Roy Harrison | University of Birmingham (original) (raw)

Papers by Roy Harrison

Research paper thumbnail of OC/EC ratio observations in Europe: Re-thinking the approach for apportionment between primary and secondary organic carbon

Atmospheric Environment, 2011

This study explores a large set of OC and EC measurements in PM 10 and PM 2.5 aerosol samples, un... more This study explores a large set of OC and EC measurements in PM 10 and PM 2.5 aerosol samples, undertaken with a long term constant analytical methodology, to evaluate the capability of the OC/EC minimum ratio to represent the ratio between the OC and EC aerosol components resulting from fossil fuel combustion (OC ff /EC ff ). The data set covers a wide geographical area in Europe, but with a particular focus upon Portugal, Spain and the United Kingdom, and includes a great variety of sites: urban (background, kerbside and tunnel), industrial, rural and remote. The highest minimum ratios were found in samples from remote and rural sites. Urban background sites have shown spatially and temporally consistent minimum ratios, of around 1.0 for PM 10 and 0.7 for PM 2.5 .The consistency of results has suggested that the method could be used as a tool to derive the ratio between OC and EC from fossil fuel combustion and consequently to differentiate OC from primary and secondary sources. To explore this capability, OC and EC measurements were performed in a busy roadway tunnel in central Lisbon. The OC/ EC ratio, which reflected the composition of vehicle combustion emissions, was in the range of 0.3e0.4. Ratios of OC/EC in roadside increment air (roadside minus urban background) in Birmingham, UK also lie within the range 0.3e0.4. Additional measurements were performed under heavy traffic conditions at two double kerbside sites located in the centre of Lisbon and Madrid. The OC/EC minimum ratios observed at both sites were found to be between those of the tunnel and those of urban background air, suggesting that minimum values commonly obtained for this parameter in open urban atmospheres over-predict the direct emissions of OC ff from road transport. Possible reasons for this discrepancy are explored.

Research paper thumbnail of Relationship of personal exposure to volatile organic compounds to home, work and fixed site outdoor concentrations

Science of The Total Environment, 2011

Personal exposures of 100 adult non-smokers living in the UK, as well as home and workplace micro... more Personal exposures of 100 adult non-smokers living in the UK, as well as home and workplace microenvironment concentrations of 15 volatile organic compounds were investigated. The strength of the association between personal exposure and indoor home and workplace concentrations as well as with central site ambient air concentrations in medium to low pollution areas was assessed. Home microenvironment concentrations were strongly associated with personal exposures indicating that the home is the driving factor determining personal exposures to VOCs, explaining between 11 and 75% of the total variability. Workplace and central site ambient concentrations were less correlated with the corresponding personal concentrations, explaining up to 11-22% of the variability only at the low exposure end of the concentration range (e.g. benzene concentrations b 2.5 μg m −3 ). One of the reasons for the discrepancies between personal exposures and central site data was that the latter does not account for exposure due to personal activities (e.g. commuting, painting). A moderate effect of season on the strength of the association between personal exposure and ambient concentrations was found. This needs to be taken into account when using fixed site measurements to infer exposures.

Research paper thumbnail of Source apportionment of atmospheric polycyclic aromatic hydrocarbons collected from an urban location in Birmingham, UK

Environ. Sci. Technol, Jan 1, 1996

... The aim of this work was to investigate a suite of inorganic pollutant and PAH concentrations... more ... The aim of this work was to investigate a suite of inorganic pollutant and PAH concentrations at an urban location and to use the combined data to conduct multivariate source apportionment for the Birmingham aerosol load and, thus, enable identification of major sources of air ...

Research paper thumbnail of Chemical associations of lead, cadmium, copper, and zinc in street dusts and roadside soils

Environmental Science & …, Jan 1, 1981

I 1249-58. 1975, i 4 , i3-8. (21) Haque, R.; Schmedding, D. W.; Freed, V. H. Enuiron. Sci. (22) L... more I 1249-58. 1975, i 4 , i3-8. (21) Haque, R.; Schmedding, D. W.; Freed, V. H. Enuiron. Sci. (22) Lawrence, J.; Tosine, H. M.

Research paper thumbnail of Particulate matter in the atmosphere: which particle properties are important for its effects on health?

