Indoor Air Quality-Application of Risk Assessment and Risk Management Models - Case Study Example

Indoor Air Quality-Application of Risk Assessment and Risk Management Models Introduction Risk assessment is defined as the “science based systematic evaluation of a risk factor like an agent, planned action or an existing condition” (ECA 2000). A broad evaluation of risk assessment which includes the social, economic and political factors also is called risk management ( Common Wealth of Australia 2002).Many models have been developed by various organizations for the risk assessment and risk management. Most widely used models are the one developed by National Academy of Science (NAS) (Kolluru1986) and the other by WHO (Go 1987). According to WHO (2006), indoor air pollution is the eighth major risk factor which contributes to around 2.7 percent of the diseases worldwide. Further, estimates show that the people living in developing nations, particularly women and children are more affected by indoor air pollution due to their reliance on bio fuels like coal, dung, wood etc (WHO 2006). Thus indoor air quality has been a major area of concern for scientists and policy makers in the recent years due to its implications for health and welfare. Hence, the risk assessment and risk management of indoor air quality deserve special attention. This report discusses the risk assessment and risk management of indoor quality using the NAS model. The NAS model consists of hazard assessment, exposure assessment, risk characterization and risk management (Common Wealth of Australia 2002).All these steps focusing on indoor air quality are discussed in detail in the following sections. 2. Hazard Assessment A hazard is defined as an agent’s ability to produce any harmful effect on environment or health. It is not same as risk but can be the factor that can be a source of risk or risk factor. Hazard assessment involves two steps .They are hazard identification and dose response assessment (Common Wealth of Australia 2002).In the hazard identification stage of indoor air quality , it is determined whether nor not particular agents of indoor air are harmful to health or environment. The hazard identification for indoor quality is done based on epidemiological, toxicological and occupational or indoor studies. Hazard identification describes qualitatively the capability of agents to produce harmful effects .It is based on indoor observations that may potentially create adverse impacts on health or environment (ECA 2000). After identifying the hazards, the next step is doze response assessment. This describes quantitatively the links between the agents and adverse effects. The dose assessment is done using chamber studies and time series epidemiological studies. Though the general dose assessment method can be used for indoor air quality also, there are some exceptions. In the case of indoor air quality, the general dose assessment method will not be appropriate if the pollutant is inadequate ventilation. This is because ventilation by itself is not a risk factor but is a part of solution for indoor air pollution .Inadequate ventilation is the risk factor(ECA 2000).Further though the data for epidemiological studies is available from animals and healthy workers, the data from children, allergic patients etc are not available in these studies. These data are essentially needed for the dose assessment in indoor air quality. WHO (2006) has identified the main indoor air pollutants as dampness and mould, inadequate ventilation, allergens from hose dust mites, allergens from pets, and use of solid fuels and kerosene. The study by WHO (2004) has shown strong association between the indoor air pollutants and respiratory problems in Mongolia. Estimates show that the exposure to smoke due to the use of solid fuels and kerosene has resulted in respiratory problems in children leading to death and chronic bronchitis as well as pregnancy related disorders in women in African regions and developing nations (WHO 2006). 3. Exposure Assessment At this stage, the various dimensions of the exposure to risk factor are determined .The dimensions include magnitude, frequency, duration, extent and character of exposures are determined (Common Wealth of Australia 2002).The exact population that is exposed to risk and the channels of exposure are also identified in this step. This is generally done using deterministic and probabilistic models (EAC 2000). In the case of indoor air quality this is the most difficult stage .The direct methods of exposure assessment cannot find the spatial variability in this case due to the spending of maximum time by most individuals in the same space. In the case of known sources of risk, exposure assessment is done using deterministic models. These models however, assume small uncertainty and well understood process. Further, they assume the population as homogeneous. These assumptions may not be true in reality always. For example, they cannot capture the variable effects of many pollutants like wind pressure, air pressure gradients around a house etc. In these cases, either probability models are used or the results using modeling is compared with actual data measured (ECA 2000). In addition to these there are some differences between indoor and outdoor air environments. These are that (1) while the indoor air temperatures are stable and constant the outdoor air temperatures are not so stable and (2) the systems of ventilation are constant and stationary for indoor airs compared to outdoor airs. Hence, the exposure assessment methods s for indoor air quality needs to consider all these. Another major difference is that the particular population for indoor air quality exposure assessment is not well defined. This is because all people irrespective of their age are exposed to indoor air pollution(ECA 2000).Further there are some special groups that have separate effects of indoor air pollution like children, allergic, elderly and women who should be specifically analyzed. The exposure assessment models for indoor air quality whether deterministic or probabilistic may not have taken into account all the above factors. Hence, these models need to be compared with some actual data measured to examine the robustness and sensitivity of the results(EAC 2000). In addition to all these, consultation with the appropriate community is needed to collect information on their perceptions about the various uncertainties and assumptions used for modeling. The local communities’ ideas on uncertainty and variability regarding the impacts of air pollution can be very valuable in the exposure assessment process .In addition their ideas can help in testing the validity of many assumptions used in exposure assessment modeling. Their ideas regarding the duration, frequency and extent of the exposure to air pollution as well as the exposure settings also needs to be collected(Common Wealth of Australia,2002). The estimates by WHO show that nearly 3 billion people in the world are exposed to the risks of indoor air pollution since they depend on bio fuels for cooking (WHO 2006). Further, the women depending on these fuels for cooking are fond to be exposed to diseases like bronchitis and pregnancy disorders than the women who se alternative sources like gas or electricity for cooking. These estimates show that since women keep their small babies with them most time, they are also exposed to the impacts of the indoor air pollution disproportionately than others. 