Particle Emission Rates Research Articles

Mote Cyclone Robber System Total Particulate Emission Factors and Rates for Cotton Gins: Method 17

This report is part of a project to characterize cotton gin emissions from the standpoint of stack sampling. The impetus behind this project was the urgent need to collect additional cotton gin emissions data to address current regulatory issues. A key component of this study was focused on Environmental Protection Agency (EPA) total particulate emission factors. There is no total particulate emission factor published for mote cyclone robber systems in the 1996 EPA AP-42. The objective of this study was to collect total particulate emission factor data for mote cyclone robber cleaning systems from cotton gins located in regions across the cotton belt using EPA-approved stack sampling methodology. The project plan included sampling seven cotton gins. Key factors for selecting specific cotton gins included: 1) facility location, 2) production capacity, 3) processing systems and 4) abatement technologies. Three gins with mote cyclone robber systems were sampled. The average production rate during testing for the three gins was 25.6 bales/h. The average mote cyclone robber system total particulate emission factor based on three tests (nine total test runs) was 0.050 kg/227-kg bale (0.111 lb/500-lb bale). The mote cyclone robber systems emission rate test averages ranged from 0.66 to 2.15 kg/h (1.46-4.74 lb/h).

Second Stage Mote System Total Particulate Emission Factors and Rates for Cotton Gins: Method 17

This report is part of a project to characterize cotton gin emissions from the standpoint of stack sampling. The impetus behind this project was the urgent need to collect additional cotton gin emissions data to address current regulatory issues. A key component of this study was focused on Environmental Protection Agency (EPA) total particulate emission factors. There is no total particulate emission factors published for 2nd stage mote systems in the 1996 EPA AP-42. The current AP-42 factor represents 1st and 2nd stage mote systems combined. The objective of this study was to collect total particulate emission factor data for 2nd stage mote systems from cotton gins located in regions across the cotton belt using EPA-approved stack sampling methodology. The project plan included sampling seven cotton gins. Key factors for selecting specific cotton gins included: 1) facility location, 2) production capacity, 3) processing systems and 4) abatement technologies. Five gins with 2nd stage mote system exhausts that were not combined with 1st stage system exhausts were sampled. The average production rate during testing for the five gins was 29.5 bales/h. The average 2nd stage mote system total particulate emission factor based on five tests (15 total test runs) was 0.011 kg/227-kg bale (0.023 lb/500-lb bale). The test average 2nd stage mote system emission rates ranged from 0.16 to 0.71 kg/h (0.34-1.56 lb/h).

Third Stage Seed-Cotton Cleaning System Total Particulate Emission Factors and Rates for Cotton Gins: Method 17

This report is part of a project to characterize cotton gin emissions from the standpoint of stack sampling. The impetus behind this project was the urgent need to collect additional cotton gin emissions data to address current regulatory issues. A key component of this study was focused on Environmental Protection Agency (EPA) total particulate emission factors. EPA AP-42 emission factors generally are assigned a rating, from A (excellent) to E (poor), to assess the quality of the data being referenced. Current EPA total particulate emission factor ratings for cotton gins are extremely low. Cotton gin data received these low ratings because the data were collected almost exclusively from a single geographical region. The objective of this study was to collect additional total particulate emission factor data for 3rd stage seed-cotton cleaning systems from cotton gins located in regions across the cotton belt using EPA-approved stack sampling methodology. The project plan included sampling seven cotton gins. Key factors for selecting specific cotton gins included: 1) facility location, 2) production capacity, 3) processing systems, and 4) abatement technologies. Two gins with 3rd stage seed-cotton cleaning system exhausts were sampled. The average production rate during testing for the two gins was 21.0 bales/h. The average 3rd stage seed-cotton cleaning system total particulate emission factor based on two tests (six total test runs) was 0.023 kg/227-kg bale (0.052 lb/500-lb bale). This average total particulate emission factor was less than that currently published in 1996 EPA AP-42, which was 0.043 kg/bale (0.095 lb/bale). The 3rd stage seed-cotton cleaning system test average emission rates ranged from 0.27 to 0.75 kg/h (0.59-1.66 lb/h).