The Science of the total environment, Jan 1, 2000

Whilst epidemiological studies have consistently demonstrated adverse effects of particulate matt... more Whilst epidemiological studies have consistently demonstrated adverse effects of particulate matter exposure on human health, the mechanism of effect is currently unclear. One of the major issues is whether the toxicity of the particles resides in some particular fraction of the particles as defined by chemical composition or size. This article reviews selected data on the major and minor component composition of PM2.5 and PM10 particulate matter showing quite major geographic variations in composition which are not reflected in the exposure-response coefficients determined from the epidemiology which show remarkably little spatial variation. The issue of particle size is more difficult to address due to the scarcity of data. Overall, the data presented provides little support for the idea that any single major or trace component of the particulate matter is responsible for the adverse effects. The issue of particle size is currently unclear and more research is warranted.

Research paper thumbnail of Pollution: causes, effects and control

Research paper thumbnail of Carbonaceous aerosol in urban and rural European atmospheres: estimation of secondary organic carbon concentrations

Atmospheric Environment, Jan 1, 1999

Aerosol samples from urban, rural and coastal areas in Europe were analysed for carbonaceous cont... more Aerosol samples from urban, rural and coastal areas in Europe were analysed for carbonaceous content by a thermaloptical transmission method. The fraction of particulate organic carbon with a secondary origin in gas/particle conversion of volatile organic ...

Research paper thumbnail of Toward direct measurement of atmospheric nucleation

Research paper thumbnail of Sources and processes affecting concentrations of PM10 and PM2. 5 particulate matter in Birmingham (UK)

Atmospheric …, Jan 1, 1997

Hourly average concentrations of PM 10 and PM 2.5 have been measured simultaneously at a site wit... more Hourly average concentrations of PM 10 and PM 2.5 have been measured simultaneously at a site within Birmingham UK between October 1994 and October 1995. Comparison of PM 10 and NO x data with two other sites in the same city shows comparable summer and winter ...

Research paper thumbnail of Cleaning methods for polythene containers prior to the determination of trace metals in fresh water samples

Analytical chemistry, Jan 1, 1981

Page 1. Anal. Chem. 1981, 53, 345-350 345 Table I. Ion Chromatographic Conditions eluant: flow ra... more Page 1. Anal. Chem. 1981, 53, 345-350 345 Table I. Ion Chromatographic Conditions eluant: flow rate: 138 mL/h (30%) separator column: 3 x 150 mm anion precolumn plus suppressor column: meter full scale: injection volume: 100 p L ...

Research paper thumbnail of Investigation of ultrafine particle formation during diesel exhaust dilution

Environmental science & technology, Jan 1, 1999

Measurements of the size distribution of particles emitted from a modern heavy duty diesel engine... more Measurements of the size distribution of particles emitted from a modern heavy duty diesel engine using fuel with a sulfur content of between 0.03 and 0.05% by mass have been made under constant engine operating conditions, but with variations in the humidity of dilution air and dilution ratio prior to particle size measurement. The results show clearly that the measured size distribution is crucially dependent upon the conditions of dilution, hence creating real difficulties for comparison of data between different investigators. Conditions of high dilution ratio and high relative humidity both tend to favor the production of nanoparticles, especially within the range below 50 nm diameter. Application of homogeneous nucleation theory shows that nanoparticle production during dilution is qualitatively consistent with the production of sulfuric acid, but the predicted nucleation rates are lower than those measured, in common with studies of nucleation in the atmosphere. Chemical analysis of size-fractionated particles shows enhancement of sulfate concentrations in humid dilution conditions and at high dilution ratios consistent with the above mechanism. The possible role of semivolatile organic compounds in these processes has not been investigated.

