Anna Leavey

Gestational Age at Birth and Risk of Autism Spectrum Disorders in Alberta, Canada

OBJECTIVE To examine the association between autism spectrum disorders (ASD) and each completed week of gestation using a graphical method of presenting results at all possible categorizations of gestational age (GA). STUDY DESIGN The risk of ASD in a total of 218110 singleton live births with complete data from Alberta, Canada between 1998 and 2004 was examined through linkage to health insurance records. The relative risk of developing ASD according to the 21 dichotomizations of shorter gestation (GA ≤ 23 weeks vs >23 weeks to ≤ 43 weeks vs >43 weeks, in 1-week increments) was calculated using log-binomial regression and adjusted for fetal sex, socioeconomic status, and birth year. RESULTS We observed a gradual increased risk of ASD with shorter gestation. Cutoffs only between 29 and 40 weeks clearly denoted an elevated risk of developing ASD compared with longer gestation, and the risk increased with earlier GA cutoff. The results were not affected by sex or measures of fetal growth. CONCLUSION Our data confirm the role of shortened gestation in ASD risk. We warn against the use of prespecified or a data-driven GA cutoff, however; instead, we recommend systematically examining all plausible cutoffs for GA to avoid overstating the homogeneity of risk in children on either side of a given cutoff, as well as to increase the comparability of studies.

Comparison of Measured Particle Lung-Deposited Surface Area Concentrations by an Aerotrak 9000 Using Size Distribution Measurements for a Range of Combustion Aerosols

Surface area in addition to mass concentration is increasingly being emphasized as an important metric representing potential adverse health effects from exposure to inhaled particles. Lung-deposited surface area (SA) concentrations for a variety of aerosols: coal, biomass, cigarette, incense, candle, and TiO2 were measured using an AeroTrak 9000 (TSI Incorporated) and compared with those calculated from number size distributions from a scanning mobility particle sizer (SMPS). Three methodologies to compute the SA concentrations using the International Commission on Radiological Protections (ICRP) Lung Deposition model and an SMPS were compared. The first method calculated the SA from SMPS size distributions, while the second method used lognormal size distribution functions. A third method generated a closed-form equation using the method of moments. All calculated SMPS SA data against which the measured SA data were compared were generated using the first method only; however, the SA concentrations calculated from each of the three methods demonstrated strong correlations with each other. Overall, results between measured and calculated lung-deposited SA indicated strong positive linear associations (R 2 0.78 - >0.99), moderately dependent on the type of aerosol. In all cases, the measured SA concentrations slightly underestimated those calculated from the SMPS data, with the exception of coal combustion particles. Although some dependency on aerosol material exists, the instrument measuring lung-deposited SA demonstrated consistent reliability across a range of concentrations for a range of materials. For optimal results however, applying a correction factor (CF) before taking the instrument to the field is recommended. Copyright 2013 American Association for Aerosol Research

Real-time particulate and CO concentrations from cookstoves in rural households in Udaipur, India.

Almost 3 billion people around the globe use traditional three-stone cookstoves and open fires to warm and feed themselves. The World Health Organization estimates annual mortality rates from domestic solid fuel combustion to be around 4 million. One of the most affected countries is India. Quantifying pollutant concentrations from these cookstoves during different phases of operation and understanding the factors influencing their variability may help to identify where improvements should be targeted, enhancing indoor air quality for millions of the worlds most vulnerable people. Gas and particulate measurements were collected between June and August, 2012, for 51 households using traditional cookstoves, in the villages of Udaipur district, Rajasthan, India. Mean pollutant concentrations during steady-state mode were 4989 μm(2) cm(-3), 9835 μg m(-3), and 18.5 ppm for lung-deposited surface area, PM2.5, and CO, respectively. Simple and multivariate regression analysis was conducted. Fuel amount, fuel diameter, duration of the cookstove run, roof-type, and the room dimension explained between 7% and 21% of the variability for the pollutant metrics. CO demonstrated weaker correlations with explanatory variables. Some of these variables may be indicative of socio-economic status and could be used as proxies of exposure in lieu of pollutant measurements, hence these variables may help identify which households to prioritize for intervention. Such associations should be further explored.

Organic and inorganic speciation of particulate matter formed during different combustion phases in an improved cookstove

