Indoor Emissions from Conversion Varnishes

ABSTRACT

Conversion varnishes are two-component, acid-catalyzed varnishes that are commonly used to finish cabinets. They are valued for their water and stain resistance, as well as their appearance. They have been found, however, to contribute to indoor emissions of organic compounds. For this project, three commercially available conversion varnish systems were selected. A U.S. Environmental Protection Agency (EPA) Method 24 analysis was performed to determine total volatile content, and a sodium sulfite titration method was used to determine uncombined (free) formaldehyde content of the varnish components. The resin component was also analyzed by gas chromatography/mass spectroscopy (GC/MS) (EPA Method 311 with an MS detector) to identify individual organic compounds. Dynamic small chamber tests were then performed to identify and quantify emissions following application to coupons of typical kitchen cabinet wood substrates, during both curing and aging. Because conversion varnishes cure by chemical reaction, the compounds emitted during curing and aging are not necessarily the same as those in the formulation. Results of small chamber tests showed that the amount of formaldehyde emitted from these coatings was 2.3–8.1 times the amount of free formaldehyde applied in the coatings. A long-term test showed a formaldehyde emission rate of 0.17 mg/m²/hr after 115 days.     

Performance and Diagnostic Evaluation of Ozone Predictions by the Eta-Community Multiscale Air Quality Forecast System during the 2002 New England Air Quality Study

Abstract

A real-time air quality forecasting system (Eta-Community Multiscale Air Quality [CMAQ] model suite) has been developed by linking the National Centers for Environmental Estimation Eta model to the U.S. Environmental Protection Agency (EPA) CMAQ model. This work presents results from the application of the Eta-CMAQ modeling system for forecasting ozone (O₃) over the Northeastern United States during the 2002 New England Air Quality Study (NEAQS). Spatial and temporal performance of the Eta-CMAQ model for O₃ was evaluated by comparison with observations from the EPA Air Quality System (AQS) network. This study also examines the ability of the model to simulate the processes governing the distributions of tropospheric O₃ on the basis of the intensive datasets obtained at the four Atmospheric Investigation, Regional Modeling, Analysis, and Estimation (AIRMAP) and Harvard Forest (HF) surface sites. The episode analysis reveals that the model captured the buildup of O₃ concentrations over the northeastern domain from August 11 and reproduced the spatial distributions of observed O₃ very well for the daytime (8:00 p.m.) of both August 8 and 12 with most of normalized mean bias (NMB) within [H11006]20%. The model reproduced 53.3% of the observed hourly O₃ within a factor of 1.5 with NMB of 29.7% and normalized mean error of 46.9% at the 342 AQS sites.The comparison of modeled and observed lidar O₃ vertical profiles shows that whereas the model reproduced the observed vertical structure, it tended to overestimate at higher altitude. The model reproduced 64 –77% of observed NO₂ photolysis rate values within a factor of 1.5 at the AIRMAP sites. At the HF site, comparison of modeled and observed O₃/nitrogen oxide (NO_x) ratios suggests that the site is mainly under strongly NO_x-sensitive conditions (>53%). It was found that the modeled lower limits of the O₃ production efficiency values (inferred from O₃-CO correlation) are close to the observations.     

Application of a Combined Measurement and Modeling Method to Quantify Windblown Dust Emissions from the Exposed Playa at Mono Lake,California

ABSTRACT

Particulate matter ≤10 μm (PM₁₀) emissions due to wind erosion can vary dramatically with changing surface conditions. Crust formation, mechanical disturbance, soil texture, moisture, and chemical content of the soil can affect the amount of dust emitted during a wind event. A refined method of quantifying windblown dust emissions was applied at Mono Lake, CA, to account for changing surface conditions. This method used a combination of real-time sand flux monitoring, ambient PM₁₀ monitoring, and dispersion modeling to estimate dust emissions and their downwind impact. The method identified periods with high emissions and periods when the surface was stable (no sand flux), even though winds may have been high. A network of 25 Cox sand catchers (CSCs) was used to measure the mass of saltating particles to estimate sand flux rates across a 2-km² area. Two electronic sensors (Sensits) were used to time-resolve the CSC sand mass to estimate hourly sand flux rates, and a perimeter tapered element oscillating microbalance (TEOM) monitor measured hourly PM₁₀ concentrations. Hourly sand flux rates were related by dispersion modeling to hourly PM₁₀ concentrations to back-calculate the ratio of vertical PM₁₀ flux to horizontal sand flux (K-factors). Geometric mean K-factor values (K _f) were found to change seasonally, ranging from 1.3 × 10^?5 to 5.1 × 10^?5 for sand flux measured at 15 cm above the surface (q ₁₅). Hourly PM₁₀ emissions, F, were calculated by applying seasonal K-factors to sand flux measurements (F?=?K _f ×?q ₁₅). The maximum hourly PM10 emission rate from the study area was 76 g/m²·hr (10-m wind speed?=?23.5 m/sec). Maximum daily PM₁₀ emissions were estimated at 450 g/m²·day, and annual emissions at 1095 g/m²·yr. Hourly PM₁₀ emissions were used by the U.S. Environmental Protection Agency (EPA) guideline AERMOD dispersion model to estimate downwind ambient impacts. Model predictions compared well with monitor concentrations, with hourly PM₁₀ ranging from 16 to over 60,000 μg/m³ (slope?=?0.89, R ²?=?0.77).

