The Role of Risk Assessment in Environmental Security - Research Paper Example

Introduction Exposure to air pollution may cause serious adverse health effects where symptoms from this exposure may range from respiratory illnesses that are noncritical to cancer or even premature death. Exposure to air pollution similarly does not affect every subpopulation. The groups at risk for reactions that are more severe include those that have preexisting respiratory diseases like asthmatics or emphysemas. Pregnant women, children, and the elderly are also sensitive populations to consider. Traffic-related air pollution remains to be a major contributor to air quality that is unhealthy, especially in urban areas with high traffic volume. Within these urban areas, the main source of the local variability concerning air pollution levels is traffic, with the largest concentrations and the risk of exposure to the air pollution occurring near the roads. Emissions from motor vehicles represent the complex criteria of air pollutants including nitrogen oxides, carbon monoxide, and particulate matter including hydrocarbons that react with nitrogen oxides and sunlight leading to formation of ground-level ozone. Individually, each pollutant is a suspected or well-known cause of adverse health effects. Also, a mixture of traffic-related pollutants can be difficult when measuring or modeling. For this reason, several epidemiologic studies depend on traffic measures. Studies may include, proximity to major roads, traffic density that has accumulated within a buffer, and traffic density that is on the nearest road. These measures are substitutes of exposure and account for traffic volume (e.g. number of vehicles per day). The measures are markers of concentration of emissions from the vehicle and type of emission. These measures also account for the distance that addresses air pollution gradients near the road. Traffic emissions are greatest at a point of release and they typically reduce near background levels which are within a range of 150 to 300 meters of a major roadway. Literature review In U.S.A., a minority and economically disadvantaged population share a highly disproportionate burden of contact with air pollution and risk. There is evidence that demonstrates that citizens with low socioeconomic status and the minority populations experience a greater residential exposure to traffic generated air pollution. This exposure is less for a population of nonminority and greater socioeconomic status. The estimated percentage of total population in U.S.A. with people staying within a range of 100 meters to 150 meters from a major highway is 4%. Kebbede (2004) suggested that, an increased traffic-related exposure to air pollution results in an increased risk of adverse health outcomes especially asthma. The percentage of a population exposed to air traffic-related pollution is rather larger in urban areas due to more roads, higher population density, and higher traffic volume. Gurney (1998) stated that, demographic and social disparities exist in relation to residential proximity to main highway roads. Larger disparities are viewed more as indicators of the minority status for instance race or ethnicity, language spoken at residential homes and nativity, than for indicators of socioeconomic status like educational attainment and poverty. Environmental justice literature provides evidence that, a socially disadvantaged population may experience a phenomenon referred to as triple tragedy. Gurney (1998) noted that, first, the minority, and poor groups suffer adverse health effects from behavioral and social determinants of health like psychosocial stress, poor nutrition and inadequate access to hospitals. Second, certain populations like people who speak a language other than English at home and people minority communities might be at a greater danger for exposure to air pollution due to residential proximity to main highways. Third, there is an interaction between these two factors, which implies that underprivileged groups undergo disproportionately greater negative health outcomes from air pollution exposure. Asthma is a chronic condition used when taking into account environmental justice and inequality issues associated with adverse effects of health from traffic-related pollution from major highways. According to studies conducted by Gustavsson (2008), asthma is an increasingly growing problem among the overall population in U.S.A. Prevalence of asthma among the U.S. population has increased by 75% since 2004. Motor vehicle pollution An exhaust of a motor vehicle is a major source of air pollution. The most widely known pollutants from a vehicle exhaust include sulfur and oxides, carbon monoxide, particulate matter, polycyclic aromatic hydrocarbons and unburned hydrocarbons from crankcase and fuel. Gurney (1998), further noted that, while the transformation and transport of these pollutants, particularly in places where both human exposure and pollutant concentrations are elevated has gained much attention while minimal attention focuses on measuring the exposures and pollutants near the heavily trafficked highways. In reference to Gustavsson (2008), a variety of evidence today suggests that a steep gradient of some pollutants exist near highways that are heavily travelled and that living around these increased pollution zones may cause detrimental effects of health. It is thus important to note that, heterogeneity of amounts and types of vehicles using highways may be significant. The typical fleet of vehicles in America comprises of sports utility vehicles, motorcycles, vans, buses, trucks and passenger cars. The size and composition of this fleet on any given highway can vary depending on day of week, use restrictions, and time of day for various classes of vehicles. These are but a few factors that will influence amounts and kinds of pollutants from tailpipe emissions. Recent interest has focused on investigating different composition of substances in polluted air whilst assessing toxicity. In reference to American Thoracic Society and American Lung Association (1994), the mechanisms via which air pollution produces adverse health effects related to asthma, involve a study that links air pollutants with methylation of a gene associated with