Challenges in Bogota Air Quality: Policies and Technology

Transcription

1 Challenges in Bogota Air Quality: Policies and Technology Extended abstract # 58 vbcrlf Jorge E. Pachon Universidad de La Salle. School of Environmental Engineering. Bogota, Colombia. Georgia Institute of Technology. School of Civil and Environmental Engineering. 311 Ferst Drive, Atlanta, GA Eduardo Behrentz Universidad de Los Andes. Environmental Engineering Research Center. Bogota, Colombia. Néstor Y. Rojas Universidad Nacional de Colombia. Department of Chemical Engineering. Bogota, Colombia. Transversal 30A 40-04, Chemical Engineering Laboratory, Of Introduction Due both its increasing emissions inventory and lack of effective environmental policies, Bogota, Colombia s capital and largest city, has become one of the most air polluted cities in Latin America. During the last 10 years, annual concentration of PM10 has exceeded the standard in several parts of the city. The decline in the city s air quality is explained by technological and policies issues. Even though the correlation between diesel-vehicle particulate matter emissions and the sulfur content of the fuel is widely documented, little has been done to improve the quality of the diesel fuel, in terms of its environmental performance. The current sulfur content of the diesel fuel sold in Bogota (1,200 ppm) is higher than that found in major Latin American cities. It is, however, lower than that of the diesel sold in the rest of the country 4500 ppm -. Notwithstanding the successful implementation of the new bus-rapid-transit (BRT) system, the city s transit bus fleet is old and oversized and responsible for more than 90% of the PM 10 emissions generated by mobile sources. During a recent public transportation strike, where most of public buses not associated to the BRT system did not run, the concentration of PM 10 in the city dropped 54% with respect to the same day in the previous week. This paper analyses the gaps in the air quality management strategies in Bogota and recommends the steps to fill such gaps, based on the opportunities given by the public awareness to the problem, the state of local scientific knowledge and the current political will to finally curb air pollution. Bogota s Air Quality Air quality has been widely related to health problems on main urban centers 1. Historically, Mexico City and Santiago have been demonstrated as cities with the worst air quality in Latin America, and therefore, are associated with strong implications on

2 public health 2,3. During the last few years, Bogota s air quality has been continuously deteriorating, showing noncompliance with air quality local standards 4,5. It has been estimated that mobile sources are the main cause of air pollution in major Latin American cities 6, particularly those located at high elevation like Bogota. Given both significant emission rates and stable meteorological conditions, poor air quality can contribute considerably to disease and hospital rates for high risk populations such as children and elderly people 7. Air pollution also reduces visibility and has direct effects on climate change 8. Bogota, Colombia s capital and largest city is located at 2,660 m (8,700 feet) above MSL, with 6.8 million inhabitants 9. Bogota s economy is the biggest in the country, and grows at an accelerated rate. Bogota has approximately 4,700 industries 10 and 1.1 million vehicles 11, of which more than 90% being private. Bogota s air quality network (BAQN) consists of 14 stations distributed throughout the city that have been monitoring criteria pollutants since 1997 (Figure 1). Figure 1. Location of Air Quality Monitoring Stations in Bogota Through the years, particulate matter has become the most concerning pollutant, accounting for the majority of non-attainment days, as it can be seen in Figure 2. The PM10 annual standard in Bogota has been gradually become more stringent since 2003, beginning with 80 ug/m 3 and curbed to 55 ug/m 3 by The intention is to reach the international standard (50 ug/m 3 ) by Although PM2.5 is not measured permanently by the Bogota s Air Quality Monitoring Network, experimental studies have found a PM 2.5 /PM 10 ratio between 0.45 and 0.75 varying with the location of the monitoring stations in the city 13, 14. Annual PM2.5 might be estimated between 30 and 50 ug/m 3 in this way. These values are above PM2.5 US-EPA annual standard (15 ug/m 3 ). 2

3 Figure 2. PM10 annual average concentration over Bogota ug/m years Annual concentrations Local standard Source: Bogota s Air Quality Network Health Implications Poor air quality over Bogota can also be confirmed on health implications. It has been widely demonstrated that children s health is especially affected by air pollution 15. Up to June 2006, 80 children younger than five years old have died in Bogota and this has been attributed to air pollution 16. Air quality in urban centers in Latin America is shown in a recent report from the World Health Organization, in which the relationship between morbidity and mortality, and poor air quality on main urban centers is demonstrated 1. For the case of Bogota, it has been observed that an increase of 10 ug/m 3 in the PM10 concentration is associated to an increase of at least 8% in the number of hospital visits for respiratory illness in children less than 14 years old 17. This information was recently updated, finding that the same increase in the PM 10 concentration is associated to a 4% in the number of hospital admissions for Acute Respiratory Infections (ARI) 18. Causes The city s air quality deterioration is explained by technological and political issues. Bogota has approximately 4,700 point sources where coal, fuel oil, diesel and natural gas are used in heaters and boilers. Most of these facilities do not have adequate emission control devices, or programs to reduce and prevent air pollution. On the other hand, diesel vehicles emit large amounts of PM 10, accounting for more than 50% of the total PM 10 emissions 19. During a recent public transportation strike, the concentration of PM 10 in the city declined 54% with respect to the same day in the previous week (2005), showing the big impact of mobile sources. Furthermore, from an exposure assessment, these emissions have a stronger influence perspective than point sources 5. Nowadays, Bogota s fleet is composed by nearly one million private vehicles and 80,000 public transit vehicles. Seven years ago, Bogota had 420,000 vehicles 10, meaning that an increase of more than 100% took place during this period of time. Heavy duty vehicles use mainly diesel as a predominant fuel. The sulfur content of the diesel in Bogota is 1,200 ppm, while in the rest of the country, it is as high as 4,500 ppm. During 3

