Alan Rossner

PM2.5 and ultrafine particles emitted during heating of commercial cooking oils.

UNLABELLED Seven commercial cooking oils were investigated to determine the PM(2.5) mass and ultrafine particle (UFP) emission rates and emission fluxes (rates per area). The results of this study showed that at 197°C soybean, safflower, canola, and peanut oils produced lower PM(2.5) emission fluxes (6.1 × 10(5), 3.0 × 10(5), 5.4 × 10(5), and 3.9 × 10(5) μg/min/m(2), respectively) than corn, coconut, and olive oils (2.7 × 10(6), 2.9 × 10(6), and 5.7 × 10(6) μg/min/m(2), respectively). Similarly, the total particle number flux at 197°C was lower for soybean, safflower, and canola oils (3.5 × 10(13), 8.6 × 10(13), and 1.0 × 10(14) #/min/m(2), respectively) than the corn, coconut, olive, and peanut oils (2.4 × 10(14), 1.4 × 10(14), 1.7 × 10(14), and 3.8 × 10(14) #/min/m(2), respectively). In general, oils with a higher smoke temperature resulted in lower particle concentrations over the measured temperature range (131-197°C). The percentage of UFP (particle diameter D(p) 10-100 nm) to total particles (D(p) 10-500 nm) ranged from 76 to 99% for this temperature range. Particles below 10 nm in diameter were not measured. The particle number size distribution showed a polydisperse behavior with major mode sizes ranging from 25 nm (for peanut oil) to 82 nm (for soybean oil) at an oil temperature of 197°C. PRACTICAL IMPLICATIONS The study presents particle number and mass concentrations, size distributions, emission rates, and emission fluxes from heating common cooking oils. The emission rates and emission fluxes can be used as inputs to models for indirect exposure analysis studies. The study may also be used to provide guidance on choosing oils that result in lower emission rates when heated.

Seasonal and diurnal variability in airborne mold from an indoor residential environment in northern New York.

Abstract It is well known that characterization of airborne bioaerosols in indoor environments is a challenge because of inherent irregularity in concentrations, which are influenced by many environmental factors. The primary aim of this study was to quantify the day-to-day variability of airborne fungal levels in a single residential environment over multiple seasons. Indoor air quality practitioners must recognize the inherent variability in airborne bio-aerosol measurements during data analysis of mold investigations. Changes in airborne fungi due to varying season and day is important to recognize when considering health impacts of these contaminants and when establishing effective controls. Using an Andersen N6 impactor, indoor and outdoor bioaerosol samples were collected on malt extract agar plates for 18 weekdays and 19 week-days in winter and summer, respectively. Interday and intraday variability for the bioaerosols were determined for each sampler. Average fungal concentrations were 26 times higher during the summer months. Day-to-day fungal samples showed a relatively high inconsistency suggesting airborne fungal levels are very episodic and are influenced by several environmental factors. Summer bio-aerosol variability ranged from 7 to 36% and winter variability from 24 to 212%; these should be incorporated into results of indoor mold investigations. The second objective was to observe the relationship between biological and nonbiological particulate matter (PM). No correlation was observed between biological and nonbiological PM. Six side-by-side particulate samplers collected coarse PM (PM10) and fine PM (PM2.5) levels in both seasons. PM2.5 particulate concentrations were found to be statistically higher during summer months. Interday variability observed during this study suggests that indoor air quality practitioners must adjust their exposure assessment strategies to reflect the temporal variability in bioaerosol concentrations.

Preliminary assessment of a model to predict mold contamination based on microbial volatile organic compound profiles

Identification of mold growth based on microbial volatile organic compounds (MVOCs) may be a viable alternative to current bioaerosol assessment methodologies. A feed-forward back propagation (FFBP) artificial neural network (ANN) was developed to correlate MVOCs with bioaerosol levels in built environments. A cross-validation MATLAB script was developed to train the ANN and produce model results. Entech Bottle-Vacs were used to collect chemical grab samples at 10 locations in northern NY during 17 sampling periods from July 2006 to August 2007. Bioaerosol samples were collected concurrently with chemical samples. An Anderson N6 impactor was used in conjunction with malt extract agar and dichloran glycerol 18 to collect viable mold samples. Non-viable samples were collected with Air-O-Cell cassettes. Chemical samples and bioaerosol samples were used as model inputs and model targets, respectively. Previous researchers have suggested the use of MVOCs as indicators of mold growth without the use of a pattern recognition program limiting their success. The current proposed strategy implements a pattern recognition program making it instrumental for field applications. This paper demonstrates that FFBP ANN may be used in conjunction with chemical sampling in built environments to predict the presence of mold growth.