asthma. The asthma pathway comprises of a variety of genes, coding for proteins associated with asthmatic responses. Increased exposure to substances in polluted air is greatly associated with the hypermethylation of Foxp3 locus, which is a regulatory T cell with impaired function in people with asthma. Sulfate and black carbon particles are highly associated with methylation of this gene in asthmatic patients. Asthma and major highway exposures Asthma is a disorder that involves airflow limitation and variable airway inflammation in response to a variety of triggers. Whereas most asthmatic children achieve better symptom control with minimal doses of corticosteroids, some remain asymptomatic despite treatment with larger doses of both inhaled and oral corticosteroids. These children with more severe inhaled corticosteroid refractory asthma use large proportion of healthcare related resources and end up suffering extreme morbidity. Previous studies conducted by American Thoracic Society and American Lung Association (1994), have found associations between development of the asthma symptoms in preschoolers and infants and traffic-related air pollutants. In addition to this there is a possibility of acquiring current asthma in schoolchildren. Recent studies have shown an increase in respiratory symptoms in children with asthma residing in a close proximity to major roads, associated with amount of emissions from tailpipes of vehicles. Asthma is strongly associated with housing proximity to major highways. The associates are strongest for children with no parental history of asthma and those who have lived in the same address before in life. Under this group, a much higher risk occurs near major roads and it diminishes to background rates with a range of 150 meters to 200 meters from main roads. According to studies conducted by American Thoracic Society and American Lung Association (1994), greater risks of asthma in association with long-term housing within a distance of 75 meters from main roads, are common among girls than boys. Moreover, according to National Research Council (1998), children highly endangered with incident asthma associated with exercises in high-ozone environments may not have any parental history of the asthma. A relationship between traffic-related exposures and asthma is biologically plausible, since particulate matter has indicated eliciting of responses relevant to pathogenesis of asthma for people living near major highways. Studies that monitor air pollution on the scale orders of magnitudes not less than near highway gradients, have discovered associations between prevalence of asthma and traffic generated pollution. A study in Miami area measured NOX, PM2.5, and BC over several weeks near schools and found both increased levels of pollution downwind from main roads and a linear relationship between black carbon and asthma among long-term residents. Homes of about 207 children produced measurement results of nitrogen oxide as an odds ratio of 1.83for outdoor nitrogen oxide and the lifetime diagnosis of the asthma. In reference to Morel (2006), the study also found similar association with a similar distance from a residence to freeway. This study suggests that monitoring of air at residential homes increases a statistical power for detecting asthma that is associated with highway exposures. Modeling of elemental carbon from traffic near major roads, based on monitored ambient air of PM2.5 has emerged as an important approach. Studies using this method have found an important association of traffic generated pollution with infant wheezing. In addition, the modeled values are better predictors than housing proximity to main roads. Studies conducted Recent cohort and case-control studies have found an increased risk associated with asthma during exposure of traffic-related pollutants to local residents. This study also indicated strong associations regarding lifetime asthma with the residential air containing nitrogen oxide, which is an indicator of variability of traffic associated pollutants. The measured nitrogen oxide was then moderately correlated with the total traffic-modeled pollution (i.e. R=0.59). In this prospective study, children from a variety of Miami communities have significant associations between measured outdoor exposure to NO2 and incident asthma. Krzyzanowski and Kuna-Dibbert (2005) stated that, this study analyses individually measured exposures to pollutants to assess incidence asthma. Parsimonious models controlling sex and age at the baseline hazard show that, relative humidity, medical insurance and Hispanic ethnicity are confounders in the models with NO2. Krzyzanowskiand Kuna-Dibbert (2005) noted that, air pollution exposures accounts for the larger portions of residual variance in community random effects than individual-level variables associated as confounders. The findings for residential NO2 are a sensitive inclusion of relative humidity variable. In Jacksonville, NO2 is a specific causal agent but also it represents a mixture of regional pollutants, traffic generated air pollution and photochemical products in the region. New cohort studies have found association of asthma exposure to non-freeway traffic models. This reflects some differences within distribution of main roads and freeways around residential homes in different studies. However, according to National Research Council (1998), these associations are consistent with proximity to major roads. This is due to few children living within a distance of 75 meters from a freeway. Residential distance to major roads is easier to estimate and compute from readily available data than the traffic volume and meteorological data needed to model an exposure. According to Morris (1948), these results are consistent to various European studies, which found an increased risk of asthma in children due to the high rate of traffic counts that are in proximity to homes. A study conducted in Britain that focused on a traffic range of 150 meters to children homes found a gradient of risk that was elevated markedly with decreasing home distance to major roadways. A recent case study conducted by Geographical Information Systems Software Company in Orlando found an association between childhood asthma and measured traffic-related