Air Pollution in Ho Chi Minh City, Vietnam
Figure Relative Errors (%) for Estimates of Emission Factors Based on Different Scenarios.
In this research, the improvements to the VMT estimation were proposed which considered both the link attributes and the traffic count information. The proposed model for volume estimation is easy to be calibrated. Case study and model calibration in southwest Houston show that the improved approach is better than both the EPA Traffic Count Method and the nationwide MOBILE6 defaults in terms of the estimation of both VMT and emission factors. In order to apply the improved approach to the real-world networks, more calibrations and validations under various environments are necessary, which will be the next step of this research.
The authors acknowledge that this paper was prepared based on Texas Department of Transportation (TxDOT) research project 0-4142. The authors would also like to thank Mr. Ignacio Barrera-Kelly in helping to collect part of the data for case study.
A Study on the Association of Particulate Air Pollutants and Respiratory Diseases in Metro Manila
Genandrialine L. Peralta, Cherry B. Rivera, Louernie de Sales, and Julius Bañgate
Environmental Engineering Graduate Program
National Engineering Center
University of the Philippines, Diliman
Quezon City, Philippines 1101
In the Philippines, the most common air pollutant being monitored in 11 stations is total suspended particulates (TSP). This study was intended to look into the health implications of ambient air quality in Metro Manila with a view looking at various policy implications to improve the existing environmental and health monitoring systems in the country. The study obtained the Environmental Management Bureau’s monitoring data for TSP from 1995 to 2001 and the morbidity and mortality data from 1995 to 2000 from reports and survey of selected hospitals and health centers. Using GIS software, data gathered from hospital survey and air quality data were combined with other attributes such as demographic, socio-economic profile, and road networks. In the analysis of the TSP concentration versus mortality and morbidity data, there appears to be a close association between TSP data and respiratory disease data from 1995-1997 when the average TSP concentration reached the “unhealthy” level (> 230 g/m3). Motor vehicles were suggested to be the main source of particulates. It was recommended to establish disease surveillance sentinels alongside air quality monitoring stations for better protection of public health and to improve testing of smoke belching vehicles.
Keywords: TSP, monitoring, respiratory diseases, GIS, Metro Manila
This study was intended to look into the health implications of ambient air quality in Metro Manila. Monitoring data of Total Suspended Particulates (TSP) were taken from the Environmental Management Bureau-National Capital Region (EMB-NCR). Data from 1995 - 2001 were raw data from the 11 monitoring stations, which were taken by EMB-NCR every six days while summary results from 1987 up to 1994 were given in maximum, minimum, and annual average concentrations. Morbidity and mortality data from 1995 to 2000 were obtained from the Department of Health (DOH) Center for Health Development –National Capital Region and in selected hospitals and barangay health centers.
2.0 LITERATURE REVIEW
Global initiatives on the investigation of the health effects of environmental pollution especially indoor and outdoor air pollution found solid evidence to prove significant correlation between respiratory diseases and air pollutants.
There were eight major studies on air pollution conducted in Metro Manila in the last 10 years. However, only two out of eight studies are related to health effects of air pollution. There are also past and ongoing activities related to air pollution and air quality monitoring specifically on PM10 sampling and analysis, source apportionment, particle size fractionation and elemental analysis, air quality modeling, GIS applications, database development, as well as formal and continuing education at the Philippine Nuclear Research Insititute, Ateneo de Manila University and the University of the Philippines, Manila and Diliman. However, it was obvious in these past studies that health effects of air pollution were not given enough attention.
Several findings had already established the relationship of air pollution on health, specifically on particulate matter. However, the effect of TSP on mortality has not been confirmed since conflicting results were found. It appears that TSP, as an indicator is not as sensitive as PM10 or PM2.5, which are the inhalable particles that can go directly to the lungs. And since 70% of a person’s time is spent mostly indoor, indoor air quality has a more pronounced effect on health than ambient air.
3.0 EXISTING CONDITIONS AND METHODOLOGY
3.1 Ambient Air Quality Information
In the Philippines, the most common air pollutant that is being monitored is total suspended particulates (TSP). The EMB-NCR currently maintains 11 ambient air quality monitoring stations throughout Metro Manila as shown in Figure 1. The regular schedule is to obtain 24-hour average TSP samples every six days on a rotation basis. The stations are capable of monitoring TSP using high volume samplers. Samples are analyzed using gravimetric method. Because of the sporadic development in Metro Manila, land uses surrounding the ambient air-monitoring stations are a mixture of residential, commercial, institutional, and industrial areas. The data collected by EMB-NCR were reported in annual reports as minimum, maximum, and average data. This study had to obtain the raw data, which were processed and encoded in a database format.
