Showing papers by "Maureen L. Cropper published in 1997"

Roads, Population Pressures, and Deforestation in Thailand, 1976-89

Abstract: Population pressures play less of a role in deforestation than earlier studies of Thailand found. Between 1976 and 1989, Thailand lost 28 percent of its forest cover. To analyze how road building, population pressure, and geophysical factors affected deforestation in Thailand during that period, Cropper, Griffiths, and Mani develop a model in which the amount of land cleared, the number of agricultural households, and the size of the road network are jointly determined. The model assumes that the amount of land cleared reflects an equilibrium in the land market. Hence, in the long run, the amount cleared depends on the profitability of agriculture and on the long-run costs of clearing. The size of the country's agricultural population, as well as the size of the road network, affects the demand for cleared land and hence the amount cleared in equilibrium. The authors estimate an equation to explain the amount of land cleared in equilibrium, using data for the 58 provinces that were forested in 1973. Data from five years (1976, 1978, 1982, 1985, and 1989) are combined to estimate the equilibrium model. They find that the number of agricultural households and road density both increase the fraction of each provinced cleared, but their effects are small. The elasticity of cleared land with respect to agricultural households is only 0.12; with respect to road density, it is only 0.26. These effects do differ by region, however; moreover, the elasticities of forest area with respect to population density and road density are larger in absolute value than the respective elasticities for cleared land. The elasticity of forest-to-total area with respect to population density is -0.41 for the North/Northeast section of the country and -0.22 for the South/Central region. The corresponding elasticities with respect to road density are -0.20 and -1.09. This suggests that population pressures play less of a role in deforestation than earlier studies of Thailand found. For an area to remain deforested, it must be profitable to convert the land to another use, and that use is usually agriculture. Steep slopes and poor soil quality provide some natural protection for forests, although the quantitative impact of those factors vary. Variations in agricultural prices also affect the amount of deforestation. This paper - a product of the Environment, Infrastructure, and Agriculture Division, Policy Research Department - is part of a larger effort in the department to understand the forces affecting land use change. The study was funded by the Bank's Research Support Budget under research project Population Growth and the Environment (RPO 678-59).

The Health Benefits of Air Pollution Control in Delhi

Abstract: An important reason for controlling air pollutants such as particulate matter or sulfur dioxide is the damaging effects they have on human health. These effects include premature death as well as increases in the incidence of chronic heart and lung disease. Estimates of the health damages associated with air pollution are important because they can provide both an impetus for environmental controls and a means of evaluating the benefits of specific pollution control policies. To estimate the health damages associated with air pollution in developing countries, policy makers are often forced to extrapolate results from studies conducted in industrialized countries. These extrapolations, however, may be inappropriate for two reasons. First, it is not clear that the relationships found between pollution and health at the relatively low levels of pollution experienced in industrialized countries hold for the extremely high pollution levels witnessed in developing countries. Levels of particulate matter, for instance, are often three to four times higher in developing countries than in industrialized ones. Second, in developing countries, people die at younger ages and from different causes than do people in industrialized countries, implying that extrapolations of the impacts of air pollution on mortality may be especially misleading. This paper reports the results of a study relating levels of particulate matter to daily deaths in Delhi, India, between 1991 and 1994. We focus on Delhi, the capital of India, because it is one of the world's most polluted cities. Between 1991 and 1994, the average total suspended particulate (TSP) level in Delhi was 375 micrograms per cubic meter-approximately five times the annual average standard of the World Health Organization (WHO). Levels of TSP in Delhi during this time period exceeded WHO's twenty-four-hour standard on 97% of all days on which readings were taken. Although particulate matter-produced by motor vehicles, smelters, the burning of refuse, and two coal-fired power plants-is Delhi's main air pollution problem, levels of sulfur dioxide (SO2) and oxides of nitrogen (NOx) are below U.S. limits.