IMPLICATIONS Under a U.S. Environmental Protection Agency (EPA)-approved plan, the method described in this paper has been used since 2000 at Owens Lake, CA, to identify and successfully mitigate dust from over 100 km² of the dry lakebed. It continues to be used to monitor dust control compliance at Owens Lake. Scaled-down versions of the Owens Lake network can be implemented in other areas in a manner similar to the Mono Lake study. Once K-factors are established, low-cost CSC samplers (about $35 U.S.) may be used for periodic monitoring (e.g., daily, weekly, or monthly) to estimate PM₁₀ emissions or to evaluate dust control compliance.     

Long-Term Field Characterization of Tapered Element Oscillating Microbalance and Modified Tapered Element Oscillating Microbalance Samplers in Urban and Rural New York State Locations

Abstract

Long-term field comparisons of continuous and integrated filter measurements of mass concentrations of par-ticulate matter (PM) with an aerodynamic diameter less than or equal to 2.5 μm (PM_2.5) were performed at rural and urban sites in New York State. Two versions of the continuous tapered element oscillating microbalance (TEOM) mass monitor are deployed at each site, in addition to Federal Reference Method filter samplers. Data are grouped into monthly averages to retain and demonstrate seasonal differences. Strong seasonal dependence is observed—the TEOM monitors with the heated sensors are biased systematically low with respect to the Federal Reference Method measurements during the cold season. For the rural site, the average bias for the sample equilibration system (SES)-equipped and standard TEOM monitors is 14 and 24%, respectively. At this location, the TEOM monitor measurements were biased low for all 34 months. For the urban site, the average bias for the SES and standard TEOM monitors is 8 and 18%, respectively. At this location, the TEOM monitor measurements are as likely to be biased high as low during the warm-season months. The hour averaged data from the two versions of the TEOM monitor are also compared, and also indicate that the SES-equipped version of the TEOM monitor captures 7-11% more PM_2.5 mass at these locations.     

Laboratory Characterization of Modified Tapered Element Oscillating Microbalance Samplers

Abstract

Laboratory tests with generated aerosols were conducted to test the efficacy of two recent design modifications to the well-established tapered element oscillating microbalance (TEOM) continuous particulate matter (PM) mass monitor. The two systems tested were the sample equilibration system-equipped TEOM monitor operating at 30 °C, which uses a Nafion dryer as part of the sample inlet, and the differential TEOM monitor, which adds a switched electrostatic precipitator and uses a self-referencing algorithm to determine “true PM mass.” Test aerosols included ammonium sulfate, ammonium nitrate, sodium chloride, copper (II) sulfate, and mixed aerosols. Aerosols were generated with an atomizer or a vibrating orifice generator and were equilibrated in a 450-L slow flow chamber before being sampled. Relative humidity in the chamber was varied between 10 and 90%, and step changes in humidity were executed while generating aerosol to test the response of the instruments. The sample equilibration system-equipped TEOM monitor does reduce, but not totally eliminate, the sensitivity of the TEOM mass monitor to changes in humidity. The differential TEOM monitor gives every indication of being a very robust technique for the continuous real-time measurement of ambient aerosol mass, even in the presence of semi-volatile particles and condensable gases.     

An 'artificial mussel' for monitoring heavy metals in marine environments

A new chemical sampling device, artificial mussel (AM), has been developed for monitoring metals in marine environments. This device consists of a polymer ligand suspended in artificial seawater within a Perspex tubing, and enclosed with semi-permeable gel at both ends. Laboratory and field experiments were carried out to examine the uptake of five metals (Cd, Cr, Cu, Pb and Zn) by the AM. Uptake of metals by AM was proportional to the exposure metal concentrations, and the AM was able to accumulate the ASV labile fractions of metals. Uptake and release of the metals of AM are similar to those of the mussel Perna viridis, but less affected by salinity and temperature. Field studies demonstrated that the AM can not only provide a time-integrated estimate of metals concentrations, but also allows comparisons of metal levels in different environments and geographical areas beyond the natural distribution limits of biomonitors.     