4. Risk Characterization The next and last stage of risk assessment in the NAS model is the characterization of risk. It involves the data integration from the first two steps ie hazard assessment and exposure assessment, overall evaluation of risk assessment and communication of the risk results to the risk managers and to the people(Common Wealth of Australia 2002). This step needs comparison of the data collected at various stages to some accepted and well-defined standards. WHO (1999a) has developed some guidelines to measure the air quality both indoor and outdoor. These guidelines are defined in such a way that pollution of air below these levels do not contribute to major risk. In these guidelines WHO includes in the general population, susceptible group like children, allergic etc also to define the exposed population for indoor air pollution. However, the guidelines occupation specific conditions are not given in WHO guidelines. To some extent, the model results can be compared with these guidelines. However, WHO itself points out that these guidelines cannot be taken as exact standards since many additional factors need to be considered for developing exact standards. In addition to these standards are developed by National Health and Medical Research Council (NHMRC1996) for indoor air quality. While characterizing risk, many differences exist between indoor and outdoor air characteristics. Exposures to indoor air pollutants will have great differences between individuals and small differences within individuals than the outdoor air exposures. The main reasons for this are the higher variability of indoor airs and the maximum spending of same indoor space by most persons. Further, the exposure of special groups like small children, women and allergic persons need to be evaluated carefully while characterizing their risks. Even in same indoor space, there can be exposure to different risk factors These need to be evaluated carefully. In addition to these, the nature, causes and effects of various risks of indoor air pollution need to be communicated to people at this stage. The communication needs to be effective without any language problems so that the public will get clear and enough idea of the risk characteristics (ECA 2000, Common Wealth of Australia 2002). 5. Risk Management After risk assessment, the next stage is risk management according to the NAS model. This forms the basis of the documentation for decision-making .It broadly evaluates the results of risk assessment based on the scientific data and economic, political and social considerations. The broad evaluation involves separating and analyzing the details of the risk assessment again and then develops a policy to resist the risk. The decision taken to resist the risk needs to be informed to the public. It is an essential part of risk management. Since the decisions taken are based on the estimated risk, the communication to public can help to reduce any discrepancies between their perceptions on risk and estimated risk (Common Wealth of Australia 2002). This is particularly relevant in the case of indoor air management because majority decisions in this case are made by the occupants or the residents in the indoor space themselves. The experts or the policy makers can cover only a minor portion of the decisions. Hence, communication about the risk assessment and management needs to be effectively done with the occupants for indoor air management (ECA 2000). The experts and policy makers need to give timely and efficient information to the occupants regarding the use of other relevant methods to combat indoor air pollution. The success of the professionals lie in their ability to make the public understand the nature of indoor air pollution risks, their effects , the various methods ways to combat the risks and their technological feasibility. In the case of indoor air pollution, the solutions to combat the risks are identified as dependence on liquefied petroleum gas, electricity, biogas and solar power for cooking and other purposes instead of using solid fuels like coal, dung, wood etc (WHO 2002). Properly designed and maintained chimney stoves are identified as the other option for rural areas where only solid fuels are available. Many changes in the behavior of users like drying up fuel wood, keeping away the small children from smoke etc can reduce the health effects of exposure to increased smoke .The briefing by WHO considers reducing risk and improving health as the major aim of these measures. While adopting these measures, other factors like the costs of investing in health also need to be considered. To find out the investment that gives higher value for money, cost effective ratios can be calculated and then policy measures can be implemented for that investment. Based on the cost effective ratios calculated by WHO well designed chimney stoves are fond as the most cost effective intervention for African regions (WHO 2002). Further, well defined region specific studies assessing the impact of the interventionist measures to reduce smoke exposure on the health of women, children etc need to be developed .This is essential for making the public aware of the need for such measures. 6. Conclusion In this report, the risk assessment and risk management of indoor air quality is discussed with the help of NAS model. It is found that indoor air pollution is one of the major sources’ of diseases all over the world. There are many differences between outdoor air environment and indoor air environments. Hence, at each stages of risk assessment these differences need to be considered. At each stages of the risk assessment and risk management, communication with public is essential since majority decisions regarding indoor air management are taken by the occupants themselves. The professionals need to make the public aware of the effectiveness of various indoor air management technologies through communication and well defined region specific studies. In spite of the widespread usage of the NAS model, it has limitations also. The assumption of risk assessment and risk management totally separated may not be true in reality always. Further, NAS model is not always good in capturing the adversity of effects . References Commonwealth of Australia.2002.Environmental Health Risk Assessment: Guidelines for Assessing Human Health Risks from Environmental Hazards, Department of Health and Ageing and Health Council, Australia. ECA (European Collaborative Action on, "Urban Air, lndoor Environment and Human Exposure"), 2000 . Risk Assessment In Relation To lndoor Air Quality, Report No 22. EUR 19529 EN. Luxembourg: Office for Official Publications of the European Communities. Go, F.C. 1987, Environmental impact assessment: an analysis of the methodological and substantive issues affecting human health considerations, EIA Guidance Document, Monitoring and Assessment Research Centre & WHO. Kolluru R V.1996. 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