Jack M Wolfson | Harvard School of Public Health (original) (raw)
Papers by Jack M Wolfson
Journal of the Air Pollution Control Association, 1980
Aerosol Science and Technology, 1994
ABSTRACT
Aerosol Science and Technology, 1999
This paper presents an experimental investigation of the increase in pressure drop with particle ... more This paper presents an experimental investigation of the increase in pressure drop with particle loading in Nuclepore lters. The average increase in pressure drop per unit time and particle mass concentration was measured as a function of particle size, density, and hygroscopicity. Two different Nuclepore lter pore diameters were tested (2 and 5 m m, respectively) at lter face velocities ranging from 4 to 52 cm/s. Our results showed that the increase in the pressure drop with particle loading inversely proportional to the square root of particle speci c gravity and depends weakly on particle diameter (to the power of -0.2). Furthermore, the increase in the pressure drop with particle loading is proportional to the lter face velocity and inversely proportional to the cube of the pore diameter. Particle interception and impaction on the pore edges are the main deposition mechanisms that are responsible for raising the pressure drop over time across the lter, especiallyfor particles having Stokes numbers below 5. Particle deposition due to diffusion inside the pores is important for particles smaller than 0.2 m m. These observations agree well with previously published studies on particle deposition on the pore edges in Nuclepore lters. Our tests also showed a dramatic decrease in the pressure drop with loading for hygroscopic particles as the relative humidity increases from 10% to 50%. The pressure drop with loading decreases almost inversely proportional to the relative humidity for ammonium sulfate particles.
Atmospheric Environment (1967), 1988
An improved method for measuring strong acidity of atmospheric aerosols is presented. An ammonia ... more An improved method for measuring strong acidity of atmospheric aerosols is presented. An ammonia diffusion denuder was developed to prevent neutralization of the acidic aerosol samples. In addition, a new procedure for protecting samples during shipment and analysis was used. An increase in the sensitivity of the analysis was achieved by extraction of the aerosol sample in a small solution volume, 3 ml, of IO-" N HCIO,,, and the use of a microelectrode for pH determination. Finally, results from a nine-month study in St Louis, Missouri and Kingston, Tennessee are given. lYey word index: Acid aerosols, ammonia, ammonium bisulfate, ammonium sulfate, diffusion denuder, ietovicite, nitrogen oxides, ozone, sulfates, sulfuric acid, sulfur dioxide.
Inhal Toxicol, 2000
ABSTRACT
Atmospheric Environment (1967), 1989
Laboratory studies evaluated the performance of a combined gas and particle sampling instrument. ... more Laboratory studies evaluated the performance of a combined gas and particle sampling instrument. Results of these investigations indicated that the system had the ability to reliably sample atmospheric gases. The sampler consists of a glass inlet/impactor, two Na,CO,-coated annular denuders to collect gaseous SO,, HNO, and HNO,, a citric acid-coated annular denuder to trap NHs, and a filter pack to collect fine particles and artifact gases. The inlet walls may be extracted to measure the extent of gas deposition on the inlet surfaces. Inlet transmission efficiencies and denuder gas collection efficiencies indicated excellent performance under a wide range of simulated conditions. Laboratory experiments with SO,, HNO, and NH, at various concentrations and relative humidities (l&90%) indicated that the annular denuders achieve collection efficiencies near 100%. Tests to investigate the deposition of SO,, HNO, and NH, on the walls of the glass inlet showed a small loss (< 10%) of HNO, and NH,. No loss of SO2 on inlet walls was detected. By extracting the inlet walls the deposited HNO, and NH, can be recovered.