3.2 Health Information System
The health information system in the Philippines is not well established and the centralized database within the national Department of Health is not updated regularly. The Department of Health of each local government is tasked with collecting health statistics, which are submitted, to the central office. However, the records are spotty with occurrence of under-reporting. Hence, the study did a primary survey of 17 representative hospitals and request for specific cases of related diseases such as Pulmonary Tuberculosis, Acute Respiratory Infection, Cardiovascular Diseases, Bronchial Asthma, COPD, Pneumonia, Bronchitis, Allergic Rhinitis, Emphysema, Cough, Phlegm, Wheezing, Cancer of the Lungs, Ischemic Heart Disease, Pulmunary Heart Disease, Congenital Anomaly, Other Related Ailments.
The hospital surveyed were East Ave. Gen Hospital, E. delos Santos Memorial Hospital, St. Luke’s Hospital, United Doctors’ Medical Center, National Children’s Hospital, Philippine General Hospital, Ospital ng Maynila, Manila Medical Center, San Lazaro Hospital, Makati Medical Center, Makati General Hospital, Rizal Medical Center, Cardinal Santos Hospital, Medical City, Manila Central University Hospital, and Caloocan Gen. Hospital, which are all located within polluted areas.
3.3 GIS Database
Data gathered during hospital survey and air quality data from different monitoring stations were incorporated into the GIS software together with other related data such as demographic, socio-economic profile, and road networks. As there was no dispersion modeling in this project, correlation of the data was determined using GIS overlays. To establish relationships between the data layers, simple queries and processing of the data were done and information is presented as thematic maps. Using Surfer, the TSP geometric mean concentrations from 1996 to 2001 were plotted in contour maps as shown in Figure 2. The highest concentration of TSP was formed in Quezon City in 1997 and 2000 where mounds or peaks were observed with light intensities for high concentrations. Figure 1 Ambient Air Quality Monitoring Stations in Metro Manila
4.1 Air quality and health
In general, there has been no significant change in the levels of TSP from 1988 to 1994. However, from 1997 until 2000, the trend in TSP levels in Metro Manila has been decreasing. Notably, there is an increasing trend in the TSP levels in 2001. In the analysis of the TSP concentration and mortality and morbidity data in Figure 3, there appears to be a close association between TSP data and morbidity data from 1995-1997 when the average TSP concentration reached the “unhealthy” level, which is greater than 230 g/m3. TSP does not appear to be sensitive to mortality data as there can be various reasons attributable to death. At the start of 1994, TSP concentration increased to unhealthy level until it gradually decreased to the “fair” level in 1998. Motor vehicles were suspected to contribute to the elevated TSP due to the high traffic density near the air monitoring stations.
Mortality data has been consistently stable through the years whereas morbidity seems to have been affected by TSP levels especially from 1995-1997. However, with limited information, it is difficult to conclude whether TSP concentration has any direct or indirect effect on morbidity and mortality rate. More epidemiological analysis has to be done and the air quality data has to be validated.
In the Philippines, as in other countries, there is too much emphasis on ambient air monitoring. Being a tropical country, there is no combustion of coal for heating or cooking as experienced in other countries. Instead, air pollution mainly comes from motor vehicles, stationary sources (industry and power plants), and smoke (tobacco and backyard burning). The following confounders were identified that could have affected the air quality in Metro Manila (NCR) or may have contributed to the diseases surveyed in the study:
5. CONCLUSIONS AND RECOMMENDATIONS
It is rather difficult to conclude whether there is an association between TSP and health in general. However, in our findings, morbidity has showed a tendency to be linked with elevated concentrations of TSP perhaps due to acute symptoms manifested early on due to air pollution. Mortality does not appear to have any clear correlation with TSP. The following recommendations are proposed for future consideration:
The collection and processing of health statistics was included in the devolution of powers to the local government units. Hence, there is no centralized collection by the national Department of Health as in the past. To avoid duplication of efforts within cities and towns, several disease surveillance points (DSP) can be established to serve as public health monitoring sentinels to form national DSP system. A DSP can represent, say 10,000 population, collecting mortality and morbidity data identifying various causes. Hospitals and health centers can feed into the DSP information system. External support is necessary to initiate the DSP system with a view to making it sustainable after several years and regular funds have been allocated from government or NGOs.
Note: Intensity of TSP concentration increases as the color lightens.
Figure 2. TSP Geometric Mean Contour Maps
Figure 3 Average TSP Concentration, Morbidity and Mortality Data for the National Capital Region
B. Study on the effects of indoor air pollution
Indoor air quality is necessary in establishing the relationship between air pollution and public health. An average person spends 70-80% of his/her day indoors whether at home, school, office, factory and entertainment hence the exposure to outdoor air is much less than indoor air. The tendency to attribute respiratory diseases to outdoor air pollution may not be valid considering that most of the studies regarding air pollution in the Philippines is focused on ambient air quality.
C. Strict implementation of laws and regulations
In order to improve the air quality in Metro Manila, there should be a determined public advocacy for political and regulatory action from all citizens and sectors. The policymakers and regulatory agencies should implement stricter air pollution standards particularly for rapidly growing cities and to enforce anti-smoke belching inspections and campaigns.
The authors would like to thank the Asian Development Bank, Manila for supporting this short study.
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