniques. The mean hourly traffic density in the vehicular traffic junctions in Nsukka metropolis, Enugu metropolis and Awgu were 2015, 2873 and 587 respectively. The mean range of values of PM2.5, NO2, SO2, O3 and CO in vehicular traffic junctions within the investigated environments were 1.67 - 12.16 μg/m3, 3.72 - 23.83 μg/m3, 2.96 - 30.09 μg/m3, 5.45 - 66.54 μg/m3 and 1.18 - 15.17 ppm respectively. The mean levels of the determined air pollutants in the air around vehicular traffic junctions in Nsukka metropolis, Enugu metropolis and Awgu semi-urban area differed significantly. The mean levels of PM2.5, and CO in the air around vehicular traffic junctions in Enugu metropolis and CO in the air around traffic junctions in Nsukka metropolis were above the recommended permissible limits. Traffic density was therefore seen as the single most important factor contributing to the varying air pollution levels observed in the investigated environments.

Urban greenspace and the indoor environment: Pathways to health via indoor particulate matter, noise, and road noise annoyance

Background/AimThe exposome includes urban greenspace, which may affect health via a complex set of pathways, including reducing exposure to particulate matter (PM) and noise. We assessed these pathways using indoor exposure monitoring data from the HEALS study in four European urban areas (Edinburgh, UK; Utrecht, Netherlands; Athens and Thessaloniki, Greece). MethodsWe quantified three metrics of residential greenspace at 50 m and 100 m buffers: Normalised Difference Vegetation Index (NDVI), annual tree cover density, and surrounding green land use. NDVI values were generated for both summer and the season during which the monitoring took place. Indoor PM2.5 and noise levels were measured by Dylos and Netatmo sensors, respectively, and subjective noise annoyance was collected by questionnaire on an 11-point scale. We used random-effects generalised least squares regression models to assess associations between greenspace and indoor PM2.5 and noise, and an ordinal logistic regression to model the relationship between greenspace and road noise annoyance. ResultsWe identified a significant inverse relationship between summer NDVI and indoor PM2.5 (−1.27 μg/m3 per 0.1 unit increase [95% CI -2.38 to −0.15]) using a 100 m residential buffer. Reduced (i.e., <1.0) odds ratios (OR) of road noise annoyance were associated with increasing summer (OR = 0.55 [0.31 to 0.98]) and season-specific (OR = 0.55 [0.32 to 0.94]) NDVI levels, and tree cover density (OR = 0.54 [0.31 to 0.93] per 10 percentage point increase), also at a 100 m buffer. In contrast to these findings, we did not identify any significant associations between greenspace and indoor noise in fully adjusted models. ConclusionsWe identified reduced indoor levels of PM2.5 and noise annoyance, but not overall noise, with increasing outdoor levels of certain greenspace indicators. To corroborate our findings, future research should examine the effect of enhanced temporal resolution of greenspace metrics during different seasons, characterise the configuration and composition of green areas, and explore mechanisms through mediation modelling.

Estimating time-varying exposures to air emissions from animal feeding operations to assess short-term exposure effects in children with asthma

OPS 07: Farm animals, antibiotics, infections and the microbiome, Room 110, Floor 1, August 27, 2019, 10:30 AM - 12:00 PM Background/Aim: Industrial-scale animal feeding operations (AFOs) have adverse impacts on regional air quality. Air emissions include endotoxins and other pro-inflammatory components, and exposure may cause airway inflammation and respiratory effects in susceptible individuals residing nearby. We aimed to develop and validate metrics for estimating time-varying exposure to AFO air pollution in surrounding communities and, secondly, to determine whether exposure is associated with health effects in children with asthma. Methods: We conducted a longitudinal cohort study of N=58 children with asthma in an agricultural region of Washington State with a high density of dairy AFOs. Children were followed for up to 26 months with repeated measures of respiratory health, and urine was collected in a subcohort (N=16) at biweekly intervals over three months and analyzed for leukotriene E4 (LTE4), a biomarker of systemic inflammation. We developed an approach to estimate daily exposure to AFO airborne emissions based on distance to AFOs, AFO size, and daily wind speed and direction and validated the measure against direct measurements of ammonia, a chemical marker of AFO emissions, measured biweekly at 18 sites across the region for 14 months. Short-term relationships between AFO pollutant exposure and outcomes were assessed using regression models accounting for within-subject correlation and several potential confounders. Results: Estimates of daily AFO air pollution correlated moderately well with outdoor ammonia measurements (N=842; r=0.62). Forced expiratory volume in one second (FEV1) as percent of predicted was 2.0% (95% CI: 0.5, 3.5) lower with each interquartile increase in previous day exposure, but no associations with asthma symptoms were observed. There was suggestive evidence that LTE4 concentrations were higher following days of elevated exposure to AFO emissions (p=0.07). Conclusions: A simple metric of time-varying exposure to AFO emissions predicted daily outdoor ammonia levels. Children with asthma may be adversely affected by exposure to AFO contaminants.