Atmospheric Environment. Part A. General Topics, 1992
ABSTRACT Existing methods of measuring atmospheric aerosol strong acidity adequately prevent neut... more ABSTRACT Existing methods of measuring atmospheric aerosol strong acidity adequately prevent neutralization of fine-particle acidity by removing course alkaline particles and gaseous ammonia from air samples. However, these techniques do not consider particle interactions on the collection medium; therefore, they may still underestimate the actual aerosol acidity. Assessment of acid neutralization due to such interactions is made possible using annular denuder technology in conjuction with a newly designed filter pack. The amount of sulfate-related acidity neutralized by the collected ammonium nitrate (and possibly ammonium chloride and organic acid ammonium salts) is determined. Laboratory data suggest that large fractions of sulfate-related aerosol acidity are neutralized by ammonium nitrate particles during collection on filter media. Field data from the Harvard Acid Aerosol Health Effects Study also suggest that ammonium nitrate and possibly other ammonium salts, such as ammonium chloride, neutralize collected acid aerosols. For low-acid aerosol concentrations, the correction factor is significant; whereas, for high-acid concentrations, correction is negligible.
Environmental Science & Technology, 2014
There is growing concern about the accuracy of trace elemental analysis of ambient particulate ma... more There is growing concern about the accuracy of trace elemental analysis of ambient particulate matter (PM) samples. This has become important because ambient PM concentrations have decreased over the years, and the lower filter loadings result in difficulties in accurate analysis. The performance of energy-dispersive X-ray reflectance spectrometry was evaluated at Harvard School of Public Health using several methodologies, including intercomparison between two other laboratories. In reanalysis of standard films as unknown samples following calibration, the HSPH ED XRF measurements represented good performance: 2% errors in precision and 4% errors in accuracy. Replicate analysis of ambient air filters with low PM 2.5 levels indicated that S, K, Fe, and Ca showed excellent reproducibility, most other quantifiable elements were below 15% error, and the elements with larger percent of flagged measurements had less in precision. Results from the interlaboratory comparison demonstrated that most quantifiable elements, except Na and Al, were quite comparable for the three laboratories. Na performance could be validated from the stoichiometry of Na to Cl of indoor PM 2.5 filter samples.
Journal of Aerosol Science, 1998
Journal of Aerosol Science, 1997
This paper presents the development and evaluation of a high-volume rectangular geometry conventi... more This paper presents the development and evaluation of a high-volume rectangular geometry conventional impactor. Operating with a preselective inlet that removes particles larger than 2.5 pm in aerodynamic size, the impactor has been designed to sample ambient fine particles in the accumulation mode range (0.1 i d, < 2.5 pm). Particles are accelerated in a rectangular nozzle, 0.032 cm wide and 28 cm long, and impact on a filter medium attached on a porous glass frit, which is soaked in mineral oil. The impactor operates at a flow rate of 1000 lmin-' with a total pressure drop of 30 kPa. The performance of the slit-nozzle impactor was validated in laboratory and field tests, Laboratory experiments conducted with monodisperse fluorescent PSL particles showed that the aerodynamic diameter of the 50% cutpoint of the impactor is approximately 0.09 pm. Laboratory and field intercomparisons between the high-volume slit impactor and the microorifice uniform deposit impactor (MOUDI) showed that particulate nitrate and sulfate concentrations obtained with the two samplers are in good agreement (within 10%). Finally, a comparison between the particulate nitrate concentrations obtained with high-volume impactor and the Harvard/EPA annular denuder system (HEADS) was conducted, using indoor air as the test aerosol. Results from this comparison indicated that losses of nitrate from the impactor are not substantial and range between 5 and 15%. Results from the laboratory and field tests suggest that the high-volume impactor presented in this study constitutes a major improvement in the field of high-volume fine particle sampling. c 1997
Journal of Aerosol Science, 1998
Environmental Science & Technology, 2006
A primary mechanistic hypothesis by which ambient air particles have a significant negative impac... more A primary mechanistic hypothesis by which ambient air particles have a significant negative impact on human health is via the induction of pulmonary inflammatory responses mediated through the generation of reactive oxygen species (ROS). Development of a biosensor for the assessment of particulate ROS activity would be a significant advance in air pollution monitoring. The objective of this study was to evaluate whether air particulates interact directly with protective enzymes involved in oxidative stress responses. We performed enzyme activity assays on four enzymes involved in oxidative stress responses (Cu/Zn superoxide dismutase, Mn superoxide dismutase, glutathione peroxidase, and glutathione reductase) in the presence of particles of varying toxicities and found distinctive inhibition patterns. On the basis of these findings, we suggest a strategy for an enzyme bioassay that could be used to assess the potential of particles to generate ROS-induced responses.