Evaluation of quicklime incorporation in bench-scale and full-scale lime stabilized biosolids using a flat surface pH electrode

Uniform lime incorporation into sewage sludge is critical for biosolid lime stabilization processes. There is no class B biosolids regulation for lime incorporation. The slurry method is currently used to evaluate the pH of limed biosolids, but this method homogenizes the biosolids and potentially masks poor lime mixing. In this study, a flat-surface pH electrode was used in bench-scale and full-scale experiments to measure the pH of lime-stabilized biosolids without creating slurries. The standard deviation of 15 pH measurements at different locations in a biosolid sample was used to assess mixing quality. The bench-scale experimental study showed that well-mixed limed biosolids had consistently high pHs (approximately 12) with low standard deviations (< 0.5 pH units), whereas poorly mixed biosolids had areas with low pH (< 10) and high standard deviations (> 2 pH units). Poorly mixed biosolids exhibited rapid and marked pH reduction, as well as offensive odor generation, whereas well-mixed biosolids resisted pH reduction and offensive odor generation. The full-scale study aimed at improving lime incorporation and biosolids quality confirmed the use of a flat surface pH electrode to capture low pH regions in biosolids that were masked by the current slurry method.     

Estimating net changes in life-cycle emissions from adoption of emerging civil infrastructure technologies

There is a net emissions change when adopting new materials for use in civil infrastructure design. To evaluate the total net emissions change, one must consider changes in manufacture and associated life-cycle emissions, as well as changes in the quantity of material required. In addition, in principle one should also consider any differences in costs of the two designs because cost savings can be applied to other economic activities with associated environmental impacts. In this paper, a method is presented that combines these considerations to permit an evaluation of the net change in emissions when considering the adoption of emerging technologies/materials for civil infrastructure. The method factors in data on differences between a standard and new material for civil infrastructure, material requirements as specified in designs using both materials, and price information. The life-cycle assessment approach known as economic input-output life-cycle assessment (EIO-LCA) is utilized. A brief background on EIO-LCA is provided because its use is central to the method. The methodology is demonstrated with analysis of a switch from carbon steel to high-performance steel in military bridge design. The results are compared with a simplistic analysis that accounts for the weight reduction afforded by use of the high-performance steel but assuming no differences in manufacture.     

Synopsis of the temporal variation of particulate matter composition and size

A synopsis of the detailed temporal variation of the size and number distribution of particulate matter (PM) and its chemical composition on the basis of measurements performed by several regional research consortia funded by the U.S. Environmental Protection Agency (EPA) PM Supersite Program is presented. This program deployed and evaluated a variety of research and emerging commercial measurement technologies to investigate the physical and chemical properties of atmospheric aerosols at a level of detail never before achieved. Most notably these studies demonstrated that systematic size-segregated measurements of mass, number, and associated chemical composition of the fine (PM2.5) and ultrafine (PM0.1) fraction of ambient aerosol with a time resolution down to minutes and less is achievable. A wealth of new information on the temporal variation of aerosol has been added to the existing knowledge pool that can be mined to resolve outstanding research and policy-related questions. This paper explores the nature of temporal variations (on time scales from several minutes to hours) in the chemical and physical properties of PM and its implications in the identification of PM formation processes, and source attribution (primary versus secondary), the contribution of local versus transported PM and the development of effective PM control strategies. The PM Supersite results summarized indicate that location, time of day, and season significantly influence not only the mass and chemical composition but also the size-resolved chemical/elemental composition of PM. Ambient measurements also show that ultrafine particles have different compositions and make up only a small portion of the PM mass concentration compared with inhalable coarse and fine particles, but their number concentration is significantly larger than their coarse or fine counterparts. PM size classes show differences in the relative amounts of nitrates, sulfates, crustal materials, and most especially carbon as well as variations in seasonal and diurnal patterns.     

Changes in weather and climate extremes: State of knowledge relevant to air and water quality in the United States

Air and water quality are impacted by extreme weather and climate events on time scales ranging from minutes to many months. This review paper discusses the state of knowledge of how and why extreme events are changing and are projected to change in the future. These events include heat waves, cold waves, floods, droughts, hurricanes, strong extratropical cyclones such as nor'easters, heavy rain, and major snowfalls. Some of these events, such as heat waves, are projected to increase, while others, with cold waves being a good example, will decrease in intensity in our warming world. Each extreme's impact on air or water quality can be complex and can even vary over the course of the event.

Implications:

Because extreme weather and climate events impact air and water quality, understanding how the various extremes are changing and are projected to change in the future has ramifications on air and water quality management.