Comparing two approaches for outdoor ambient noise level measurements

In ambient community noise measurements, two possible setups involve an elevated microphone or on the ground [ANSI 12.9-2005/Part 2]. This study compares the elevated and ground-based microphone measurement approaches, particularly for low-frequency wind noise contamination. Wind speed measurements were made at heights of 0.15 m and 1.5 m, and one-third octave spectral histories were recorded simultaneously at the ground and at 1.5 m. The acoustical measurements both used Larson Davis 831C sound level meters, but the elevated microphone setup employed a commercial outdoor windscreen, whereas the ground-based setup utilized a larger reticulated foam windscreen. The measurements, each with durations between 1.5 and 4 h, were repeated at several locations. The results show the ground plate setup is preferable for obtaining wideband spectral measurements for two reasons. First, the wind speed is lower near the ground. Second, for the same wind speed, the larger windscreen yields superior wind noise rejection. These observations are quantified and discussed, and connected to expanding the available noise database for a machine-learning model for soundscape prediction. [Work supported by a U.S. Army SBIR.]In ambient community noise measurements, two possible setups involve an elevated microphone or on the ground [ANSI 12.9-2005/Part 2]. This study compares the elevated and ground-based microphone measurement approaches, particularly for low-frequency wind noise contamination. Wind speed measurements were made at heights of 0.15 m and 1.5 m, and one-third octave spectral histories were recorded simultaneously at the ground and at 1.5 m. The acoustical measurements both used Larson Davis 831C sound level meters, but the elevated microphone setup employed a commercial outdoor windscreen, whereas the ground-based setup utilized a larger reticulated foam windscreen. The measurements, each with durations between 1.5 and 4 h, were repeated at several locations. The results show the ground plate setup is preferable for obtaining wideband spectral measurements for two reasons. First, the wind speed is lower near the ground. Second, for the same wind speed, the larger windscreen yields superior wind noise rejection....

Outdoor and indoor levels of black carbon in central Stockholm, Sweden – implications for epidemiological studies

Outdoor and indoor levels of black carbon in central Stockholm, Sweden – implications for epidemiological studies

Cross-sectional Study of Children’s Respiratory Health and Ambient Air Exposure in two communities in Lanzhou

TPS 682: Long-term health effects of air pollutants 2, Exhibition Hall, Ground floor, August 27, 2019, 3:00 PM - 4:30 PM Objective: The objective of this study was to investigate the potential association between air pollutants and respiratory diseases (RDs) as well as risk factors of children’s respiratory symptoms or morbidity. Methods: With informed consent and written responses, the questionnaire survey concerning children’s personal information, household condition, parents’ behavior, as well as parents’ health history, was conducted in Lanzhou by field investigation. Totally, 2000 local subjects distributing in urban (Chengguan) and suburban (Xigu) communities of Lanzhou were enrolled to participate into the survey. Data on risk factors and on respiratory disease were collected on the basis of double entry and validation of questionnaire. To analyze the effects of various risk factors to children’s respiratory disease, a two-stage regression approach was used in analysis; in the first-stage, the researcher obtained regression logits of community-specific prevalence of asthma, bronchitis, hospitalization, persistent cough and persistent phlegm for respiratory diseases, adjusted for covariates representing personal, family and household variables. Results: Some of the covariates showed to be risk factors of school children’s respiratory disease. However, there were community differences. The results showed that there were associations between community-specific adjusted prevalence rates and ambient air pollutant, also the positive association between morbidity prevalence and outdoor levels of PM2.5. Conclusions: It was found that Children’s grade (2nd grade), exclusive breastfeeding, pet (cat) ownership, parent’s smoking behavior, educational level and medical history of bronchitis and average number of cooking days were found to be risk factors of children’s’ respiratory morbidity. Also, it was found out that at Xigu, asthma was more associated with persistent cough while at Chenggang’s allergic/allergic rhinitis appeared to be more strongly associated.