Environmental Science & Technology, 1993
Currently available annular denuder/filter pack technology has been extremely useful for atmosphe... more Currently available annular denuder/filter pack technology has been extremely useful for atmospheric studies but has a relatively high cost for both instrumentation and operation. We have developed an alternative system which maintains and improves operational features while being more compact. The main, novel feature of the proposed system is the denuder component, which has a large number of small hexagonal glass tubes sealed inside an outer glass tube. The new system has the following advantages: (1) both the initial cost and the labor required for processing are much less than those of the annular denuder; (2) a length of only 3.8 cm yields the same collection capability as a length of 21 cm for the annular denuder, allowing a much more durable system; (3) this length also allows the use of several more denuders for simultaneous collection of a greater variety of gases; and (4) this new system is more convenient for large-scale monitoring studies. This paper presents the results from the performance evaluation of the impactor/honeycomb denuder/filter pack system. The tests include the impactor size cutoff determination, the honeycomb denuder efficiency and capacity measurements, and measurement of losses of acidic and basic gases on the sampler inlet surfaces. 1992,26A, 987-995.
Environmental Health Perspectives, 1999
Twenty-four-hour samples of PM10 (mass of particles with aerodynamic diameter < or = 10 mi... more Twenty-four-hour samples of PM10 (mass of particles with aerodynamic diameter < or = 10 microm), PM2.5, (mass of particles with aerodynamic diameter < or = 2.5 microm), particle strong acidity (H+), sulfate (SO42-), nitrate (NO3-), ammonia (NH3), nitrous acid (HONO), and sulfur dioxide were collected inside and outside of 281 homes during winter and summer periods. Measurements were also conducted during summer periods at a regional site. A total of 58 homes of nonsmokers were sampled during the summer periods and 223 homes were sampled during the winter periods. Seventy-four of the homes sampled during the winter reported the use of a kerosene heater. All homes sampled in the summer were located in southwest Virginia. All but 20 homes sampled in the winter were also located in southwest Virginia; the remainder of the homes were located in Connecticut. For homes without tobacco combustion, the regional air monitoring site (Vinton, VA) appeared to provide a reasonable estimate of concentrations of PM2.5 and SO42- during summer months outside and inside homes within the region, even when a substantial number of the homes used air conditioning. Average indoor/outdoor ratios for PM2.5 and SO42- during the summer period were 1.03 +/- 0.71 and 0.74 +/- 0.53, respectively. The indoor/outdoor mean ratio for sulfate suggests that on average approximately 75% of the fine aerosol indoors during the summer is associated with outdoor sources. Kerosene heater use during the winter months, in the absence of tobacco combustion, results in substantial increases in indoor concentrations of PM2.5, SO42-, and possibly H+, as compared to homes without kerosene heaters. During their use, we estimated that kerosene heaters added, on average, approximately 40 microg/m3 of PM2.5 and 15 microg/m3 of SO42- to background residential levels of 18 and 2 microg/m3, respectively. Results from using sulfuric acid-doped Teflon (E.I. Du Pont de Nemours & Co., Wilmington, DE) filters in homes with kerosene heaters suggest that acid particle concentrations may be substantially higher than those measured because of acid neutralization by ammonia. During the summer and winter periods indoor concentrations of ammonia are an order of magnitude higher indoors than outdoors and appear to result in lower indoor acid particle concentrations. Nitrous acid levels are higher indoors than outdoors during both winter and summer and are substantially higher in homes with unvented combustion sources.
