Is It Feasible to Construct a Community Profile of Exposure to Industrial Air
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542 Occup Environ Med 2000;57:542–549 Occup Environ Med: first published as 10.1136/oem.57.8.542 on 1 August 2000. Downloaded from Is it feasible to construct a community profile of exposure to industrial air pollution? Tanja Pless-Mulloli, Christine E Dunn, Raj Bhopal, Peter Phillimore, Suzanne MoVatt, John Edwards Abstract residents living close to industries a compre- Objective—An epidemiological investiga- hensive picture of past and contemporary tion to assess the validity of residential exposure is required. However, to characterise proximity to industry as a measure of air pollution and its variability in time and community exposure. space, necessitates reliance largely on data col- Methods—19 Housing estates in Teesside lected for diVerent purposes—for example, to (population 1991: 77 330) in north east fulfil statutory obligations. In the end, a judge- England were grouped into zones: A=near; ment has to be made on how far the chosen B=intermediate; C=further from industry. exposure measures are likely to reflect the With residential proximity of socioeco- exposure of the population. nomically matched populations as a start- Based on the study of detailed accounts of ing point a historical land use survey, the validity and reliability of exposure measure- historical air quality reports, air quality ments and a systematic analysis of diVerential monitoring, dispersion modelling data, misclassification of exposure,2–6 the criteria we and questionnaire data, were examined. used to make judgements on whether the Results—The populations in zones A, B, exposure surrogate residential proximity to and C were similar for socioeconomic industry was valid were: (a) Have we been able indicators and smoking history. Areas to characterise the temporal and spatial pattern currently closest to industry had also been of exposure in our study areas? (b)Havewe closest for most of the 20th century. been able to disentangle industrial sources Historical reports highlighted the influ- from other pollution sources? (c)HavediVer- ence of industrial emissions to local air ent methods of exposure assessment comple- quality, but it was diYcult to follow spatial mented one another to draw an overall picture? pollution patterns over time. Whereas (d) How much have the data shown about the contemporary NOx and benzene concen- true exposure of populations in the past? (e) trations showed no geographical varia- Department of Was the initial assumption and design based on Epidemiology and tion, dispersion modelling of emissions proximity of industry as a surrogate for (116 industrial stacks, traYc, and domes- Public Health, School residential exposure vindicated? http://oem.bmj.com/ of Health Sciences, tic sources) showed a gradient associated Often, polluting industries are located in University of with industry. The presumed exposure areas with poor populations,7–9 among whom Newcastle, gradient of areas by proximity to industry high smoking rates, poor housing conditions, Framlington Place, (A>B>C) was evident for all of zone A and Newcastle upon Tyne, and unemployment prevail. Because these NE2 4HH, UK most of zones B and C. socioeconomic characteristics are strong deter- T Pless-Mulloli Conclusions—It was feasible to assemble a minants of both exposures and ill health several R Bhopal picture of community exposure by inte- approaches have been developed to take them SMoVatt gration of measurements from diVerent into account at the design and analysis stage of on September 28, 2021 by guest. Protected copyright. sources. Proximity of residence was a rea- 8 10–18 Department of epidemiological studies. We chose socio- Geography, University sonable surrogate for complex community economically matched populations with the of Durham, Durham exposure. Townsend deprivation score and additional DH1 3LE, UK (Occup Environ Med 2000;57:542–549) census variables, therefore correcting for socio- C E Dunn Keywords: exposure assessment; community exposure; economic influences at the design stage. Department of Social industrial pollution In summary, there is currently no single Policy, University of method of assessment of exposure that could Newcastle, NE1 7RU, conceptually or indeed in practice be consid- UK In environmental epidemiology studies the ered as a gold standard. The question we con- P Phillimore assessment of exposure of a population re- sider in this paper is whether we can build up a useful picture of exposure of a community by Department of mains both an on going area of concern when Environmental Health, interpreting results and a major methodologi- combining data from various sources? We School of Medicine, cal challenge at the design stage. This is examined diVerent methods of assessing expo- Flinders University of especially the case for retrospective exposure sure supplementing data with evidence from South Australia, GPO assessment: gaps in the spatial and temporal surveys and descriptive accounts of past pollu- Box 