Research paper thumbnail of Concentrations and sources of VOCs in urban domestic and public microenvironments

Environmental science & …, Jan 1, 2001

Concentrations of 15 VOCs including 1,3-butadiene, benzene, and styrene were measured in a wide r... more Concentrations of 15 VOCs including 1,3-butadiene, benzene, and styrene were measured in a wide range of urban microenvironments, viz: homes, offices, restaurants, pubs, department stores, coach and train stations, cinemas, libraries, laboratories, perfume shops, heavily trafficked roadside locations, buses, trains, and automobiles. For most target VOCs-including 1,3-butadiene and benzene-mean concentrations at heavily trafficked roadside locations were exceeded by those in automobiles and were comparable to those in pubs and train stations. With regard to indoor-outdoor relationships in homes, this study revealed higher mean indoor concentrations, no correlation between simultaneously measured indoor and outdoor concentrations, and significantly different patterns of diurnal variation. Thus-in poorly ventilated buildings-indoor emission source strength is considered a more significant influence on VOC concentrations than infiltration of outdoor air. In the six smoking homes studied, environmental tobacco smoke (ETS) was found to make a substantial contribution to concentrations of 1,3-butadiene. This finding was based on the significantly higher concentrations detected in smoking compared to nonsmoking homes, the significant correlation between 1,3-butadiene concentrations and those of 3-ethenylpyridine (an ETS marker), factor analysis, and the results of a source apportionment exercise based on ratios of 1,3-butadiene to 3-ethenylpyridine.

Research paper thumbnail of Lead pollution: causes and control

Research paper thumbnail of Tropospheric cycle of nitrous acid

Journal of Geophysical Research, Jan 1, 1996

Measurements of the land surface exchange of nitrous acid over grass and sugar beet surfaces reve... more Measurements of the land surface exchange of nitrous acid over grass and sugar beet surfaces reveal both upward and downward fluxes with flux reversal occmTing at an ambient concentration of nitrogen dioxide of about 10 ppb. This confirms earlier preliminary findings and strengthens the hypothesis that substantial production of nitrous acid can occur on land surfaces from reaction of nitrogen dioxide and water vapor. Detailed measurements of nitrous acid have been made in central urban, suburban, and rural environments. These measurements, in conjunction with a simple box model, indicate that the atmospheric concentrations of nitrous acid are explicable in terms of a small number of basic processes in which the most important are the surface production of nitrous acid from nitrogen dioxide, atmospheric production from the NO-OH reaction and loss of nitrous acid by photolysis and dry deposition. In the suburban atmosphere, concentrations of nitrous acid are strongly correlated with nitrogen dioxide. In the rural atmosphere a different behavior is seen, with much higher nitrous acid to nitrogen dioxide ratios occurring in more polluted air with nitrogen dioxide concentrations in excess of 10 ppb. At lower nitrogen dioxide concentrations, net deposition of nitrous acid at the ground leads to very low concentrations in advected air. The model study indicates that during daytime in the suburban atmosphere, production of HONO from the NO-OH reaction can compete with photolysis giving a HONO concentration of a few tenths of a part per billion. At the highest observed daytime concentrations of HONO, production of OH radical from its photolysis can proceed at a rate more than 10 times faster than from photolysis of ozone.

Research paper thumbnail of Sources and concentration of nanoparticles (< 10 nm diameter) in the urban atmosphere

Atmospheric Environment, Jan 1, 2001

Whilst limited information on particle size distributions and number concentrations in cities is ... more Whilst limited information on particle size distributions and number concentrations in cities is available, very few data on the very smallest of particles, nanoparticles, have been recorded. Measurements in this study show that road tra$c and stationary combustion sources generate a signi"cant number of nanoparticles of diameter (10 nm. Measurements at the roadside (4 m from the kerb) and downwind from the tra$c (more than 25 m from the kerb) show that nanoparticles ( (10 nm diameter) accounted for more than 36}44% of the total particle number concentrations. Measurements designed to sample the plume of individual vehicles showed that both a diesel-and a petrol-fuelled vehicle generated nanoparticles ( (10 nm diameter). The fraction of nanoparticles was even greater in a plume 350 m downwind of a stationary combustion source. On a few occasions, a temporal association between nanoparticles in the size range 3}7 nm and solar radiation was observed in urban background air at times when no other local sources were in#uential, which suggests that homogeneous nucleation can also be an important source of particles in the urban atmosphere.