Journal of the Air Pollution Control Association, 1980
Aerosol Science and Technology, 1994
ABSTRACT
Aerosol Science and Technology, 1999
This paper presents an experimental investigation of the increase in pressure drop with particle ... more This paper presents an experimental investigation of the increase in pressure drop with particle loading in Nuclepore lters. The average increase in pressure drop per unit time and particle mass concentration was measured as a function of particle size, density, and hygroscopicity. Two different Nuclepore lter pore diameters were tested (2 and 5 m m, respectively) at lter face velocities ranging from 4 to 52 cm/s. Our results showed that the increase in the pressure drop with particle loading inversely proportional to the square root of particle speci c gravity and depends weakly on particle diameter (to the power of -0.2). Furthermore, the increase in the pressure drop with particle loading is proportional to the lter face velocity and inversely proportional to the cube of the pore diameter. Particle interception and impaction on the pore edges are the main deposition mechanisms that are responsible for raising the pressure drop over time across the lter, especiallyfor particles having Stokes numbers below 5. Particle deposition due to diffusion inside the pores is important for particles smaller than 0.2 m m. These observations agree well with previously published studies on particle deposition on the pore edges in Nuclepore lters. Our tests also showed a dramatic decrease in the pressure drop with loading for hygroscopic particles as the relative humidity increases from 10% to 50%. The pressure drop with loading decreases almost inversely proportional to the relative humidity for ammonium sulfate particles.
Atmospheric Environment (1967), 1988
An improved method for measuring strong acidity of atmospheric aerosols is presented. An ammonia ... more An improved method for measuring strong acidity of atmospheric aerosols is presented. An ammonia diffusion denuder was developed to prevent neutralization of the acidic aerosol samples. In addition, a new procedure for protecting samples during shipment and analysis was used. An increase in the sensitivity of the analysis was achieved by extraction of the aerosol sample in a small solution volume, 3 ml, of IO-" N HCIO,,, and the use of a microelectrode for pH determination. Finally, results from a nine-month study in St Louis, Missouri and Kingston, Tennessee are given. lYey word index: Acid aerosols, ammonia, ammonium bisulfate, ammonium sulfate, diffusion denuder, ietovicite, nitrogen oxides, ozone, sulfates, sulfuric acid, sulfur dioxide.
Inhal Toxicol, 2000
ABSTRACT
Atmospheric Environment (1967), 1989
Laboratory studies evaluated the performance of a combined gas and particle sampling instrument. ... more Laboratory studies evaluated the performance of a combined gas and particle sampling instrument. Results of these investigations indicated that the system had the ability to reliably sample atmospheric gases. The sampler consists of a glass inlet/impactor, two Na,CO,-coated annular denuders to collect gaseous SO,, HNO, and HNO,, a citric acid-coated annular denuder to trap NHs, and a filter pack to collect fine particles and artifact gases. The inlet walls may be extracted to measure the extent of gas deposition on the inlet surfaces. Inlet transmission efficiencies and denuder gas collection efficiencies indicated excellent performance under a wide range of simulated conditions. Laboratory experiments with SO,, HNO, and NH, at various concentrations and relative humidities (l&90%) indicated that the annular denuders achieve collection efficiencies near 100%. Tests to investigate the deposition of SO,, HNO, and NH, on the walls of the glass inlet showed a small loss (< 10%) of HNO, and NH,. No loss of SO2 on inlet walls was detected. By extracting the inlet walls the deposited HNO, and NH, can be recovered.
