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Health dust monitoring at derlwyn opencast coal site
Abstracts
336
AEROSOL DEPOSITION ON INTERNAL BUILDING SURFACES: COMPARISON OF MODELLING AND MEASUREMENT
* Centre
M. A. Byrne,* A. J. H. Goddard,*
F. C. Lockwood+ and M. Nasrullah’
for Analytical
and t ThermoFluids College, SW7 2BX,
Research
in the Environment, Department, Imperial
Section, U.K.
Mechanical
Engineering
The occupants of buildings may be exposed to a variety of particulate pollutants which constitute a health hazard when airborne or when deposited on internal building surfaces. In order to make comprehensive exposure assessments, which includes not only the inhalation route, but also ingestion and dermal transfer, it is necessary to complement aerosol concentration decay rate measurements with aerosol deposition rate data for individual internal building surfaces. A sensitive aerosol labelling and detection technique allows the analysis of aerosol particle-bearing surfaces; the use of neutron activatable aerosol at Imperial College for the measurement of aerosol deposition rates to individual surfaces has been previously discussed. In this paper, the use of the experimental results as validation data for an efficient computational model, developed at Imperial College, is discussed. The model simulates the movement of aerosol particles in a turbulent air-stream and considers both the particle and gas interactions with the turbulence in the bulk flow of the enclosure as well as the detailed particle interaction with the enclosure’s walls. The application of the model to the prediction of the proportion of aerosol particle mass deposited on each individual internal surface of the Imperial College test chamber, under stirred conditions, is described; predictions for a range of monodisperse particle sizes are presented and are compared with the experimental data.
HEALTH
DUST MONITORING
AT DERLWYN
OPENCAST
COAL SITE
A. M. King IMCL,
Burton-on
Trent,
DE15
OQD,
U.K.
A debate has continued for a number of years, over the possibility of links between airborne dust from opencast working and an adverse effect on the health of the local population. More recently, the debate has widened, to include other causes of ill-health within the urban environment. Concentrations of airborne particulate matter (dust) have been assessed near the boundary of Derlwyn Opencast Coal Site since September 1990, and are continuing. Measurements have been made within various health fractions, and using a variety of instruments. Respirable dust levels have been assessed throughout the period, using OSIRIS (optical) monitors. Samples of dust from the respirable, thoracic and inhalable fractions were collected on filters, in a comprehensive series of trials, over a 33 month period. A TEOM (PM,,) continuous monitor has been permanently positioned at the site since September 1993. Results from the comprehensive series of measurements, plus more recent data from the continuous monitors, are presented and discussed. The technique of “Pollution Profiling” is applied to simultaneously monitored dust and meteorological data. The contribution from site-generated dust is isolated from that carried in the ambient atmosphere. The principal conclusion drawn is that ambient dust levels predominate at all times. This is important not only to operations at all opencast coal sites, but is relevant to a better understanding of ambient levels of particulate matter throughout the U.K., and the operation of Air Quality Standards and controls.
FACTORS
AFFECTING
RESUSPENSION
FROM WET GRASS
M. J. J. Crook, M. J. Minski, A. J. H. Goddard and R. Kinnersley Imperial
College
of Science, Technology and Medicine, Centre for Analytical Research (C.A.R.E.), Silwood Park, Ascot, Berkshire, SL5 7TE, U.K.
in the Environment
Following nuclear accidents high concentrations of particulate material can be released into the environment. This material can become deposited onto surfaces many miles away by the processes of wet and dry deposition. If these surfaces are disturbed by physical or mechanical means the deposits can be resuspended into the atmosphere. Human exposure may result from inhalation and it is important that it can be predicted allowing dose rates to be estimated. Thirty-six experiments have been conducted using monodisperse, dysprosium labelled silica particles of three sizes (5, 10 and 20 pm) deposited onto perennial rye grass (Lolium perenne). Following deposition the canopy was sprayed with water and resuspension quantified. In a second series of experiments deposition was carried out in a Faraday cage reducing particle charge to a minimum. The samples generated were analysed using Instrumental Neutron Activation Analysis following irradiation in the Imperial College Reactor.