Research paper thumbnail of A European aerosol phenomenology--1: physical characteristics of particulate matter at kerbside, urban, rural and background sites in Europe

Atmospheric …, Jan 1, 2004

This paper synthesizes data on aerosol (particulate matter, PM) physical characteristics, which w... more This paper synthesizes data on aerosol (particulate matter, PM) physical characteristics, which were obtained in European aerosol research activities at free-troposphere, natural, rural, near-city, urban, and kerbside sites over the past decade. It covers only two sites in the semi-arid Mediterranean area, and lacks data from Eastern Europe. The data include PM10 and/or PM2.5 mass concentrations, and aerosol particle size distributions. Such data sets are more comprehensive than those currently provided by air quality monitoring networks (e.g. EMEP, EUROAIRNET). Data available from 31 sites in Europe (called ''The Network'') were reviewed. They were processed and plotted to allow comparisons in spite of differences in the sampling and analytical techniques used in various studies. A number of conclusions are drawn as follows:

Research paper thumbnail of Measurements of ultrafine particle concentration and size distribution in the urban atmosphere

The Science of the Total Environment, Jan 1, 1999

. Particle size distributions were measured at three adjacent sites in Birmingham: a busy roadsid... more . Particle size distributions were measured at three adjacent sites in Birmingham: a busy roadside A38 ; 30 m away Ž . from the road and a nearby urban background site. Two scanning mobility particle sizers SMPS , an electrical low Ž . pressure impactor ELPI , a condensation particle counter and a thermophoretic precipitator were employed to measure and collect particles. Excellent agreement on the number weighted size distribution was found between the SMPS and ELPI, as well as with sizes measured by transmission electron microscopy. The average number concentration at roadside measured on four separate days was between 1.6 and 1.9= 10 5 cm y3 with similar size distributions and more than half of measured particles smaller than 30 nm. Traffic was the main source of ultrafine particles at the roadside. A 24-h average of 2.68= 10 4 " 1.29= 10 4 cm y3 was measured, which is close to that in Ž Hughes et al. Physical and chemical characterization of atmospheric ultrafine particles in the Los Angeles area.

Research paper thumbnail of Measurements of the physical properties of particles in the urban atmosphere

Atmospheric Environment, Jan 1, 1999

... Operating two condensation nucleus counters in tandem to determine particles in the 3–7 nm si... more ... Operating two condensation nucleus counters in tandem to determine particles in the 3–7 nm size range by difference showed signficant numbers of particles in this range, apparently related to homogeneous nucleation processes. ...

Research paper thumbnail of Field measurements of the dissociation of ammonium nitrate and ammonium chloride aerosols

Atmospheric Environment (1967), Jan 1, 1989

Atmospheric ~n~n~at~ons of ifN03, HCl and NH3 have been measured at Essex, UK and Ckbauw, The ~et... more Atmospheric ~n~n~at~ons of ifN03, HCl and NH3 have been measured at Essex, UK and Ckbauw, The ~eth~la~ds, using botb iiiter pack (Essex) and denude1 ~~~uw) ssnxpbg methods and i~~~tjon times of 3, 12 and 24 h. ~om~risons of the ~~~nt~tion products [HNO,] PZis] and [HClj @JH,] with the predictions o~~uilib~urn chemical the~~yna~~ for a non-interactive external mixture of NH,CI and NH,NOs show generafly good agreement at tem~ratu~ above ca 5°C. and indicate that both aerosol salts are nobly present at these sites. The ratio [~~l]~NOs] agrees well with theory at lower temperatures (< -S'C), but shows a significant excess of HNO, at higher tem~rat~~. Reasons for deviations of measurements from theoretical predictions are discussed, although no firm conclusions are reached. Key word index: Ammonium nitrate, ammonium chloride, nitric acid, hydrochloric acid, ammonia, th~~~y~a~c ~ui~bri~m. Acknowledgement-On behalf of the Dutch measurements we are greatly indebted to Aart V&meuen, Willem Asman, Willem Muider and Elsbeth Pinksterboer, all former workers of the Institute for Meteorology and Oceanography of the University of U&e&t, for their support concexning the measurements and interpretation. Furthermore, special thanks are due to Anita Waijers-Upelaan and Sjaak Slanina of the Netherlands Energy Research Foundation, they took care of the analytical part of the measurements. 1598 A. Cl. ALLEN et al.

Research paper thumbnail of Characterization of particles from a current technology heavy-duty diesel engine

Environmental science & …, Jan 1, 2000

The physical properties, chemical properties, and morphology of particles from a current technolo... more The physical properties, chemical properties, and morphology of particles from a current technology diesel engine run under steady-state conditions were determined during five campaigns across three calendar years. Concentrations of particulate matter, NO x , HC, CO, and CO 2 ...