Mote Cleaner System Total Particulate Emission Factors and Rates for Cotton Gins: Method 17

This report is part of a project to characterize cotton gin emissions from the standpoint of stack sampling. The impetus behind this project was the urgent need to collect additional cotton gin emissions data to address current regulatory issues. A key component of this study was focused on Environmental Protection Agency (EPA) total particulate emission factors. There is no total particulate emission factor published for mote cleaner systems in the 1996 EPA AP-42. The objective of this study was to collect total particulate emission factor data for mote cleaner systems from cotton gins located in regions across the cotton belt using EPA-approved stack sampling methodology. The project plan included sampling seven cotton gins. Key factors for selecting specific cotton gins included: 1) facility location, 2) production capacity, 3) processing systems and 4) abatement technologies. Two gins with mote cleaner systems were sampled. The exhaust from one of the mote cleaner systems was combined with the module feeder dust system. The average production rate during testing was 32.7 and 47.0 bales/h for the stand alone mote cleaner system and mote cleaner and module feeder dust system, respectively. The average total particulate emission factor for the mote cleaner system that was not combined with another gin system (three total test runs) was 0.105 kg/227-kg bale (0.232 lb/500-lb bale). The average emission rate for this system was 3.46 kg/h (7.63 lb/h). The average total particulate emission factor for the mote cleaner system that was combined with the module feeder dust system (three total test runs) was 0.109 kg/bale (0.239 lb/bale). The average emission rate for this system was 5.10 kg/h (11.24 lb/h).

Combined Mote System Total Particulate Emission Factors and Rates for Cotton Gins

This report is part of a project to characterize cotton gin emissions from the standpoint of stack sampling. The impetus behind this project was the urgent need to collect additional cotton gin emissions data to address current regulatory issues. A key component of this study was focused on Environmental Protection Agency (EPA) total particulate emission factors. EPA AP-42 emission factors are generally assigned a rating, from A (Excellent) to E (Poor), to assess the quality of the data being referenced. Current EPA total particulate emission factor ratings for cotton gins are extremely low. Cotton gin data received these low ratings because the data were collected almost exclusively from a single geographical region. The objective of this study was to collect additional total particulate emission factor data for combined mote systems from cotton gins located in regions across the cotton belt using EPA-approved stack sampling methodology. The project plan included sampling seven cotton gins. Key factors for selecting specific cotton gins included: 1) facility location, 2) production capacity, 3) processing systems and 4) abatement technologies. Two gins with combined 1st and 2nd mote system exhausts were sampled. The average production rate during testing for the two gins was 33.7 bales/h. The average combined mote system total particulate emission factor based on two tests (six total test runs) was 0.146 kg/227-kg bale (0.321 lb/500-lb bale). This average total particulate emission factor was higher than that currently published in 1996 EPA AP-42, which was 0.13 kg/bale (0.28 lb/bale). The emission rate from test averages ranged from 3.45 to 6.45 kg/h (7.61-14.23 lb/h).

Second Stage Seed-Cotton Cleaning System Total Particulate Emission Factors and Rates for Cotton Gins: Method 17

This report is part of a project to characterize cotton gin emissions from the standpoint of stack sampling. The impetus behind this project was the urgent need to collect additional cotton gin emissions data to address current regulatory issues. A key component of this study was focused on Environmental Protection Agency (EPA) total particulate emission factors. EPA AP-42 emission factors generally are assigned a rating, from A (excellent) to E (poor), to assess the quality of the data being referenced. Current EPA total particulate emission factor ratings for cotton gins are extremely low. Cotton gin data received these low ratings because the data were collected almost exclusively from a single geographical region. The objective of this study was to collect additional total particulate emission factor data for 2nd stage seed-cotton cleaning systems from cotton gins located in regions across the cotton belt using EPA-approved stack sampling methodology. The project plan included sampling seven cotton gins. Key factors for selecting specific cotton gins included: 1) facility location, 2) production capacity, 3) processing systems, and 4) abatement technologies. Five gins with 2nd stage seed-cotton cleaning system exhausts were sampled. The average production rate during testing for the five gins was 34.7 bales/h. The average 2nd stage seed-cotton cleaning system total particulate emission factor based on five tests (14 total test runs) was 0.058 kg/227-kg bale (0.129 lb/500-lb bale). This average total particulate emission factor was less than that currently published in 1996 EPA AP-42, which was 0.11 kg/bale (0.24 lb/bale). The 2nd stage seed-cotton cleaning system test average emission rates ranged from 0.64 to 2.95 kg/h (1.41-6.49 lb/h).

