M.A. Byrne

Secondhand smoke exposure and risk following the Irish smoking ban: an assessment of salivary cotinine concentrations in hotel workers and air nicotine levels in bars.

Objective: To investigate whether the Irish smoking ban has had an impact on secondhand smoke (SHS) exposures for hospitality workers. Design, setting, and participants: Before and after the smoking ban a cohort of workers (n  =  35) from a sample of city hotels (n  =  15) were tested for saliva cotinine concentrations and completed questionnaires. Additionally, a random sample (n  =  20) of city centre bars stratified by size (range 400–5000 square feet), were tested for air nicotine concentrations using passive samplers before and after the ban. Main outcome measures: Salivary cotinine concentrations (ng/ml), duration of self reported exposures to secondhand smoke, air nicotine (μg/cubic metre). Results: Cotinine concentrations reduced by 69%, from 1.6 ng/ml to 0.5 ng/ml median (SD 1.29; p < 0.005). Overall 74% of subjects experienced decreases (range 16–99%), with 60% showing a halving of exposure levels at follow up. Self reported exposure to SHS at work showed a significant reduction from a median 30 hours a week to zero (p < 0.001). There was an 83% reduction in air nicotine concentrations from median 35.5 µg/m3 to 5.95 µg/m3 (p < 0.001). At baseline, three bars (16%) were below the 6.8 μg/m3 air nicotine significant risk level for lung cancer alone; at follow up this increased to 10 (53%). Conclusions: Passive smoking and associated risks were significantly reduced but not totally eliminated. Exposure to SHS is still possible for those working where smoking is still allowed and those working where smoke may migrate from outdoor areas. Further research is required to assess the true extent and magnitude of these exposures.

STABLE TRACER AEROSOL DEPOSITION MEASUREMENTS IN A TEST CHAMBER

Abstract In order to provide data for evaluating the exposure of domestic building occupants to particulate pollutants from a variety of sources it is necessary to carry out aerosol deposition experiments in real house environments. To complement such studies in real houses, in which many influences on aerosol deposition exist simultaneously, it is desirable to carry out aerosol deposition experiments in test chambers under controlled conditions. An aerosol test chamber, with the dimensions of a small room, is described. The chamber is fitted with air sampling ports so that aerosol deposition velocities can be inferred by monitoring tracer aerosol concentration decay. The use of neutron-activatable aerosol facilitates simultaneous surface sampling. This is not possible with conventional light-scattering aerosol detection techniques and thus provides valuable information on mass transport limited deposition. Aerosol deposition experiments have been carried out, under turbulent conditions using monodisperse neutron-activatable particles of four sizes. Results are compared with the theory of Corner and Pendlebury (1951, Proc. Phys. Soc. B64 , 645–654). Surface sampling has been used to obtain additional information from average aerosol deposition velocities. The potential of the test chamber as a means of assessing the influence of internal building surface character upon aerosol deposition velocity is illustrated.

Modelling of indoor exposure to nitrogen dioxide in the UK

A dynamic multi-compartment computer model has been developed to describe the physical processes determining indoor pollutant concentrations as a function of outdoor concentrations, indoor emission rates and building characteristics. The model has been parameterised for typical UK homes and workplaces and linked to a time-activity model to calculate exposures for a representative homemaker, schoolchild and o

Experimental Studies of the Effect of Rough Surfaces and Air Speed on Aerosol Deposition in a Test Chamber

ce worker, with respect to NO 2 . The estimates of population exposures, for selected urban and rural sites, are expressed in terms of annual means and frequency of hours in which air quality standards are exceeded. The annual mean exposures are estimated to fall within the range of 5}21 ppb for homes with no source, and 21}27 ppb for homes with gas cooking, varying across sites and population groups. The contribution of outdoor exposure to annual mean NO 2 exposure varied from 5 to 24%, that of indoor penetration of outdoor air from 17 to 86% and that of gas cooking from 0 to 78%. The frequency of exposure to 1 h mean concentrations above 150 ppb was very low, except for people cooking with gas. ( 2000 Elsevier Science Ltd. All rights reserved.

Scavenging of sub-micrometre aerosol particles by water drops

Understanding the fate of particles indoors is important for human health assessment because deposited particles, unless resuspended, cannot be inhaled. To complement studies in real buildings, where control of variables is often difficult, an experimental test chamber facility (8 m 3 ) was designed to study particle deposition under well-stirred conditions using monodisperse tracer aerosol particles in the range of 0.7 to 5.4 w m. The use of neutron-activatable tracers facilitated simultaneous surface sampling and aerosol concentration decay measurements. Aerosol deposition on both smooth surfaces and regular arrays of three-dimensional roughness elements under 3 different airflow speeds was investigated in the test chamber.It was expected that the texture of the chamber surface would significantly influence particle deposition, but some counterintuitive results were observed: under the lowest airflow condition and for the smallest particle size, particle deposition onto rough samples was found to be less than on the corresponding smooth surfaces. The ratio of particle deposition on rough surfaces relative to smooth surfaces increased with particle size and magnitude of airflow. For the largest particle size and airflow speed, particle deposition on the rough surfaces exceeded that on the smooth surfaces by a factor of 3.