336
AEROSOL DEPOSITION ON INTERNAL BUILDING SURFACES: COMPARISON OF MODELLING AND MEASUREMENT
* Centre
M. A. Byrne,* A. J. H. Goddard,*
F. C. Lockwood+ and M. Nasrullah’
for Analytical
and t ThermoFluids College, SW7 2BX,
Research
in the Environment, Department, Imperial
Section, U.K.
Mechanical
Engineering
The occupants of buildings may be exposed to a variety of particulate pollutants which constitute a health hazard when airborne or when deposited on internal building surfaces. In order to make comprehensive exposure assessments, which includes not only the inhalation route, but also ingestion and dermal transfer, it is necessary to complement aerosol concentration decay rate measurements with aerosol deposition rate data for individual internal building surfaces. A sensitive aerosol labelling and detection technique allows the analysis of aerosol particle-bearing surfaces; the use of neutron activatable aerosol at Imperial College for the measurement of aerosol deposition rates to individual surfaces has been previously discussed. In this paper, the use of the experimental results as validation data for an efficient computational model, developed at Imperial College, is discussed. The model simulates the movement of aerosol particles in a turbulent air-stream and considers both the particle and gas interactions with the turbulence in the bulk flow of the enclosure as well as the detailed particle interaction with the enclosure’s walls. The application of the model to the prediction of the proportion of aerosol particle mass deposited on each individual internal surface of the Imperial College test chamber, under stirred conditions, is described; predictions for a range of monodisperse particle sizes are presented and are compared with the experimental data.
HEALTH
DUST MONITORING
AT DERLWYN
OPENCAST
COAL SITE
A. M. King IMCL,
Burton-on
Trent,
DE15
OQD,
U.K.
A debate has continued for a number of years, over the possibility of links between airborne dust from opencast working and an adverse effect on the health of the local population. More recently, the debate has widened, to include other causes of ill-health within the urban environment. Concentrations of airborne particulate matter (dust) have been assessed near the boundary of Derlwyn Opencast Coal Site since September 1990, and are continuing. Measurements have been made within various health fractions, and using a variety of instruments. Respirable dust levels have been assessed throughout the period, using OSIRIS (optical) monitors. Samples of dust from the respirable, thoracic and inhalable fractions were collected on filters, in a comprehensive series of trials, over a 33 month period. A TEOM (PM,,) continuous monitor has been permanently positioned at the site since September 1993. Results from the comprehensive series of measurements, plus more recent data from the continuous monitors, are presented and discussed. The technique of “Pollution Profiling” is applied to simultaneously monitored dust and meteorological data. The contribution from site-generated dust is isolated from that carried in the ambient atmosphere. The principal conclusion drawn is that ambient dust levels predominate at all times. This is important not only to operations at all opencast coal sites, but is relevant to a better understanding of ambient levels of particulate matter throughout the U.K., and the operation of Air Quality Standards and controls.
FACTORS
AFFECTING
RESUSPENSION
FROM WET GRASS
M. J. J. Crook, M. J. Minski, A. J. H. Goddard and R. Kinnersley Imperial
College
of Science, Technology and Medicine, Centre for Analytical Research (C.A.R.E.), Silwood Park, Ascot, Berkshire, SL5 7TE, U.K.
in the Environment
Following nuclear accidents high concentrations of particulate material can be released into the environment. This material can become deposited onto surfaces many miles away by the processes of wet and dry deposition. If these surfaces are disturbed by physical or mechanical means the deposits can be resuspended into the atmosphere. Human exposure may result from inhalation and it is important that it can be predicted allowing dose rates to be estimated. Thirty-six experiments have been conducted using monodisperse, dysprosium labelled silica particles of three sizes (5, 10 and 20 pm) deposited onto perennial rye grass (Lolium perenne). Following deposition the canopy was sprayed with water and resuspension quantified. In a second series of experiments deposition was carried out in a Faraday cage reducing particle charge to a minimum. The samples generated were analysed using Instrumental Neutron Activation Analysis following irradiation in the Imperial College Reactor.