First Stage Seed-Cotton Cleaning System Total Particulate Emission Factors and Rates from Cotton Gins: Method 17

This report is part of a project to characterize cotton gin emissions from the standpoint of stack sampling. The impetus behind this project was the urgent need to collect additional cotton gin emissions data to address current regulatory issues. A key component of this study was focused on Environmental Protection Agency (EPA) total particulate emission factors. EPA AP-42 emission factors generally are assigned a rating, from A (excellent) to E (poor), to assess the quality of the data being referenced. Current EPA total particulate emission factor ratings for cotton gins are extremely low. Cotton gin data received these low ratings because the data were collected almost exclusively from a single geographical region. The objective of this study was to collect additional total particulate emission factor data for 1st stage seed-cotton cleaning systems from cotton gins located in regions across the cotton belt using EPA-approved stack sampling methodology. The project plan included sampling seven cotton gins. Key factors for selecting specific cotton gins included: 1) facility location, 2) production capacity, 3) processing systems, and 4) abatement technologies. All seven gins had 1st stage seed-cotton cleaning systems. The average production rate during testing for the seven gins was 31.8 bales/h. The average 1st stage seed-cotton cleaning system total particulate emission factor based on seven tests (18 total test runs) was 0.152 kg/227-kg bale (0.334 lb/500-lb bale). This average total particulate emission factor was less than that currently published in 1996 EPA AP-42, which was 0.17 kg/bale (0.36 lb/bale). The 1st stage seed-cotton cleaning system emission rate test averages ranged from 1.87 to 8.93 kg/h (4.13-19.68 lb/h).

Cyclone Robber System Total Particulate Emission Factors and Rates for Cotton Gins: Method 17

This report is part of a project to characterize cotton gin emissions from the standpoint of stack sampling. The impetus behind this project was the urgent need to collect additional cotton gin emissions data to address current regulatory issues. A key component of this study was focused on Environmental Proctection Agency (EPA) total particulate emission factors. EPA AP-42 emission factors generally are assigned a rating, from A (excellent) to E (poor), to assess the quality of the data being referenced. Current EPA total particulate emission factor ratings for cotton gins are extremely low. Cotton gin data received these low ratings because the data were collected almost exclusively from a single geographical region. The objective of this study was to collect additional total particulate emission factor data for cyclone robber systems from cotton gins located in regions across the cotton belt using EPA-approved stack sampling methodology. The project plan included sampling seven cotton gins. Key factors for selecting specific cotton gins included: 1) facility location, 2) production capacity, 3) processing systems, and 4) abatement technologies. Three gins with cyclone robber system exhausts were sampled. The average production rate during testing for the three gins was 27.5 bales/h. The average cyclone robber system total particulate emission factor based on the three gins (12 total test runs) was 0.020 kg/227-kg bale (0.045 lb/500-lb bale). This average total particulate emission factor was less than that currently published in 1996 EPA AP-42, which was 0.083 kg/bale (0.18 lb/bale). The cyclone robber system test average emission rates ranged from 0.31 to 0.67 kg/h (0.69-1.48 lb/h).