AEROSOL DEPOSITION IN TURBULENT CHANNEL FLOW ON A REGULAR ARRAY OF THREE-DIMENSIONAL ROUGHNESS ELEMENTS

Experiments were carried out in order to measure the collection efficiencies, E, with which small-sized water drops (of radii between 400 and 500 μm) carrying electrical charge, Qa (from 5 × 10−14 to 2 × 10−11 C), collect monodisperse aerosol particles of radii between 0.35 and 0.88 μm. The measured values of collection efficiency were within the range 1–6% and were in good agreement with previous results. The measurement show an increase in E with increase in aerosol particle radius, drop radius and drop charge.

Averaging periods for indoor-outdoor ratios of pollution in naturally ventilated non-domestic buildings near a busy road

Abstract Understanding particle deposition onto rough surfaces is important for many engineering and environmental applications. An experimental system was designed for the study of aerosol deposition on regular arrays of uniform elements (in the form of discrete protrusions) in a turbulent ventilation duct flow using monodisperse tracer small particles, in the range 0.7– 7.1 μ m . The Reynolds number for the test conditions was 44,000 in the 150 mm square duct. The roughness elements were arranged at two different orientations with respect to the airflow direction and the aerosol deposition velocity and pressure drop were measured for both orientations. Compared to earlier measurements in the same duct system involving smooth or ribbed surfaces, a significant increase in deposition velocity onto the regular roughness elements is observed. In addition, the associated pressure loss penalty is lower than in the presence of the roughness elements than in the presence of the ribbed surfaces. This may be attributable to the small dimensionless roughness height of the elements, which results only in a moderate distortion of the flow structure near the surfaces.

Radiation dose implications of airborne contaminant deposition to humans

Abstract Continuous measurements of carbon monoxide (CO) and particulate matter (PM 10 , PM 2.5 and PM 1 ) were made inside and outside two naturally ventilated (NV) and two mechanically assisted (MV) spaces overlooking the same six-lane highway in Central London. The indoor/outdoor ( I / O ) ratio was calculated for each site for the whole monitoring period in the usual way, and then cumulatively at each hourly time-step from the start of monitoring up to the whole period in order to track the evolution of the I / O ratio with length of monitoring or averaging period. Hourly data were also sorted by wind speed and direction and I / O ratios calculated for each direction/speed set from ensemble means. I / O ratios for the whole period were generally lower in the NV spaces than the MV, however, the indoor–outdoor relationship in the NV spaces was found to vary substantially with wind direction. For a constant above-roof wind speed, I / O ratios of CO varied by 50–60% about the mean value with direction, and by 20–30% for particulate matter. Consequently, I / O ratios for NV spaces depended on the distribution of wind direction within the calculation period and, hence, on the length of monitoring period. The I / O ratio in one NV space changed by a factor of three between the early stages and final stages of monitoring, with a “stable” final value (±5%) achieved after 900 h of monitoring. By contrast, in the MV spaces under constant fan speed, constant values for the I / O ratio were achieved for CO within 4 h of the start of monitoring. It is argued here that field assessments of the filtration performance of naturally ventilated spaces need to consider exposure to and distribution of natural ventilation drivers within the monitoring period in order to draw meaningful comparisons for design and exposure assessment purposes.

Modelling the Contribution of Passive Smoking to Exposure to PM10 in UK Homes

Abstract— In nuclear accident consequence assessment, dose contributions from radionuclide deposition on the human body have in the past generally been either ignored or estimated on the basis of rather simple models. Recent experimental work has improved the state of knowledge of relevant processes and parameter ranges. The results presented in this paper represent a first approach to a detailed assessment of doses from radiopollutant deposition on the human body, based on contaminant-specific data. Both the dose to skin from beta-emitters and the whole-body dose from gamma-emitters on body surfaces were found to give potentially significant contributions to dose. Further, skin penetration of some contaminants could lead to significant internal doses.

Particle deposition in ventilation duct onto three-dimensional roughness elements

A physical compartmental model (INTAIR) has been pa rameterised to estimate PM10 concentrations and has been used to assess the contribution of smoking to PM10 levels for typical homes in the UK. The results suggest that smoking activity at home increases the daily mean concentrations in the living room by 1-1.5 μg.m-3 per cigarette smoked, and may contribute significantly to personal exposures to PM10. The model simulations demonstrate that the contribution of smoking to daily mean concentrations is highly dependent on the air exchange rate between the room and outdoors.