Evaluation of an Air Sampling Technique for Assessing Low-Level Volatile Organic Compounds in Indoor Environments

Abstract Measuring trace levels of volatile organic compounds (VOCs) in indoor environments is important for the characterization of occupant exposures. The ability to quickly collect air samples at relatively low costs per sample can increase the number of samples that can be collected and thus improve the overall assessment of potential exposures. The specific goal of this paper is to evaluate the accuracy and precision of evacuated glass bottle air samplers (Entech Bottle-Vacs) to collect representative VOC samples at part-per-billion concentrations in indoor environments. Laboratory generated data are also included to validate the precision and accuracy of the method. Multiple Bottle-Vacs in 10 residences in northern New York over 18 different sampling periods were used to collect whole-air VOC samples. Percent relative standard deviations ranged from 1.2 to 20.3% with a median of 8.8% for the 21 compounds analyzed in each Bottle-Vac. Two sampling techniques were used: around the valve (ATV) and through the valve (TTV). Linear regressions of ATV and TTV sample collection into the Bottle-Vacs show that these two sampling techniques are reproducible. Paired t test results show that ATV sampling is more reproducible than TTV; ATV paired samples were statistically the same 100% of the time whereas TTV paired samples were statistically the same 76.9% of the time. ATV sampling of low-level VOCs in indoor built environments is a reproducible chemical sampling technique that could be used by building occupants as a quick and inexpensive means of area sampling.

A Novel Personal Air Sampling Device for Collecting Volatile Organic Compounds: A Comparison to Charcoal Tubes and Diffusive Badges

Evacuated canisters have been used for many years to collect ambient air samples for gases and vapors. Recently, significant interest has arisen in using evacuated canisters for personal breathing zone sampling as an alternative to sorbent sampling. A novel flow control device was designed and built at McGill University. The flow control device was designed to provide a very low flow rate, < 0.5 mL/min, to allow a sample to be collected over an extended period of time. Previous experiments run at McGill have shown agreement between the mathematical and empirical models to predict flow rate. The flow control device combined with an evacuated canister (capillary flow control-canister) was used in a series of experiments to evaluate its performance against charcoal tubes and diffusive badges. Air samples of six volatile organic compounds were simultaneously collected in a chamber using the capillary flow control-canister, charcoal tubes, and diffusive badges. Five different concentrations of the six volatile organic compounds were evaluated. The results from the three sampling devices were compared to each other and to concentration values obtained using an online gas chromatograph (GC). Eighty-four samples of each method were collected for each of the six chemicals. Results indicate that the capillary flow control-canister device compares quite favorably to the online GC and to the charcoal tubes, p > 0.05 for most of the tests. The capillary flow control-canister was found to be more accurate for the compounds evaluated, easier to use, and easier to analyze than charcoal tubes and passive dosimeter badges.

Source apportionment of benzene downwind of a major point source

Abstract In the United States, the Emergency Planning and Community Right–to–Know Act requires sources that emit more than their Threshold Planning Quantity (TPQ) must publically report their total annual emissions. Because these values are aggregated over an entire year, high total emissions are often reported in the toxic release inventory. The Akwesasne Mohawk Reservation in rural Northern New York State lies downwind of an industrial source that reported annual benzene emissions of approximately 29 000 pounds. To assess if these emissions contributed significantly to the ambient concentrations, 24 hour canister samples were collected every 6th day from May 30 2007 to July 12 2008 at 9 locations on the Reservation. The samples were analyzed for benzene, toluene, ethyl benzene, and xylenes (BTEX) by GC/FID/MS using EPA Method TO15 procedures. In addition, gasoline samples (6 regular unleaded, 2 midgrade unleaded and 2 super unleaded) were collected in December 2007, May 2008 and July 2008 from five gas stations. The concentrations of BTEX in each gasoline sample were determined by headspace analysis. Vehicle tailpipe sampling was conducted by directly collecting samples from the tailpipe into Tedlar bags on 5 days: March 26, 2008, April 24, 2008, May 8, 2008, May 29, 2008 and June 12, 2008. Three samples were collected from each of the 22 vehicles that were fueled with unleaded regular gasoline from the reservation. Using these measured source profiles and ambient concentrations, the Chemical Mass Balance model was applied to each sample to assess the source contributions of BTEX. The results show that the predominant benzene source is vehicular exhaust with a small contribution from gasoline volatilization. The industrial plant has little or no impact on the ambient benzene concentrations in this community.

Monitoring of carbon monoxide in residences with bulk wood pellet storage in the Northeast United States