Atmospheric Environment. Part A. General Topics, 1992
ABSTRACT Existing methods of measuring atmospheric aerosol strong acidity adequately prevent neut... more ABSTRACT Existing methods of measuring atmospheric aerosol strong acidity adequately prevent neutralization of fine-particle acidity by removing course alkaline particles and gaseous ammonia from air samples. However, these techniques do not consider particle interactions on the collection medium; therefore, they may still underestimate the actual aerosol acidity. Assessment of acid neutralization due to such interactions is made possible using annular denuder technology in conjuction with a newly designed filter pack. The amount of sulfate-related acidity neutralized by the collected ammonium nitrate (and possibly ammonium chloride and organic acid ammonium salts) is determined. Laboratory data suggest that large fractions of sulfate-related aerosol acidity are neutralized by ammonium nitrate particles during collection on filter media. Field data from the Harvard Acid Aerosol Health Effects Study also suggest that ammonium nitrate and possibly other ammonium salts, such as ammonium chloride, neutralize collected acid aerosols. For low-acid aerosol concentrations, the correction factor is significant; whereas, for high-acid concentrations, correction is negligible.
Environmental Science & Technology, 2014
There is growing concern about the accuracy of trace elemental analysis of ambient particulate ma... more There is growing concern about the accuracy of trace elemental analysis of ambient particulate matter (PM) samples. This has become important because ambient PM concentrations have decreased over the years, and the lower filter loadings result in difficulties in accurate analysis. The performance of energy-dispersive X-ray reflectance spectrometry was evaluated at Harvard School of Public Health using several methodologies, including intercomparison between two other laboratories. In reanalysis of standard films as unknown samples following calibration, the HSPH ED XRF measurements represented good performance: 2% errors in precision and 4% errors in accuracy. Replicate analysis of ambient air filters with low PM 2.5 levels indicated that S, K, Fe, and Ca showed excellent reproducibility, most other quantifiable elements were below 15% error, and the elements with larger percent of flagged measurements had less in precision. Results from the interlaboratory comparison demonstrated that most quantifiable elements, except Na and Al, were quite comparable for the three laboratories. Na performance could be validated from the stoichiometry of Na to Cl of indoor PM 2.5 filter samples.
Journal of Aerosol Science, 1998
Journal of Aerosol Science, 1997
This paper presents the development and evaluation of a high-volume rectangular geometry conventi... more This paper presents the development and evaluation of a high-volume rectangular geometry conventional impactor. Operating with a preselective inlet that removes particles larger than 2.5 pm in aerodynamic size, the impactor has been designed to sample ambient fine particles in the accumulation mode range (0.1 i d, < 2.5 pm). Particles are accelerated in a rectangular nozzle, 0.032 cm wide and 28 cm long, and impact on a filter medium attached on a porous glass frit, which is soaked in mineral oil. The impactor operates at a flow rate of 1000 lmin-' with a total pressure drop of 30 kPa. The performance of the slit-nozzle impactor was validated in laboratory and field tests, Laboratory experiments conducted with monodisperse fluorescent PSL particles showed that the aerodynamic diameter of the 50% cutpoint of the impactor is approximately 0.09 pm. Laboratory and field intercomparisons between the high-volume slit impactor and the microorifice uniform deposit impactor (MOUDI) showed that particulate nitrate and sulfate concentrations obtained with the two samplers are in good agreement (within 10%). Finally, a comparison between the particulate nitrate concentrations obtained with high-volume impactor and the Harvard/EPA annular denuder system (HEADS) was conducted, using indoor air as the test aerosol. Results from this comparison indicated that losses of nitrate from the impactor are not substantial and range between 5 and 15%. Results from the laboratory and field tests suggest that the high-volume impactor presented in this study constitutes a major improvement in the field of high-volume fine particle sampling. c 1997
Journal of Aerosol Science, 1998
Environmental Science & Technology, 2006
A primary mechanistic hypothesis by which ambient air particles have a significant negative impac... more A primary mechanistic hypothesis by which ambient air particles have a significant negative impact on human health is via the induction of pulmonary inflammatory responses mediated through the generation of reactive oxygen species (ROS). Development of a biosensor for the assessment of particulate ROS activity would be a significant advance in air pollution monitoring. The objective of this study was to evaluate whether air particulates interact directly with protective enzymes involved in oxidative stress responses. We performed enzyme activity assays on four enzymes involved in oxidative stress responses (Cu/Zn superoxide dismutase, Mn superoxide dismutase, glutathione peroxidase, and glutathione reductase) in the presence of particles of varying toxicities and found distinctive inhibition patterns. On the basis of these findings, we suggest a strategy for an enzyme bioassay that could be used to assess the potential of particles to generate ROS-induced responses.