Abstract Residential solid fuel combustion in cookstoves has established health impacts including bladder and lung cancers, cataracts, low birth weight, and pneumonia. The chemical composition of particulate matter (PM) from 4 commonly‐used solid fuels (coal, dung, ambient/dry applewood, and oakwood pellets), emitted from a gasifier cookstove, as well as propane, were examined. Temporal changes between the different cookstove burn‐phases were also explored. Normalized concentrations of non‐refractory PM1, total organics, chloride, ammonium, nitrate, sulfate, and 41 particle‐phase polycyclic aromatic hydrocarbons (PAHs) were measured using a High‐Resolution Time‐of‐Flight Aerosol Mass Spectrometer (HR‐ToF‐AMS) and a Thermal desorption Aerosol Gas chromatograph (TAG), respectively. Coal demonstrated the highest fraction of organic matter in its particulate emission composition (98%), followed by dung (94%). Coal and dung also demonstrated the highest numbers and concentrations of PAHs. While dry applewood emitted ten times lower organic matter compared to ambient applewood, a higher fraction of these organics was composed of PAHs, especially the more toxic ones such as benzo(a)pyrene (9.63 ng/L versus 0.04 ng/L), and benzo(b)fluoranthene (31.32 ng/L versus 0.19 ng/L). Data from the AMS demonstrated no clear trends for any of the combustion fuels over the different combustion phases unlike the previously reported trends observed for the physical characteristics. Of the solid fuels, pellets demonstrated the lowest emissions. Emissions from propane were below the quantification limit of the instruments. This work highlights the benefits of incorporating additional metrics into the cookstove evaluation process, thus enriching the existing PM data inventory. Graphical abstract Figure. No Caption available. HighlightsThe chemical composition of particulate matter from 4 solid fuels and propane were examined.On‐line data were collected using a HR‐ToF‐AMS and TAG GC‐MS.Coal and dung exhibited the highest fractions of organic matter in their particulate emissions.Dry applewood emitted fewer organics compared to ambient applewood, but a higher fraction of PAHs.Of the solid fuels, pellets demonstrated the lowest emissions, and propane was below detection.

Thermal Modeling for a HVAC Controlled Real-Life Auditorium

The largest source of energy consumption in buildings is heating, ventilation, and air conditioning (HVAC). For an HVAC system to provide comfort and minimize energy consumption, it is crucial to understand the spatiotemporal thermal dynamics, especially in large open spaces. To optimize HVAC control, it is important to establish accurate dynamic thermal models. For this purpose, we constructed a real-world test bed by instrumenting an HVAC-controller auditorium using multiple types of sensors. Based on the dataset, we develop and evaluate a novel data-driven approach to model the complex thermal dynamics in a large space through a combination of data clustering and system identification techniques. Real-world data shows that our approach achieves low estimation errors. Our modeling approach therefore provides a practical foundation for HVAC control and optimization for large open spaces.

Characterization of Aerosols Generated During Patient Care Activities

Summary Measurement of the aerosols generated during 7 healthcare procedures showed an increase in particle concentrations over baseline only during nebulized medication administration (NMA) and bronchoscopy with NMA. Recovered bacteria were common environmental organisms.

Comparing on-road real-time simultaneous in-cabin and outdoor particulate and gaseous concentrations for a range of ventilation scenarios

Advanced automobile technology, developed infrastructure, and changing economic markets have resulted in increasing commute times. Traffic is a major source of harmful pollutants and consequently daily peak exposures tend to occur near roadways or while traveling on them. The objective of this study was to measure simultaneous real-time particulate matter (particle numbers, lung-deposited surface area, PM2.5, particle number size distributions) and CO concentrations outside and in-cabin of an on-road car during regular commutes to and from work. Data was collected for different ventilation parameters (windows open or closed, fan on, AC on), whilst traveling along different road-types with varying traffic densities. Multiple predictor variables were examined using linear mixed-effects models. Ambient pollutants (NOx, PM2.5, CO) and meteorological variables (wind speed, temperature, relative humidity, dew point) explained 5-44% of outdoor pollutant variability, while the time spent travelling behind a bus was statistically significant for PM2.5, lung-deposited SA, and CO (adj-R2 values = 0.12, 0.10, 0.13). The geometric mean diameter (GMD) for outdoor aerosol was 34 nm. Larger cabin GMDs were observed when windows were closed compared to open (b = 4.3, p-value = <0.01). When windows were open, cabin total aerosol concentrations tracked those outdoors. With windows closed, the pollutants took longer to enter the vehicle cabin, but also longer to exit it. Concentrations of pollutants in cabin were influenced by outdoor concentrations, ambient temperature, and the window/ventilation parameters. As expected, particle number concentrations were impacted the most by changes to window position / ventilation, and PM2.5 the least. Car drivers can expect their highest exposures when driving with windows open or the fan on, and their lowest exposures during windows closed or the AC on. Final linear mixed-effects models could explain between 88-97% of cabin pollutant concentration variability. An individual may control their commuting exposure by applying dynamic behavior modification to adapt to changing pollutant scenarios.