Research paper thumbnail of OC/EC ratio observations in Europe: Re-thinking the approach for apportionment between primary and secondary organic carbon

Atmospheric Environment, 2011

This study explores a large set of OC and EC measurements in PM 10 and PM 2.5 aerosol samples, un... more This study explores a large set of OC and EC measurements in PM 10 and PM 2.5 aerosol samples, undertaken with a long term constant analytical methodology, to evaluate the capability of the OC/EC minimum ratio to represent the ratio between the OC and EC aerosol components resulting from fossil fuel combustion (OC ff /EC ff ). The data set covers a wide geographical area in Europe, but with a particular focus upon Portugal, Spain and the United Kingdom, and includes a great variety of sites: urban (background, kerbside and tunnel), industrial, rural and remote. The highest minimum ratios were found in samples from remote and rural sites. Urban background sites have shown spatially and temporally consistent minimum ratios, of around 1.0 for PM 10 and 0.7 for PM 2.5 .The consistency of results has suggested that the method could be used as a tool to derive the ratio between OC and EC from fossil fuel combustion and consequently to differentiate OC from primary and secondary sources. To explore this capability, OC and EC measurements were performed in a busy roadway tunnel in central Lisbon. The OC/ EC ratio, which reflected the composition of vehicle combustion emissions, was in the range of 0.3e0.4. Ratios of OC/EC in roadside increment air (roadside minus urban background) in Birmingham, UK also lie within the range 0.3e0.4. Additional measurements were performed under heavy traffic conditions at two double kerbside sites located in the centre of Lisbon and Madrid. The OC/EC minimum ratios observed at both sites were found to be between those of the tunnel and those of urban background air, suggesting that minimum values commonly obtained for this parameter in open urban atmospheres over-predict the direct emissions of OC ff from road transport. Possible reasons for this discrepancy are explored.

Research paper thumbnail of Relationship of personal exposure to volatile organic compounds to home, work and fixed site outdoor concentrations

Science of The Total Environment, 2011

Personal exposures of 100 adult non-smokers living in the UK, as well as home and workplace micro... more Personal exposures of 100 adult non-smokers living in the UK, as well as home and workplace microenvironment concentrations of 15 volatile organic compounds were investigated. The strength of the association between personal exposure and indoor home and workplace concentrations as well as with central site ambient air concentrations in medium to low pollution areas was assessed. Home microenvironment concentrations were strongly associated with personal exposures indicating that the home is the driving factor determining personal exposures to VOCs, explaining between 11 and 75% of the total variability. Workplace and central site ambient concentrations were less correlated with the corresponding personal concentrations, explaining up to 11-22% of the variability only at the low exposure end of the concentration range (e.g. benzene concentrations b 2.5 μg m −3 ). One of the reasons for the discrepancies between personal exposures and central site data was that the latter does not account for exposure due to personal activities (e.g. commuting, painting). A moderate effect of season on the strength of the association between personal exposure and ambient concentrations was found. This needs to be taken into account when using fixed site measurements to infer exposures.

Research paper thumbnail of Source apportionment of atmospheric polycyclic aromatic hydrocarbons collected from an urban location in Birmingham, UK

Environ. Sci. Technol, Jan 1, 1996

... The aim of this work was to investigate a suite of inorganic pollutant and PAH concentrations... more ... The aim of this work was to investigate a suite of inorganic pollutant and PAH concentrations at an urban location and to use the combined data to conduct multivariate source apportionment for the Birmingham aerosol load and, thus, enable identification of major sources of air ...

Research paper thumbnail of Chemical associations of lead, cadmium, copper, and zinc in street dusts and roadside soils

Environmental Science & …, Jan 1, 1981

I 1249-58. 1975, i 4 , i3-8. (21) Haque, R.; Schmedding, D. W.; Freed, V. H. Enuiron. Sci. (22) L... more I 1249-58. 1975, i 4 , i3-8. (21) Haque, R.; Schmedding, D. W.; Freed, V. H. Enuiron. Sci. (22) Lawrence, J.; Tosine, H. M.

Research paper thumbnail of Particulate matter in the atmosphere: which particle properties are important for its effects on health?