First Stage Mote System Total Particulate Emission Factors and Rates for Cotton Gins: Method 17

This report is part of a project to characterize cotton gin emissions from the standpoint of stack sampling. The impetus behind this project was the urgent need to collect additional cotton gin emissions data to address current regulatory issues. A key component of this study was focused on Environmental Protection Agency (EPA) total particulate emission factors. There is no total particulate emission factor published for 1st stage mote systems in the 1996 EPA AP-42. The current AP-42 factor represents 1st and 2nd stage mote systems combined. The objective of this study was to collect total particulate emission factor data for 1st stage mote systems from cotton gins located in regions across the cotton belt using EPA-approved stack sampling methodology. The project plan included sampling seven cotton gins. Key factors for selecting specific cotton gins included: 1) facility location, 2) production capacity, 3) processing systems and 4) abatement technologies. Five gins with 1st stage mote system exhausts that were not combined with 2nd stage system exhausts were sampled. The average production rate during testing for the five gins was 27.9 bales/h. The average 1st stage mote system total particulate emission factor based on five tests (15 total test runs) was 0.025 kg/227-kg bale (0.056 lb/500-lb bale). The 1st stage mote system test average emission rates ranged from 0.31 to 1.42 kg/h (0.69-3.13 lb/h).

Combined Lint Cleaning System Total Particulate Emission Factors and Rates for Cotton Gins: Method 17

This report is part of a project to characterize cotton gin emissions from the standpoint of stack sampling. The impetus behind this project was the urgent need to collect additional cotton gin emissions data to address current regulatory issues. A key component of this study was focused on Environmental Protection Agency (EPA) total particulate emission factors. EPA AP-42 emission factors generally are assigned a rating, from A (excellent) to E (poor), to assess the quality of the data being referenced. Current EPA total particulate emission factor ratings for cotton gins are extremely low. Cotton gin data received these low ratings because the data were collected almost exclusively from a single geographical region. The objective of this study was to collect additional total particulate emission factor data for combined lint cleaning systems from cotton gins located in regions across the cotton belt using EPA-approved stack sampling methodology. The project plan included sampling seven cotton gins. Key factors for selecting specific cotton gins included: 1) facility location, 2) production capacity, 3) processing systems, and 4) abatement technologies. Three gins with combined 1st and 2nd stage lint cleaning system exhausts were sampled. The average production rate during testing for the seven gins was 32.6 bales/h. The average combined lint cleaning system total particulate emission factor based on three tests (nine total test runs) was 0.211 kg/227-kg bale (0.466 lb/500-lb bale). This average total particulate emission factor was less than that currently published in 1996 EPA AP-42, which was 0.26 kg/bale (0.58 lb/bale). The test average emission rates ranged from 2.04 to 12.39 kg/h (4.49-27.30 lb/h).

First Stage Lint Cleaning System Total Particulate Emission Factors and Rates for Cotton Gins: Method 17

This report is part of a project to characterize cotton gin emissions from the standpoint of stack sampling. The impetus behind this project was the urgent need to collect additional cotton gin emissions data to address current regulatory issues. A key component of this study was focused on Environmental Protection Agency (EPA) total particulate emission factors. There is no total particulate emission factor published for 1st stage lint cleaning systems in the 1996 EPA AP-42. The current AP-42 factor represents 1st and 2nd stage lint cleaning systems combined. The objective of this study was to collect total particulate emission factor data for 1st stage lint cleaning systems from cotton gins located in regions across the cotton belt using EPA-approved stack sampling methodology. The project plan included sampling seven cotton gins. Key factors for selecting specific cotton gins included: 1) facility location, 2) production capacity, 3) processing systems, and 4) abatement technologies. Four gins with 1st stage lint cleaning system exhausts that were not combined with 2nd stage lint cleaning system exhausts were sampled. The average production rate during testing for the four gins was 25.7 bales/h. The average 1st stage lint cleaning system total particulate emission factor based on four tests (12 total test runs) was 0.070 kg/227-kg bale (0.155 lb/500-lb bale). The 1st stage lint cleaning system emission rate test averages ranged from 0.67 to 3.56 kg/h (1.49-7.84 lb/h).