2100, Adelaide coverage, the relative crudity of past measure- tion to create a picture of past and present 5001, Australia J Edwards ment techniques, and changes in techniques exposure covering more than 40 years. are among the many problems; and exposure The paper arises out of an epidemiological Correspondence to: assessment has therefore been earmarked as an study into the association between proximity of Dr Tanja-Pless-Mulloli area of future research.12 residence to an industrial complex and acute [email protected] To analyse the associations between expo- and chronic health outcomes.819It was evident Accepted 17 March 2000 sure to industrial air pollution and the health of at an early stage that due to resource and www.occenvmed.com Community profile of industrial air pollution 543 Occup Environ Med: first published as 10.1136/oem.57.8.542 on 1 August 2000. Downloaded from conceptual constraints, direct contemporary The epidemiological study was based on a measurements of exposure would be unable to comparison of areas matched for socioeco- capture the complex and varying exposures in a nomic characteristics. Neighbourhoods were community, let alone exposures in the past. grouped into near, intermediate, and further The study design was based, therefore, on from industry reflecting the hypothesised proximity of residence as a surrogate for expo- exposure gradient. The hypothesised exposure sure. It was then necessary to verify and gradient (A>B>C) was taking into account validate how good a surrogate of exposure the that concentrations of pollution were highest selected areas were. when no dispersion was taking place due to low wind speeds. The focus of this paper is what kind of picture of community exposure is it possible to create in disaggregated small neigh- Background bourhoods, and how far did this picture The research underpinning this paper was support the assumptions of residential proxim- driven by the hypothesis that populations living ity as a surrogate for exposure? close to industrial operations are likely to The identification of areas of varying proxim- experience greater pollution derived from the ity to industry involved a stepwise process to industry than those living further away. Previ- distinguish socially homogeneous localities.81517 ous research in the area had highlighted health Nineteen housing estates in Teesside (in 1991 diVerentials for all cause and respiratory the population was 77 330) were selected. The mortality under the age of 65 in populations other approaches for exposure assessment en- experiencing similar levels of socioeconomic 20–22 compassed a historical land use survey, air qual- deprivation, and diVerentials in exposure to ity monitoring including a review of historical air pollution were one of the possible explana- pollution data and local authority reports, tions. dispersion modelling, and a postal questionnaire Teesside is an industrial conurbation with a survey. population of over 400 000 (fig 1) character- ised by large petrochemical operations as well as steel and coke works, which have been con- Historical land use survey tinuous for 150 years. Chemicals and oil based A historical land use survey investigated the operations developed after 1920. Although possibility that the location of industrial devel- industry has tended to relocate down river, opments and closures aVected the exposure of moving away from residential populations, populations diVerently in the study zones. If in even in the 1980s and 1990s sizeable popula- the past, industries had existed in areas of the tions still lived close to industrial operations. study classified as intermediate or further from 490 510 530 550 570 590 245 Chemicals 235 http://oem.bmj.com/ 225 River Tees Coke ovens Chemicals 215 Chemicals and steel c a 205 1 on September 28, 2021 by guest. Protected copyright. 195 b 3 185 d 175 2 e 0 1 mile 0 1 kilometre N 165 155 Teesside Sunderland 480 450 470 490 510 530 Teesside 135 135 ZONE A, B, and C indicate varying proximity to industry ZONE A = near Built up areas Major roads outside study zones ZONE B = intermediate Industrial areas 1 Monitoring sites 1–3 ZONE C = further Open space a Monitoring sites a–e Figure 1 Housing estates in zones A, B, and C and selected monitoring sites for smoke and SO2. www.occenvmed.com 544 Pless-Mulloli, Dunn, Bhopal, et al Occup Environ Med: first published as 10.1136/oem.57.8.542 on 1 August 2000. Downloaded from Table 1 Land use within 500 m of study areas at four times Mandale (area 15, zone C), and Parkfields (area 16, zone C). Hemlington (area 14, zone Year C) had no housing until the late 1960s. Estate No Zone* Estate name 1900 1930 1960 1990 Overall, the land use survey confirmed the extent to which areas currently closest to 1 A Dormanstown O H XX XX industry had been close to industry earlier, 2 A Grangetown North XX XX XX XX 3 A Grangetown South O O H H indicating the appropriateness of areas in zone 4 A South Bank XX XX XX H A and few anomalies in our definition of zones 5 A Portrack and Tilery XX XX XX X 6 B Brambles Farm O O H H B and C.