The Science of the total environment, Jan 1, 2000

Whilst epidemiological studies have consistently demonstrated adverse effects of particulate matt... more Whilst epidemiological studies have consistently demonstrated adverse effects of particulate matter exposure on human health, the mechanism of effect is currently unclear. One of the major issues is whether the toxicity of the particles resides in some particular fraction of the particles as defined by chemical composition or size. This article reviews selected data on the major and minor component composition of PM2.5 and PM10 particulate matter showing quite major geographic variations in composition which are not reflected in the exposure-response coefficients determined from the epidemiology which show remarkably little spatial variation. The issue of particle size is more difficult to address due to the scarcity of data. Overall, the data presented provides little support for the idea that any single major or trace component of the particulate matter is responsible for the adverse effects. The issue of particle size is currently unclear and more research is warranted.

Research paper thumbnail of Pollution: causes, effects and control

Research paper thumbnail of Carbonaceous aerosol in urban and rural European atmospheres: estimation of secondary organic carbon concentrations

Atmospheric Environment, Jan 1, 1999

Aerosol samples from urban, rural and coastal areas in Europe were analysed for carbonaceous cont... more Aerosol samples from urban, rural and coastal areas in Europe were analysed for carbonaceous content by a thermaloptical transmission method. The fraction of particulate organic carbon with a secondary origin in gas/particle conversion of volatile organic ...

Research paper thumbnail of Toward direct measurement of atmospheric nucleation

Research paper thumbnail of Sources and processes affecting concentrations of PM10 and PM2. 5 particulate matter in Birmingham (UK)

Atmospheric …, Jan 1, 1997

Hourly average concentrations of PM 10 and PM 2.5 have been measured simultaneously at a site wit... more Hourly average concentrations of PM 10 and PM 2.5 have been measured simultaneously at a site within Birmingham UK between October 1994 and October 1995. Comparison of PM 10 and NO x data with two other sites in the same city shows comparable summer and winter ...

Research paper thumbnail of Cleaning methods for polythene containers prior to the determination of trace metals in fresh water samples

Analytical chemistry, Jan 1, 1981

Page 1. Anal. Chem. 1981, 53, 345-350 345 Table I. Ion Chromatographic Conditions eluant: flow ra... more Page 1. Anal. Chem. 1981, 53, 345-350 345 Table I. Ion Chromatographic Conditions eluant: flow rate: 138 mL/h (30%) separator column: 3 x 150 mm anion precolumn plus suppressor column: meter full scale: injection volume: 100 p L ...

Research paper thumbnail of Investigation of ultrafine particle formation during diesel exhaust dilution

Environmental science & technology, Jan 1, 1999

Measurements of the size distribution of particles emitted from a modern heavy duty diesel engine... more Measurements of the size distribution of particles emitted from a modern heavy duty diesel engine using fuel with a sulfur content of between 0.03 and 0.05% by mass have been made under constant engine operating conditions, but with variations in the humidity of dilution air and dilution ratio prior to particle size measurement. The results show clearly that the measured size distribution is crucially dependent upon the conditions of dilution, hence creating real difficulties for comparison of data between different investigators. Conditions of high dilution ratio and high relative humidity both tend to favor the production of nanoparticles, especially within the range below 50 nm diameter. Application of homogeneous nucleation theory shows that nanoparticle production during dilution is qualitatively consistent with the production of sulfuric acid, but the predicted nucleation rates are lower than those measured, in common with studies of nucleation in the atmosphere. Chemical analysis of size-fractionated particles shows enhancement of sulfate concentrations in humid dilution conditions and at high dilution ratios consistent with the above mechanism. The possible role of semivolatile organic compounds in these processes has not been investigated.

Research paper thumbnail of Concentrations and sources of VOCs in urban domestic and public microenvironments