Geodesics in Generalized Painlevé-Gullstrand Coordinates and Tunneling Process from a Schwarzschild Black Hole

Using the null geodesics method in Painleve coordinates, Parikh and Wilczek calculated the emission rate of massless particles from a black hole. Afterwards, a series of works have been done concerning the tunneling process of massive particles, in which the timelike geodesics were not always calculated in a regular way. In this paper, taking the advantages of a conservative quantity, a general form of geodesics is given including both the timelike and the null ones in generalized Painleve-Gullstrand (PG-like) coordinates. Based on this, the derivation of Hawking radiation as a tunneling process is presented under the general form of geodesics. The results accorded well with the previous works.

Comment on "Reduced efficacy of marine cloud brightening geoengineering due to in-plume aerosol coagulation: parameterization and global implications" by Stuart et al. (2013)

Abstract. We examine the parameterized model of Stuart et al. (2013) vis-à-vis a diffusion-based model proposed by us earlier (Anand and Mayya, 2011) to estimate the fraction of aerosol particles surviving coagulation in a dispersing plume. While the Stuart et al. approach is based on the solutions to the coagulation problem in an expanding plume model, the diffusion-based approach solves the diffusion–coagulation equation for a steady-state standing plume to arrive at the survival fraction correlations. We discuss the differences in the functional forms of the survival fraction expressions obtained in the two approaches and compare the results for the case studies presented in Stuart et al. (2013) involving different particle emission rates and atmospheric stability categories. There appears to be a better agreement between the two models at higher survival fractions as compared to lower survival fractions; on the whole, the two models agree with each other within a difference of 10%. The diffusion-based expression involves a single exponent fit to a theoretically generated similarity variable combining the parameters of the problem with inbuilt exponents and hence avoids the multi-exponent parameterization exercise. It also possesses a wider range of applicability in respect of the source and atmospheric parameters as compared to that based on parameterization. However, in the diffusion model, the choice of a representative value for the coagulation coefficient is more prescriptive than rigorous, which has been addressed in a more satisfactory manner by the parameterization method. The present comparative exercise, although limited in scope, confirms the importance of aerosol microphysical processes envisaged by Stuart et al. for cloud brightening applications. In a larger context, it seems to suggest that either of the two forms of expressions might be suitable for incorporation into global-/regional-scale air pollution models for predicting the contribution of localized sources to the particle number loading in the atmosphere.

Characteristics of particulate matter emissions from toy cars with electric motors

Aerosol emissions from toy cars with electric motors were characterized. Particle emission rates from the toy cars, as high as 7.47 × 107 particles/s, were measured. This emission rate is lower than other indoor sources such as smoking and cooking. The particles emitted from toy cars are generated from spark discharges inside the electric motors that power the toy cars. Size distribution measurements indicated that most particles were below 100 nm in diameter. Copper was the dominant inorganic species in these particles. By deploying aerosol mass spectrometers, high concentrations of particulate organic matter were also detected and characterized in detail. Several organic compounds were identified using a thermal desorption aerosol gas chromatography. The mass size distribution of particulate organic matter was bimodal. The formation mechanism of particulate organic matter from toy cars was elucidated.Implications: A possible new source of indoor air pollution, particles from electric motors in toy cars, was identified. This study characterized aerosol emissions from toy cars in detail. Most of these particles have a diameter less than 100 nm. Copper and some organics are the major components of these particles. Conditions that minimize these emissions were determined.

Characterization of size-specific particulate matter emission rates for a simulated medical laser procedure--a pilot study.