The Health Effects of Air Pollution in Delhi, India

Abstract: Particulate air pollution has less overall impact on nontraumatic deaths in Delhi, India, than in U.S. cities. But the deaths occur earlier in life in Delhi, which could mean a larger loss in life-years. Cropper, Simon, Alberini, and Sharma report the results of a time-series study of the impact of particulate air pollution on daily mortality in Delhi. They find: A positive, significant relationship between particulate pollution and daily nontraumatic deaths as well as deaths from certain causes (respiratory and cardiovascular problems) and for certain age groups. In general, these impacts are smaller than those estimated for other countries, where on average a 100-microgram increase in total suspended particulates (TSP) leads to a 6-percent increase in nontraumatic mortality. In Delhi, such an increase in TSP is associated with a 2.3-percent increase in deaths. The differences in magnitudes of the effects are most likely explained by differences in distributions of age at death and cause of death, as most deaths in Delhi occur before the age of 65 and are not attributed to causes with a strong association with air pollution. Although air pollution seems to have less impact on mortality counts in Delhi, the number of life-years saved per death avoided is greater in Delhi than in U.S. cities-because the age distribution of impacts in these two places varies. In the United States particulates have the greatest influence on daily deaths among persons 65 and older. In Delhi, they have the greatest impact in the 15-to-44 age group. That means that for each death associated with air pollution, on average more life-years would be saved in Delhi than in the United States. Large differences in the magnitude of effects do call into question the validity of the concentration-response transfer procedure. In that procedure, concentration-response relationships found for industrial countries are applied to cities in developing countries with little or no adjustment, to estimate the effects of pollution on daily mortality. This paper-a product of Development Economics Research Group-is part of a larger effort in the group to examine the benefits and costs of pollution control. The study was funded by the Bank's Research Support Budget under research project Measuring the Health Effects of Air Pollution in Developing Countries: The Case of Delhi, India (RPO 679-96). Maureen Cropper may be contacted at mcropper@worldbank.org.

Is there a role for benefit-cost analysis in environmental, health, and safety regulation?

Abstract: The growing impact of regulations on the economy has led both Congress and the Administration to search for new ways of reforming the regulatory process. Many of these initiatives call for greater reliance on the use of economic analysis in the development and evaluation of regulations. One specific approach being advocated is benefit-cost analysis, an economic tool for comparing the desirable and undesirable impacts of proposed policies.

The Health Effects of Air Pollution in Delhi, India

Abstract: The authors report the results of a time-series study of the impact of particulate air pollution on daily mortality in Delhi. They find: a) A positive, significant relationship between particulate pollution and daily nontraumatic deaths as well as deaths from certain causes (respiratory and cardiovascular problems) and for certain age groups. b) In general, these impacts are smaller than those estimated for other countries, where on average a 100-microgram increase in total suspended particulates (TSP) leads to a 6-percent increase in nontraumatic mortality. In Delhi, such an increase in TSP is associated with a 2.3-percent increase in deaths. c) The differences in magnitudes of the effects are most likely explained by differences in distributions of age at death and cause of death, as most deaths in Delhi occur before the age of 65 and are not attributed to causes with a strong association with air pollution. d) Although air pollution seems to have less impact on mortality counts in Delhi, the number of life-years saved per death avoided is greater in Delhi than in US cities -- because the age distribution of impacts in these two places varies. In the United States particulates have the greatest influence on daily deaths among persons 65 and older. In Delhi, they have the greatest impact in the 15-to-44 age group. That means that for each death associated with air pollution, on average more life-years would be saved in Delhi than in the United States. Large differences in the magnitude of effects do call into question the validity of the"concentration-response transfer"procedure. In that procedure, concentration-response relationships found for industrial countries are applied to cities in developing countries with little or no adjustment, to estimate the effects of pollution on daily mortality.

Roads, population pressures, and deforestation in Thailand, 1976-89

Abstract: Tropical deforestation is considered one of the major environmental disasters of the 20th century, although there have been few careful studies of its causes. This paper examines the causes of deforestation in Thailand between 1976 and 1989, a period when the country lost 28% of its forest cover. This paper takes the perspective that, in the long run, the determinants of deforestation are the determinants of land use change. While logging and fuelwood gathering may remove forest cover, regrowth will occur, at least in moist tropical forests. For an area to remain deforested, it must be profitable to convert the land to another use, and this use is usually agricultural. In Thailand, for example, agricultural land increased between 1961 and 1988; during the same period, forest land decreased. This paper focuses on what, in equilibrium, determines the amount of land cleared for agriculture. The authors emphasize the quantitative impact of two forces--roads and population pressures--that increase the profitability of converting forest land to agriculture. As aerial maps show, development follows road networks. The magnitude of the impact of roads on commercial and subsistence agriculture depends on soil quality along the road. In this case the Thailand government undertook a road-building program in the Northeast section in the 1970's to encourage settlement of that region as a bulwark against Communist encroachment from Laos. Road building very likely spurred deforestation in the Northeast during the 1970's and 1980's, although the magnitude of its impact is not known. Thailand also experienced rapid population growth during this same period, which may have contributed to deforestation in two ways: the growing population demanding more food, increased the demand for agricultural land; and more importantly, in rural areas where other economic opportunities are limited and squatters are permitted on forest lands, a growing population increased the demand for land for subsistence agriculture. The authors conclude that population pressures play less of a role in deforestation than was found in earlier studies on Thailand. Affecting the amount of deforestation are other factors, such as the profitability of converting the land to another use, natural protection for forests like poor soil and steep slopes, and agricultural price variations.