pollutants near schools. However, in other areas in this state, studies based on the records of Medicaid covered children, concluded that, there was no association between traffic counts and asthma in a distance of 168 meters from their residences. Most of the inconsistencies of this literature are due to failure of several cohorts on asthma to account for patterns of efficient modification by age, duration, and parental history of housing proximity to major roads. Moreover, according to studies conducted by Morris (1948), adverse health effects of traffic-related pollutants in girls are greater as observed in previous cohorts on asthma and its related symptoms. Traffic-related asthma in Florida In the year 2012, approximately 20.5% of school students from public schools near major roads had lifetime asthma. In addition, approximately 17% reported to have had an attack in the previous year. This implies that in any given classroom of 24 students, an average of 4 students have had an asthma attack before. Visits by the emergency department are key indicators of the severity of asthma and poor control of the asthma. Pittman and Waite (2009) noted that, among Florida residents of age between 5-17 years, the rate of emergency department visits in non-Hispanic blacks is three times more compared to non-Hispanic whites living next to major roads. A separate study conducted by Centers for Disease Control and Prevention in U.S.A. found that, approximately 11.3 million people stay within 150 meters from main roads. By age group, an estimated proportion of people living close to highways included people of ethnic minority and racial communities, population speaking non-English language and foreign-born people. Disparities by poverty and educational attainment were minimal. The percentage of people living near major roads varied from 3.4% for high school graduates to 4.1% for those without a high school diploma. For poverty status, the approximated proportion of people living near main roads was 4.2% for the poor category, a 3.7% for population in the near-poor category and finally 3.5% for non-poor category. In reference to Morris (1948), an estimate of 4% of all Americans live within 150 meters from a main roads, suggesting greater exposure to traffic generated air pollution and increased risk for negative health effects associated with asthma. This analysis suggests that demographic and social disparities exist according to the residential proximity to major highways. The percentage of people exposed to traffic generated air pollution may increase in urban areas due to more roads, higher population density, and higher traffic volume. Recommendations The primary prevention factors to consider in reducing traffic emissions include financial incentives to minimize congestion and vehicle miles travelled (VMT), improving access to alternative transportation options such as cycling, transit and rideshare programs, promoting low emission and electric vehicle usage and diesel retrofitting. In addition, Morris (1948) noted that, secondary prevention strategies are more important in minimizing exposure. These strategies may include land-use policies to limit new development near heavily trafficked roads and mitigation techniques for existing buildings and homes (e.g., improved ventilation systems and roadside barriers). According to studies conducted by Hyman and Vary (1999), solid barriers like noise barriers may be effective at mitigating traffic-related air pollution compared to vegetative barriers like tree stands. Additionally, public health laws are useful in reducing the sighting of new institute ions and schools close to busy traffic corridors and major highways. Conclusion Studies have concluded that residing in homes near high traffic volume will greatly increase the chance of childhood asthma. Children, whose parents do not have a history of asthma and have had long-term exposure, can leave girls more at risk than their counterpart. Furthermore, effective control regulations of vehicular emissions are needed and will prove to be of great importance. Fifty-nine percent of children with asthma, whose parents have no asthmatic history, are a result of living within 75 meters or less to a major road. Therefore, further investigation and research is required to determine and understand why the susceptibility to traffic-related exposure increased in children with non-asthmatic parents. References Hyman, W. A., Vary, D., American Association of State Highway and Transportation American Thoracic Society.,& American Lung Association. (1994). American journal of respiratory and critical care medicine: An official journal of the American Thoracic Society, medical section of the American Lung Association. New York, NY: American Lung Association. Gurney, M. (1998).Personal and social education: An integrated programme. Gustavsson, F. (2008).New transportation research progress. New York: Nova Science Publishers. Officials, National Cooperative Highway Research Program, National Research Council (U.S.), & United States. (1999). Best management practices for environmental issues related to highway and street maintenance. Washington, DC: National Academy Press. Kebbede, G. (2004). Living with urban environmental health risks: The case of Ethiopia. Burlington, VT: Ashgate. Krzyzanowski, M., & Kuna-Dibbert, B. (2005).Health effects of transport-related air pollution. Geneva: World Health Organization. Morel, B., & NATO Advanced Research Workshop on The Role of Risk Assessment in Environmental Security and Emergency Preparedness in the Mediterranean Region. (2006). Environmental security and environmental management: The role of risk assessment ; [based on papers presented at the NATO Advanced Research Workshop on The Role of Risk Assessment in Environmental Security and Emergency Preparedness in the Mediterranean Region, Eilat, Israel, 15-18 April 2004]. Dordrecht: Springer. Morris, A. C. (1948). The Florida handbook. Tallahassee: Peninsular Pub. Co. Bottom of Form National Research Council (É.-U.).(1998). Dynamic impact factors for bridges. Washington, D.C: National Academy Press. Pittman, C., & Waite, M. (2009).Paving paradise: Florida's vanishing wetlands and the failure of no net loss. Gainesville, FL: University Press of Florida. Top of Form Read More