Air pollution measurements show that particulate pollution is the most significant pollutant inside the Kathmandu valley (Devkota, 1993; Karmacharya et. al., 1993; Otaki et. al., 1995; Shah and Nagpal, 1997). The impact of air pollution on health in the Kathmandu valley can be assessed by the increase in the number of patients suffering from diseases related to air pollution. There has been no real epidemiological study in Nepal to assess the impact of air pollution on public health, primary reason being poor hospital and air quality information. However, a number of dose-response relationships have been studied in Nepal.

There are several studies conducted in the valley which suggest adverse health outcome of air pollution. One of the first such studies was conducted by Pandey and Neupane (1984). The study reviewed the case of discharge of the ten hospitals with a combined capacity of 265 beds in 1971 and found that ARI accounted for 32.1% of mortality for infant (less than 1 year of age) and 11.2% for children between 1-4 years of age. Analysis of the data from Kanti Children Hospital, Kathmandu, by the same author during the one year period (April 1982 to March 1983) showed that out of 3,319 cases admitted, 1,256 cases (37.8%) were admitted due to ARI.

The World Bank study (Shah and Nagpal, 1997), using dose-response equation developed in US and 41 ìg/m³ as the benchmark for PM10, stated that in 1990 PM10 pollution caused 84 excess deaths, 475,298 restricted activity days, 1.5 million respiratory symptom days, 99 respiratory hospital admissions among other health problems. The monetary value attached to these impacts totaled Rs 210 million out of which Rs 28 million attributed to excess deaths. Using the prevalent exchange rate (1 US$ = Rs 29.37, 1990), the above figure amounts to US$ 7.15 million and US$ 0.95 million respectively. In this study, the cost of hospital admission was only 0.2 % of the total cost of PM10 pollution. It also estimated that among the sources of air pollution, traffic (exhaust and re-suspension) had the largest impact on health. It was estimated that reduction of vehicle exhaust emissions was the most effective in terms of reduced health damage, Rs 341 per Kg emission reduction (i.e. savings of US$ 11.61 per Kg reduction in emission).

The World Bank study had some major limitations; it was based on the epidemiological studies conducted in US. Similarly it assumed threshold level of 41 ìg/m³ for PM10; however WHO has admitted that no such threshold exists.

Child Workers in Nepal (CWIN) (1997) studied the health impacts of air pollution on a particular vulnerable group inside the valley for the first time. CWIN conducted a survey of 60 children working as conductors (helpers) in tempos (65 % of them were below 14 years of age) and examined the health (including chest X-ray and blood test) of 38 of these children in the survey, 42 % of the children said that they had been sick during work. Other health complains were eye problem (84%), chest pain (82%), headaches and nausea (58%), fever (53%), cough and cold (55%), difficulty in breathing (45%), pneumonia, tuberculosis, bronchitis and chest problems (29%), anemia (18%), skin problems (21%). The study also estimated that these children work for about 14 hours each day hanging behind the tempos just above the emission pipe; they breathe 4,116 ìg of PM10, 1,255 ìg of NOx (Oxides of Nitrogen) and 17,687 ìg of Total Suspended Particles (TSP) each day.

The report by LEADERS Nepal (1998) also analyzed the hospital records for the respiratory diseases especially on children. It was found that urban residents exceeded the number of respiratory related cases in the hospital compared to that from the rural area in Kathmandu.

Nepal Environmental and Scientific Services Private Limited (NESS) did a similar assessment as that of World Bank in 2001 using threshold concentration of 40 ìg/m³ and concluded that the respiratory problem caused by air pollution cost the country about Rs 30 to 55 million per year. It estimated that PM10 pollution cause 92 premature deaths annually among children < 5 years and about 65,000 cases of respiratory problems. This study attempted to update the World Bank study however it suffered from similar limitations as the former.

Two students’ from St. Xavier’s campus have done dissertation on health impact of air pollution. Shakya (2001) studied impact air pollution on traffic police; questionnaire survey of 90 traffic police, unstructured interview of 20 and observation in field and medical tests (oxy-hemoglobin and flow meter test) of 15 traffic police was conducted. The main findings of the study are:

• Impact on nervous system ranged between 58-74% including dizziness, depression, headaches, forgetfulness, irritation, lack of concentration, etc.
• Impact on respiratory system ranged between 26-87% including severe cold, asthma, cough, sneezing, nose irritation, low resistance to influenza.
• Impact on cardio-vascular system ranged from 39-63% including rapid heartbeat, chest pain, high blood pressure anemia.
• Other impacts included reddening of eyes, watery and burning sensation in the eyes and reduction in vision.

Shrestha (2002) analyzed records of respiratory illness in main hospital of Kathmandu valley ( Bir hospital, Patan hospital, Kanti Children hospital and Tribhuvan University Teaching Hospital) and found that increasing number of patients were diagnosed with respiratory problems over the period of five years. Shrestha concluded that this increase in prevalence of respiratory illness is due to the rising level od particulate concentration in Kathmandu’s air.