4 combustion, sulfur produces sulfur oxides which can act as condensation nuclei, forming aerosols. This is the main mechanism leading to the formation of particulate matter within the city, largely emissions by mobile sources. In addition to a deficient fuel quality, the lack of strong policies on public transportation and a low control capacity by environmental authorities has allowed a public bus fleet oversized by more than 50% in the city. Since most of the buses are not owned by companies, but work under a rather informal system, they do not have regular maintenance nor adequate driving conditions. This further exacerbates emissions to the atmosphere. Lax policies on urban growth has worsened the problem, allowing people settlements to form within industrial zones, in areas close to the airport and close to the main city s waste landfill. Challenges Public awareness about air pollution has been increasing in the last three years. A gray thick smog layer over the city during frequent thermal inversion episodes, an undoubted sign of air pollution, has increased the number of people complaints on air quality. Public outreach led by academics and professionals and coverage by local news are also helpful in spreading concern. Recent reports on children mortality caused by air pollution are of major apprehension of the population. Big challenges to curb the problem are on the way. Universities and news media are putting pressure on the national government to improve diesel quality, a measure that will readily decrease the air pollution problem. A number of lawmakers are aware of the situation and are promoting changes in legislation in order to speed up the fuel sulfur phase down process and increase the capacity of environmental authorities to control high emitters. The Bogota s Secretary of the Environment, the city s environmental authority, has focused on measures to reduce air pollutant emissions, both from mobile and point sources. Measures for mobile sources include inspection and maintenance programs for vehicles, use of substitute fuels, on-road identification of high emitters, educational programs for truck and bus drivers, and restrictions for 15-20% of public and private vehicles during peak hours of the day, according to the last number of the license plate. Difficulties arise when public bus drivers react against control measures taken by authorities, stating that such measures create social inequity and bring poverty to thousands of families. Air pollution from point sources is being controlled by limiting the consumption of coal, fuel oil and diesel in heaters and boilers, particularly in areas with high concentrations of PM 10, such as western Bogota which was recently declared a source area of air pollution. New legislation has been issued with more restriction on emissions and on ambient air quality standards, but the law is still lacking any real control mechanisms. Despite such great efforts made by Bogota s district, the effectiveness of measures has been low, owing to the lack of a structural air quality improvement plan, with the participation of all sectors. Realistic short and long term goals and targets, together with enough funds and a strong political decision to overcome difficulties and resistance to change will avoid air quality to keep being deteriorated. Only in this way, 4

5 Bogota would reach a better air quality and less children will get sick because air contaminants. References 1. CEPIS. OMS. Guidelines for Air Quality, Lima, Castillejos Salazar, Margarita. Caracterización de las circunstancias clínicas y epidemiológicas que rodean las muertes en días de alta y baja concentración de partículas (PM 10 y PM 2.5 ) y otros contaminantes atmosféricos en la zona suroeste del área metropolitana de la ciudad de México. Universidad Autónoma Metropolitana de México, O Ryan, Raul and Sepulveda, Luis. Contaminacion del aire en Santiago: Qué es, que se ha hecho, que falta?. Perspectivas, Universidad de Chile, vol. 4, No. 1, 2000, p Molina, Mario and Molina, Luisa. Megacities and Atmospheric Pollution. J. Air & Waste Manage. Assoc. 54: Behrentz, Eduardo. Comparative Assessment of Road Transport Emission Inventories in Five Metropolitan Areas of South America. Open Conference of the Global Emissions Inventory Activity Project. Paris, France. November 29, December 1 st, Faiz, Asif; Gautam, Surhid and Burki, Emaad. Air pollution from motor vehicles: issues and options for Latin American countries. The Science of the Total Environment 169 (1995) EPA. Air Quality Index: A Guide to Air Quality and Your Health Rojas, Nestor. Material particulado atmosferico y Salud. Universidad de Los Andes, Bogota, DANE. Departamento Nacional de Estadisticas Colombia. Censo poblacional Universidad de Los Andes (Uniandes). Diseño e implementación de un modelo de calidad del aire para Bogotá. Bogotá, El Tiempo. Sobreoferta de vehiculos en Bogota DAMA (Departamento Administrativo del Medio Ambiente). Resolucion 1208 de Normas de calidad del aire. 13. Larsen, Cost of environmental damage: A Socio-Economic and Environmental Health Risk Assessment. 14. Rojas, Néstor y Gálvis, Boris. Relación entre PM2.5 y PM10 en la ciudad de Bogotá. Revista de Ingeniería No. 22, Universidad de Los Andes, noviembre CEPIS. Effects of air pollution on children s health and development. WHO, Europe Secretaria Distrital de Salud de Bogota (SDS). Boletin ERA No 25, Agosto Solarte, Iván. Contaminación atmosférica y Enfermedad Respiratoria Aguda en menores de 14 años en Bogotá. Pontificia Universidad Javeriana, Bogotá, Pachon, Jorge Estimación del riesgo en la salud humana a partir de la caracterización de aerosoles en la Localidad de Puente Aranda en la ciudad de Bogotá. Universidad de La Salle. Bogota. 19. Giraldo, L.A. and Behrentz, E. Estimación del inventario de emisiones de fuentes móviles para la ciudad de Bogotá e identificación de variables pertinentes. Universidad de Los Andes

6 Key words: Bogota, air quality, developing countries, diesel, health 6