ABSTRACT The interest in biomass fuel is continuing to expand globally and in the northeastern United States as wood pellets are becoming a primary source of fuel for residential and small commercial systems. Wood pellets for boilers are often stored in basement storage rooms or large bag-type containers. Due to the enclosed nature of these storage areas, the atmosphere may exhibit increased levels of carbon monoxide. Serious accidents in Europe have been reported over the last decade in which high concentrations of carbon monoxide (CO) have been found in or near bulk pellet storage containers. The aim of this study was to characterize the CO concentrations in areas with indoor storage of bulk wood pellets. Data was obtained over approximately 7 months (December 2013 to June 2014) at 25 sites in New Hampshire and Massachusetts: 16 homes using wood pellet boilers with indoor pellet storage containers greater than or equal to 3 ton capacity; 4 homes with wood pellet heating systems with outdoor pellet storage; 4 homes using other heating fuels; and a university laboratory site. CO monitors were set up in homes to collect concentrations of CO in the immediate vicinity of wood pellet storage containers, and data were then compared to those of homes using fossil fuel systems. The homes monitored in this study provided a diverse set of housing stock spanning two and a half centuries of construction, with homes built from 1774 to 2013, representing a range of air exchange rates. The CO concentration data from each home was averaged hourly and then compared to a threshold of 9 ppm. While concentrations of CO were generally low for the homes studied, the need to properly design storage locations for pellets is and will remain a necessary component of wood pellet heating systems to minimize the risk of CO exposure. Implications: This paper is an assessment of carbon monoxide (CO) exposure from bulk wood pellet storage in homes in New Hampshire and Massachusetts. Understanding the CO concentrations in homes allows for better designs for storage bins and ventilation for storage areas. Hence, uniform policies for stored wood pellets in homes, schools, and businesses can be framed to ensure occupant safety. Currently in New York State rebates for the installation of wood pellet boilers are only provided if the bulk pellet storage is outside of the home, yet states such as New Hampshire, Vermont, and Maine currently do not have these restrictions.

Occupational exposure of aldehydes resulting from the storage of wood pellets

ABSTRACT An exposure assessment was conducted to investigate the potential for harmful concentrations of airborne short chain aldehydes emitted from recently stored wood pellets. Wood pellets can emit a number of airborne aldehydes include acetaldehyde, formaldehyde, propionaldehyde, butyraldehyde, valeraldehyde, and hexanal. Exposure limits have been set for these compounds since they can result in significant irritation of the upper respiratory system at elevated concentrations. Formaldehyde is a recognized human carcinogen and acetaldehyde is an animal carcinogen. Thus, air sampling was performed in a wood pellet warehouse at a pellet mill, two residential homes with bulk wood pellet storage bins, and in controlled laboratory experiments to evaluate the risk to occupants. Using NIOSH method 2539, sampling was conducted in five locations in the warehouse from April–June 2016 when it contained varying quantities of bagged pellets as well as two homes with ten ton bulk storage bins. The aldehyde concentrations were found to increase with the amount of stored pellets. Airborne concentrations of formaldehyde were as high as 0.45 ppm in the warehouse exceeding the NIOSH REL-C, and ACGIH TLV-C occupational exposure limits (OELs). The concentrations of aldehydes measured in the residential bins were also elevated indicating emissions may raise indoor air quality concerns for occupants. While individual exposures are of concern the combined irritant effect of all the aldehydes is a further raise the concerns for building occupants. To minimize exposure and the risk of adverse health effects to a buildings occupants in storage areas with large quantities of pellets, adequate ventilation must be designed into storage areas.

A Field Study to Assess the Long-Term Sampling Feasibility of Evacuated Canisters and the Development of a Mathematical Model to Analyze Potential Sampling Bias

Small, evacuated canisters (300 mL) equipped with a unique capillary flow controller were used to evaluate airborne concentrations of Stoddard solvent. The physical characteristics of the flow controller permitted the collection of air samples for a time period of 40 hours (5 consecutive work days). Long-term sampling (greater than 8 hours) is rarely performed in industrial hygiene due to limitations in current air sampling technology but may provide valuable information in characterizing worker cumulative exposures for some processes. A field study was performed to evaluate the feasibility of collecting a 40-hour area sample using the small canisters. Six canister samplers were used as area monitors to evaluate a cleaning operation for an entire workweek. For comparison, 30 diffusive badges (6 per day) were simultaneously used to monitor the same process. No statistical difference was found between the time-weighted average for the two sampling methods (p > 0.05). In addition, the canister samples integrate airborne concentrations for an entire workweek and therefore peak concentrations are not explicitly observed. Thus, an examination of peak exposures using simulated concentrations was conducted. A mathematical model was developed to determine whether a significant sampling bias was associated with long-term canister sampling when peak concentrations are present. The maximum possible bias was determined to be less than 9% for peak amplitudes having 10 times the background concentration and well below that for smaller amplitudes. Long-term sampling with the small, evacuated canisters was found to provide results comparable to sorbent sampling methods but with the added benefit of a significantly increased sampling time.

Particle nucleation in a forested environment

Atmospheric nucleation is now recognized to be an important source of ambient particles. In this study, ground–based measurements using a tower were used to observe new particle formation in the Morgan Monroe State Forest (MMSF) in Southwestern Indiana in May 2008. Nucleation was observed at MMSF on a number of days through examination of the particle size distributions. Most of these events were nucleation and growth events that are typical of regional nucleation phenomena. The particle size and sulfuric acid concentration data were used to investigate the mechanism for the observed nucleation events. Four of the ten observed nucleation events were clearly the result of activation of pre–existing clusters. The others seem likely to be the result of classical ternary nucleation.