Prior investigation on medical laser interaction with tissue has suggested device operational parameter settings influence laser generated air contaminant emission, but this has not been systematically explored. A laboratory-based simulated medical laser procedure was designed and pilot tested to determine the effect of laser operational parameters on the size-specific mass emission rate of laser generated particulate matter. Porcine tissue was lased in an emission chamber using two medical laser systems (CO2, λ = 10,600 nm; Ho:YAG, λ = 2100 nm) in a fractional factorial study design by varying three operational parameters (beam diameter, pulse repetition frequency, and power) between two levels (high and low) and the resultant plume was measured using two real-time size-selective particle counters. Particle count concentrations were converted to mass emission rates before an analysis of variance was used to determine the influence of operational parameter settings on size-specific mass emission rate. Particle shape and diameter were described for a limited number of samples by collecting particles on polycarbonate filters, and photographed using a scanning electron microscope (SEM) to examine method of particle formation. An increase in power and decrease in beam diameter led to an increase in mass emission for the Ho:YAG laser at all size ranges. For the CO2 laser, emission rates were dependent on particle size and were not statistically significant for particle ranges between 5 and 10 µm. When any parameter level was increased, emission rate of the smallest particle size range also increased. Beam diameter was the most influential variable for both lasers, and the operational parameters tested explained the most variability at the smallest particle size range. Particle shape was variable and some particles observed by SEM were likely created from mechanical methods. This study provides a foundation for future investigations to better estimate size-specific mass emission rates and particle characteristics for additional laser operational parameters in order to estimate occupational exposure, and to inform control strategies.

Investigation of Ultrafine Particle Emissions of Desktop 3D Printers in the Clean Room

It is getting more popular to use desktop 3D printers either at homes or offices, which may emit a large amount of particles when in use. This work aims to obtain accurate size-resolved particle emission rates from both single and two desktop 3D printers in a ten–thousand-level clean room, with acrylonitrile butadiene styrene (ABS) for the feedstock. Particle concentrations were measured at three different spots in the clean room. We found that the major size of particles produced by the 3D printers is less than 10μm (PM10). The further it is from the printer, the higher the particle concentrations are. Moreover, the smaller the size of particles, the higher the concentration of particles, with the size ranged from 0.25μm to 0.28μm corresponding to the highest concentration. The maximum value of particle concentration is around 2.5×104/L for single printer and 4×104/L for two printers.

Characterizing airborne fungal and bacterial concentrations and emission rates in six occupied children's classrooms.

Baseline information on size-resolved bacterial, fungal, and particulate matter (PM) indoor air concentrations and emission rates is presented for six school classrooms sampled in four countries. Human occupancy resulted in significantly elevated airborne bacterial (81 times on average), fungal (15 times), and PM mass (nine times) concentrations as compared to vacant conditions. Occupied indoor/outdoor (I/O) ratios consistently exceeded vacant I/O ratios. Regarding size distributions, average room-occupied bacterial, fungal, and PM geometric mean particle sizes were similar to one another while geometric means estimated for bacteria, fungi, and PM mass during vacant sampling were consistently lower than when occupied. Occupancy also resulted in elevated indoor bacterial-to-PM mass-based and number-based ratios above corresponding outdoor levels. Mean emission rates due to human occupancy were 14 million cells/person/h for bacteria, 14 million spore equivalents/person/h for fungi, and 22 mg/person/h for PM mass. Across all locations, indoor emissions contributed 83 ± 27% (bacteria), 66 ± 19% (fungi), and 83 ± 24% (PM mass) of the average indoor air concentrations during occupied times. An extensive data set of bacterial and fungal size-distributed indoor air concentrations and emission rates is presented. Analysis of these data contributes to an understanding of how indoor bacterial and fungal aerosols are influenced by human occupancy. This work extends beyond prior culture and DNA-based microbiome studies in buildings to include quantitative relationships between size-resolved bacterial and fungal concentrations in indoor air and building parameters such as occupancy, ventilation, and outdoor conditions. The work indicates that occupancy-associated emissions (e.g., via resuspension and shedding) contribute more to both bacterial and fungal indoor air concentrations than do outdoor sources for the occupied classrooms investigated in this study.