Environmental Science & Technology, 1993
Currently available annular denuder/filter pack technology has been extremely useful for atmosphe... more Currently available annular denuder/filter pack technology has been extremely useful for atmospheric studies but has a relatively high cost for both instrumentation and operation. We have developed an alternative system which maintains and improves operational features while being more compact. The main, novel feature of the proposed system is the denuder component, which has a large number of small hexagonal glass tubes sealed inside an outer glass tube. The new system has the following advantages: (1) both the initial cost and the labor required for processing are much less than those of the annular denuder; (2) a length of only 3.8 cm yields the same collection capability as a length of 21 cm for the annular denuder, allowing a much more durable system; (3) this length also allows the use of several more denuders for simultaneous collection of a greater variety of gases; and (4) this new system is more convenient for large-scale monitoring studies. This paper presents the results from the performance evaluation of the impactor/honeycomb denuder/filter pack system. The tests include the impactor size cutoff determination, the honeycomb denuder efficiency and capacity measurements, and measurement of losses of acidic and basic gases on the sampler inlet surfaces. 1992,26A, 987-995.
Environmental Health Perspectives, 1999
Twenty-four-hour samples of PM10 (mass of particles with aerodynamic diameter < or = 10 mi... more Twenty-four-hour samples of PM10 (mass of particles with aerodynamic diameter < or = 10 microm), PM2.5, (mass of particles with aerodynamic diameter < or = 2.5 microm), particle strong acidity (H+), sulfate (SO42-), nitrate (NO3-), ammonia (NH3), nitrous acid (HONO), and sulfur dioxide were collected inside and outside of 281 homes during winter and summer periods. Measurements were also conducted during summer periods at a regional site. A total of 58 homes of nonsmokers were sampled during the summer periods and 223 homes were sampled during the winter periods. Seventy-four of the homes sampled during the winter reported the use of a kerosene heater. All homes sampled in the summer were located in southwest Virginia. All but 20 homes sampled in the winter were also located in southwest Virginia; the remainder of the homes were located in Connecticut. For homes without tobacco combustion, the regional air monitoring site (Vinton, VA) appeared to provide a reasonable estimate of concentrations of PM2.5 and SO42- during summer months outside and inside homes within the region, even when a substantial number of the homes used air conditioning. Average indoor/outdoor ratios for PM2.5 and SO42- during the summer period were 1.03 +/- 0.71 and 0.74 +/- 0.53, respectively. The indoor/outdoor mean ratio for sulfate suggests that on average approximately 75% of the fine aerosol indoors during the summer is associated with outdoor sources. Kerosene heater use during the winter months, in the absence of tobacco combustion, results in substantial increases in indoor concentrations of PM2.5, SO42-, and possibly H+, as compared to homes without kerosene heaters. During their use, we estimated that kerosene heaters added, on average, approximately 40 microg/m3 of PM2.5 and 15 microg/m3 of SO42- to background residential levels of 18 and 2 microg/m3, respectively. Results from using sulfuric acid-doped Teflon (E.I. Du Pont de Nemours & Co., Wilmington, DE) filters in homes with kerosene heaters suggest that acid particle concentrations may be substantially higher than those measured because of acid neutralization by ammonia. During the summer and winter periods indoor concentrations of ammonia are an order of magnitude higher indoors than outdoors and appear to result in lower indoor acid particle concentrations. Nitrous acid levels are higher indoors than outdoors during both winter and summer and are substantially higher in homes with unvented combustion sources.