Environmental science & …, Jan 1, 2001

Concentrations of 15 VOCs including 1,3-butadiene, benzene, and styrene were measured in a wide r... more Concentrations of 15 VOCs including 1,3-butadiene, benzene, and styrene were measured in a wide range of urban microenvironments, viz: homes, offices, restaurants, pubs, department stores, coach and train stations, cinemas, libraries, laboratories, perfume shops, heavily trafficked roadside locations, buses, trains, and automobiles. For most target VOCs-including 1,3-butadiene and benzene-mean concentrations at heavily trafficked roadside locations were exceeded by those in automobiles and were comparable to those in pubs and train stations. With regard to indoor-outdoor relationships in homes, this study revealed higher mean indoor concentrations, no correlation between simultaneously measured indoor and outdoor concentrations, and significantly different patterns of diurnal variation. Thus-in poorly ventilated buildings-indoor emission source strength is considered a more significant influence on VOC concentrations than infiltration of outdoor air. In the six smoking homes studied, environmental tobacco smoke (ETS) was found to make a substantial contribution to concentrations of 1,3-butadiene. This finding was based on the significantly higher concentrations detected in smoking compared to nonsmoking homes, the significant correlation between 1,3-butadiene concentrations and those of 3-ethenylpyridine (an ETS marker), factor analysis, and the results of a source apportionment exercise based on ratios of 1,3-butadiene to 3-ethenylpyridine.

Research paper thumbnail of Lead pollution: causes and control

Research paper thumbnail of Tropospheric cycle of nitrous acid

Journal of Geophysical Research, Jan 1, 1996

Measurements of the land surface exchange of nitrous acid over grass and sugar beet surfaces reve... more Measurements of the land surface exchange of nitrous acid over grass and sugar beet surfaces reveal both upward and downward fluxes with flux reversal occmTing at an ambient concentration of nitrogen dioxide of about 10 ppb. This confirms earlier preliminary findings and strengthens the hypothesis that substantial production of nitrous acid can occur on land surfaces from reaction of nitrogen dioxide and water vapor. Detailed measurements of nitrous acid have been made in central urban, suburban, and rural environments. These measurements, in conjunction with a simple box model, indicate that the atmospheric concentrations of nitrous acid are explicable in terms of a small number of basic processes in which the most important are the surface production of nitrous acid from nitrogen dioxide, atmospheric production from the NO-OH reaction and loss of nitrous acid by photolysis and dry deposition. In the suburban atmosphere, concentrations of nitrous acid are strongly correlated with nitrogen dioxide. In the rural atmosphere a different behavior is seen, with much higher nitrous acid to nitrogen dioxide ratios occurring in more polluted air with nitrogen dioxide concentrations in excess of 10 ppb. At lower nitrogen dioxide concentrations, net deposition of nitrous acid at the ground leads to very low concentrations in advected air. The model study indicates that during daytime in the suburban atmosphere, production of HONO from the NO-OH reaction can compete with photolysis giving a HONO concentration of a few tenths of a part per billion. At the highest observed daytime concentrations of HONO, production of OH radical from its photolysis can proceed at a rate more than 10 times faster than from photolysis of ozone.

Research paper thumbnail of Sources and concentration of nanoparticles (< 10 nm diameter) in the urban atmosphere

Atmospheric Environment, Jan 1, 2001

Whilst limited information on particle size distributions and number concentrations in cities is ... more Whilst limited information on particle size distributions and number concentrations in cities is available, very few data on the very smallest of particles, nanoparticles, have been recorded. Measurements in this study show that road tra$c and stationary combustion sources generate a signi"cant number of nanoparticles of diameter (10 nm. Measurements at the roadside (4 m from the kerb) and downwind from the tra$c (more than 25 m from the kerb) show that nanoparticles ( (10 nm diameter) accounted for more than 36}44% of the total particle number concentrations. Measurements designed to sample the plume of individual vehicles showed that both a diesel-and a petrol-fuelled vehicle generated nanoparticles ( (10 nm diameter). The fraction of nanoparticles was even greater in a plume 350 m downwind of a stationary combustion source. On a few occasions, a temporal association between nanoparticles in the size range 3}7 nm and solar radiation was observed in urban background air at times when no other local sources were in#uential, which suggests that homogeneous nucleation can also be an important source of particles in the urban atmosphere.