Particle number emission factors and volatile fraction of particles emitted from on-road gasoline direct injection passenger vehicles

Particle number emission factors, and the volatility of the particles, are measured on-road for five gasoline direct injection vehicles over a wide range of operating conditions including urban and highway driving conditions. Two condensation particle counters (CPC) were used to measure nascent and non-volatile (thermodenuded) particle concentrations for transient urban and highway tests. To measure the non-volatile concentration and also the volatility of the particles, a thermodenuder was employed to remove the semi-volatile material from the aerosol sample. Rapid accelerations were also studied in more detail by measuring the particle size distributions in real-time using a differential mobility spectrometer (DMS). The ratio of semi-volatile particles to total particle number is generally higher during acceleration followed by the idle operating mode. The number emission factors (for particles larger than 2.5 nm) ranged between 5.46 × 1011–3.50 × 1012/km for freshly emitted (nascent) particles and between 2.87 × 1011–3.31 × 1012/km for non-volatile (thermodenuded) particles. More particles per kilometer are produced during acceleration compared to cruise conditions where the non-volatile particle number emission factor for acceleration is 2.3 and 1.8 times higher than vehicle cruise for urban and highway driving cycles, respectively. Particle number emission factor models are also presented in terms of particle emission rate as a function of vehicle tractive power and also as a function of vehicle specific power as defined for the US Environmental Protection Agency's MOVES model.

Oxidatively damaged guanosine in white blood cells and in urine of welders: associations with exposure to welding fumes and body iron stores.

The International Agency for Research on Cancer considers the carcinogenicity of welding fume of priority for re-evaluation. Genotoxic effects in experimental animals are still inconclusive. Here, we investigated the association of personal exposure to metals in respirable welding fumes during a working shift with oxidatively damaged guanosine in DNA of white blood cells (WBC) and in postshift urine samples from 238 welders. Medians of 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodGuo) were 2.35/106 dGuo in DNA of WBC and 4.33 µg/g creatinine in urine. The median of 8-oxo-7,8-dihydroguanosine (8-oxoGuo) was 7.03 µg/g creatinine in urine. The extent of both urinary parameters was higher in welders applying techniques with high particle emission rates to stainless steel than in tungsten inert gas welders (8-oxodGuo: 9.96 vs. 4.49 µg/L, 8-oxoGuo: 15.7 vs. 7.7 µg/L), but this apparent difference diminished after creatinine adjustment. We applied random intercept models to estimate the influence of airborne and systemic exposure to metals on oxidatively damaged guanosine in WBC and urine together with covariates. We observed a highly significant nonlinear association of urinary 8-oxoGuo with serum ferritin (P < 0.0001) and higher 8-oxoGuo concentrations for respirable iron >1,000 µg/m3 compared to ≤57 µg/m3. Similar effects were found for manganese. Airborne chromium but not nickel was associated with all oxidatively modified guanosine measures, whereas urinary chromium as well as nickel showed associations with urinary modified guanosines. In summary, oxidatively damaged urinary guanosine was associated with airborne and systemic exposure to metals in welders and showed a strong relation to body iron stores.Electronic supplementary materialThe online version of this article (doi:10.1007/s00204-014-1319-2) contains supplementary material, which is available to authorized users.

Indoor Air Quality in a Real Operating Theatre under Effective Use Conditions

The aim of this study is to investigate the impact of surgical staff on the indoor air quality in a uni-directional ventilation Operating Theatre (OT). Experimental measurements of particles and microclimate were acquired at rest and in operational conditions. The real OT (operational) use was simulated by a sham hip arthroplasty. CFD simulations were carried out outlining the studied environment used for experimental measurement campaign. A standard k-ε closure scheme based on RANS equations was implemented to solve the velocity and pressure field using an eddy viscosity approach. Temperature and relative humidity distributions were also computed keeping into account sensible and latent heat sources inside the OT. An Euler-based approach was applied to solve the concentration fields of gaseous contaminant and small particles (up to 5 μm in diameter) in the indoor air. An innovative strategy is proposed to estimate, by an iterative comparison between experimental data and numerical results, the emission rate of particles (differentiated by diameters) released by the occupants to be considered as source terms in the numerical model. Compliance with literature evidence concerning thermal and velocity fields and CO2 concentration was confirmed. From our analyses, some IAQ indexes were deduced, allowing monitoring of the local and overall OT air quality level supplied by the ventilating system during real operational conditions. The highest values of microbial air contamination were recorded during surgical activity; nevertheless, results showed the suitability of the ventilation system in providing the expected air quality.