Comparing the performance of 3 bioaerosol samplers for influenza virus

Abstract Respiratory viral diseases can be spread when a virus-containing particle (droplet) from one individual is aerosolized and subsequently comes into either direct or indirect contact with another individual. Increasing numbers of studies are examining the occupational risk to healthcare workers due to proximity to patients. Selecting the appropriate air sampling method is a critical factor in assuring the analytical performance characteristics of a clinical study. The objective of this study was to compare the physical collection efficiency and virus collection efficiency of a 5mL compact SKC BioSampler®, a gelatin filter, and a glass fiber filter, in a laboratory setting. The gelatin filter and the glass fiber filter were housed in a home-made filter holder. Submersion (with vortexing and subsequent centrifugation) was used for the gelatin and glass fiber filters. Swabbing method was also tested to retrieve the viruses from the glass fiber filter. Experiments were conducted using the H1N1 influenza A virus A/Puerto Rico/8/1934 (IAV-PR8), and viral recovery was determined using culture and commercial real-time-PCR (BioFire and Xpert). An atomizer was used to aerosolize a solution of influenza virus in PBS for measurement, and two Scanning Mobility Particle Sizers were used to determine particle size distributions. The SKC BioSampler demonstrated a U-shaped physical collection efficiency, lowest for particles around 30–50nm, and highest at 10nm and 300–350nm within the size range examined. The physical collection efficiency of the gelatin filter was strongly influenced by air flow and time: a stable collection across all particle sizes was only observed at 2L/min for the 9min sampling time, otherwise, degradation of the filter was observed. The glass fiber filter demonstrated the highest physical collection efficiency (100% for all sizes) of all tested samplers, however, its overall virus recovery efficiency fared the worst (too low to quantify). The highest viral collection efficiencies for the SKC BioSampler and gelatin filter were 5% and 1.5%, respectively. Overall, the SKC BioSampler outperformed the filters. It is important to consider the total concentration of viruses entering the sampler when interpreting the results.

Defining Aerosol Generating Procedures and Pathogen Transmission Risks in Healthcare Settings

Abstract Background Questions remain about the degree to which small particle aerosols are generated during patient care activities and whether such aerosols could transmit viable pathogens to healthcare personnel. This project measured aerosol production during common medical procedures and collected samples for pathogen recovery. Methods Six procedures were targeted for aerosol sampling: extubation, bronchoscopy, mechanical ventilation, noninvasive ventilation, suctioning (open or tracheostomy), and nebulized medication administration. Any patient undergoing one of these procedures was eligible for sampling, with a preference for patients with a respiratory viral infection. Baseline samples were collected when possible. Four real-time aerosol characterization instruments were used to detect small particle aerosols generated during procedures. SKC Biosamplers, placed at 3 feet and 6 feet from the patient, were used for pathogen recovery. All samples were subjected to bacterial culture; viral PCR, and viral culture were added depending on the patient’s respiratory disease profile. Results Samples were collected during extubation (n = 1), bronchoscopy (n = 3), mechanical ventilation (n = 13), noninvasive ventilation (n = 6), suctioning (n = 6), and nebulized medication administration (n = 9). Only nebulized medication administration exhibited differences in particle mass concentration between baseline and procedure aerosol measurements. None of the Biosampler samples were PCR positive for a respiratory virus and none had a positive influenza culture. Five samples had positive bacterial cultures, mainly with common environmental or skin contaminants such as Micrococcus luteus, Staphylococcus pasturei, and Bacillus flexus. Conclusion Significant small particle aerosol generation was only seen with nebulized medication administration. No viruses were recovered and minimal viable bacteria were recovered. Additional study is needed to confirm these findings and examine aerosol generation during other procedures commonly considered to be aerosol-generating. Disclosures C. A. D. Burnham, bioMerieux: Grant Investigator, Research grant; ThermoFisher: Consultant, Salary; Cepheid: Grant Investigator, Research grant

Associations between household air pollution and reduced lung function in women and children in rural southern India: ASSOCIATIONS BETWEEN HOUSEHOLD AIR POLLUTION AND LUNG FUNCTION

Half of the worlds population still relies on solid fuels to fulfill its energy needs for cooking and space heating, leading to high levels of household air pollution (HAP), adversely affecting human health and the environment. A cross‐sectional cohort study was conducted to investigate any associations between: (1) HAP metrics (mass concentration of particulate matter of aerodynamic size less than 2.5 μm (PM2.5), lung‐deposited surface area (LDSA) and carbon monoxide (CO)); (2) a range of household and socio‐demographic characteristics; and (3) lung function for women and children exposed daily to biomass cookstove emissions, in rural southern India. HAP measurements were collected inside the kitchen of 96 households, and pulmonary function tests were performed for the women and child in each enrolled household. Detailed questionnaires captured household characteristics, health histories and various socio‐demographic parameters. Simple linear and logistic regression analysis was performed to examine possible associations between the HAP metrics, lung function and all household/socio‐demographic variables. Obstructive lung defects (forced vital capacity (FVC) ≥ lower limit of normal (LLN) and forced expiratory volume in 1 second (FEV1)/FVC < LLN) were found in 8% of mothers and 9% of children, and restrictive defects (FVC < LLN and FEV1/FVC ≥ LLN) were found in 17% of mothers and 15% of children. A positive association between LDSA, included for the first time in this type of epidemiological study, and lung function was observed, indicating LDSA is a superior metric compared to PM2.5 to assess effects of PM on lung function. HAP demonstrated a moderate association with subnormal lung function in children. The results emphasize the need to look beyond mass‐based PM metrics to assess fully the association between HAP and lung function.