Research paper thumbnail of A European aerosol phenomenology--1: physical characteristics of particulate matter at kerbside, urban, rural and background sites in Europe

Atmospheric …, Jan 1, 2004

This paper synthesizes data on aerosol (particulate matter, PM) physical characteristics, which w... more This paper synthesizes data on aerosol (particulate matter, PM) physical characteristics, which were obtained in European aerosol research activities at free-troposphere, natural, rural, near-city, urban, and kerbside sites over the past decade. It covers only two sites in the semi-arid Mediterranean area, and lacks data from Eastern Europe. The data include PM10 and/or PM2.5 mass concentrations, and aerosol particle size distributions. Such data sets are more comprehensive than those currently provided by air quality monitoring networks (e.g. EMEP, EUROAIRNET). Data available from 31 sites in Europe (called ''The Network'') were reviewed. They were processed and plotted to allow comparisons in spite of differences in the sampling and analytical techniques used in various studies. A number of conclusions are drawn as follows:

Research paper thumbnail of Measurements of ultrafine particle concentration and size distribution in the urban atmosphere

The Science of the Total Environment, Jan 1, 1999

. Particle size distributions were measured at three adjacent sites in Birmingham: a busy roadsid... more . Particle size distributions were measured at three adjacent sites in Birmingham: a busy roadside A38 ; 30 m away Ž . from the road and a nearby urban background site. Two scanning mobility particle sizers SMPS , an electrical low Ž . pressure impactor ELPI , a condensation particle counter and a thermophoretic precipitator were employed to measure and collect particles. Excellent agreement on the number weighted size distribution was found between the SMPS and ELPI, as well as with sizes measured by transmission electron microscopy. The average number concentration at roadside measured on four separate days was between 1.6 and 1.9= 10 5 cm y3 with similar size distributions and more than half of measured particles smaller than 30 nm. Traffic was the main source of ultrafine particles at the roadside. A 24-h average of 2.68= 10 4 " 1.29= 10 4 cm y3 was measured, which is close to that in Ž Hughes et al. Physical and chemical characterization of atmospheric ultrafine particles in the Los Angeles area.

Research paper thumbnail of Measurements of the physical properties of particles in the urban atmosphere

Atmospheric Environment, Jan 1, 1999

... Operating two condensation nucleus counters in tandem to determine particles in the 3–7 nm si... more ... Operating two condensation nucleus counters in tandem to determine particles in the 3–7 nm size range by difference showed signficant numbers of particles in this range, apparently related to homogeneous nucleation processes. ...

Research paper thumbnail of Field measurements of the dissociation of ammonium nitrate and ammonium chloride aerosols

Atmospheric Environment (1967), Jan 1, 1989

Atmospheric ~n~n~at~ons of ifN03, HCl and NH3 have been measured at Essex, UK and Ckbauw, The ~et... more Atmospheric ~n~n~at~ons of ifN03, HCl and NH3 have been measured at Essex, UK and Ckbauw, The ~eth~la~ds, using botb iiiter pack (Essex) and denude1 ~~~uw) ssnxpbg methods and i~~~tjon times of 3, 12 and 24 h. ~om~risons of the ~~~nt~tion products [HNO,] PZis] and [HClj @JH,] with the predictions o~~uilib~urn chemical the~~yna~~ for a non-interactive external mixture of NH,CI and NH,NOs show generafly good agreement at tem~ratu~ above ca 5°C. and indicate that both aerosol salts are nobly present at these sites. The ratio [~~l]~NOs] agrees well with theory at lower temperatures (< -S'C), but shows a significant excess of HNO, at higher tem~rat~~. Reasons for deviations of measurements from theoretical predictions are discussed, although no firm conclusions are reached. Key word index: Ammonium nitrate, ammonium chloride, nitric acid, hydrochloric acid, ammonia, th~~~y~a~c ~ui~bri~m. Acknowledgement-On behalf of the Dutch measurements we are greatly indebted to Aart V&meuen, Willem Asman, Willem Muider and Elsbeth Pinksterboer, all former workers of the Institute for Meteorology and Oceanography of the University of U&e&t, for their support concexning the measurements and interpretation. Furthermore, special thanks are due to Anita Waijers-Upelaan and Sjaak Slanina of the Netherlands Energy Research Foundation, they took care of the analytical part of the measurements. 1598 A. Cl. ALLEN et al.

Research paper thumbnail of Characterization of particles from a current technology heavy-duty diesel engine

Environmental science & …, Jan 1, 2000

The physical properties, chemical properties, and morphology of particles from a current technolo... more The physical properties, chemical properties, and morphology of particles from a current technology diesel engine run under steady-state conditions were determined during five campaigns across three calendar years. Concentrations of particulate matter, NO x , HC, CO, and CO 2 ...