Tuladhar and Raut (2002) conducted a study on the impact of brick kilns on the health of children living next to the kilns. A survey of people living in an area with brick kilns as well as control area indicated that people living near brick kilns are more likely to suffer from illness related to air pollution compared to similar people living in an area without kilns. Similarly, a medical examination of children attending school in an area with brick kilns (High View School of Tikathali) and a school in an area without kilns (Valley Public School) showed that the kilns adversely affected the health of young children (under the age of six) exposed to the pollution. The study also showed that the PM10 in the area with the kilns was about three times higher than PM10 levels in an area without the kilns. Some of the key findings of the survey are as follows:

• Out of 290 individuals surveyed, 54 % from area with brick kilns reported symptoms of respiratory disorders compared to 41 % in the control area.
• Elderly people were the most affected from respiratory disorders in both the areas. This was followed by children up to the age of 4 years.

According to study done by Clean Energy Nepal (CEN) and Environment and Public Health Organization (ENPHO) (2003) records of 369 COPD patients and 315 control patients admitted to Patan Hospital from April 1992 to April 1994 and revealed that the odds of having COPD are 1.96 time higher for Kathmandu valley residents compared to outside valley residents. An analysis of hospital records from three major hospitals in Kathmandu indicated that the number of COPD patients admitted to hospital, as well as the percentage of COPD patients as a percentage of total medical patients has increased significantly in the last 10 years and it was the number one killer of adult patients in the hospital. Records also indicated that the number of COPD patients was highest in the dry winter months, when air pollution is at its peak and elder sub-population is most vulnerable to respiratory illness. The study further estimated that reduction of PM2.5 level in Kathmandu by half of the existing (47.4 µg/m3) will result in reduction in daily mortality by 7% and hospital admissions by 24%. Similarly, reduction in the annual average PM10 level in Kathmandu to international standard (50 µg/m3) will avoid over 2,000 hospital admissions, over 40,000 emergency room visits, approximately 135,000 cases of acute bronchitis in children, over 4,000 cases of chronic bronchitis and half a million asthma attacks.

Rana (2004) assessed air quality of Birgunj and Pokhara and concluded that TSP and PM10 were the pollutants of primary concern and gaseous pollutants like oxides of Nitrogen (NOx), oxides of Sulphur (SOx), Carbon mono oxide (CO) were below the National Ambient Air Quality (NAAQ) standards. Similar conclusions were drawn for the valley and stated that Putalisadak and Matsyagaon were the most polluted and the least polluted locations inside the valley respectively. The study also assessed the environmental burden of disease due to outdoor air pollution; for this WHO guideline was used. In case of Kathmandu valley, the attributable burden due to current PM10 concentration in Kathmandu valley against the baseline concentration of 10 µg/m3 was found out to be 1,926 cases of premature mortality per year (lower and upper bounds of 1,184 and 2,973, respectively). Similarly, the number of cases of premature mortality from short-term exposure to current PM10 concentration in Kathmandu valley which could be avoided if the government could reduce the ambient PM10 concentration to national standard was calculated to be 212 cases of premature mortality per year, with upper and lower boundary to be 127 and 338 respectively.

Saraf (2005) mentioned that ARI is one of the major public health problems and is ranked as top three diseases affecting morbidity among children below 5 years of age in Nepal; its incidence in 2003 was 136 per 1000 children in 0-4 age group inside Kathmandu valley. Hence, control of ARI is an important component of the child survival program in the Department of Health Services. The study estimated dose-response relation between PM10 and number of ARI related hospitalization in children in Kathmandu valley, controlling for major confounding variables like temperature, precipitation and relative humidity. A multiple (log-linear) regression model was formulated and robust regression coefficients (corrected for auto-correlation) and elasticities were estimated for respective explanatory variables. The descriptive statistics showed negative correlation coefficient between PM10 and meteorological variables. Similarly, a positive and statistically significant (at 10% level of significance) partial regression coefficient was obtained for PM10. The study estimated that 1% point increase in PM10 results in about 0.544% point (95% Confidence interval: 0.098, 1.247) increase in number ARI patients. The study further estimated average Cost-of-Illness per episode of ARI related hospital admission which amounted to Rs 5279 (95% CI: 3069.83, 7488.16). Using the central estimate, the total monetary value attributable to ARI related hospitalization among children in the valley was estimated to Rs 2 million and Rs 5.4 million for year 2002 and 2003 respectively.

Khanal and Shrestha (2005) quantified health effects associated with ambient air pollution by building exposure-response model based upon time series data. The Generalized Linear Model (GLM) with log link function was used in the analysis, controlling for temperature and seasonal variable. The study found positive association between various health effects and ambient air pollution. The estimated (central estimate) percent increase in all cause mortality, respiratory mortality, respiratory hospital admissions, COPD hospital admission and lung cancer hospital admissions per 10 µg/m3 increase in PM10 are 0.69%, 3.48%, 1.92%, 3.22% and 3.06% respectively. The corresponding relative risk for average ambient PM10 exposure above the threshold limit (10 µg/m3 ) are 1.0856, 1.5178, 1.2609, 1.4722 and 1.4437 respectively. The study also estimated Environmental Burden of Disease (EDB) for each risk factor considered in the study. The estimated attributable fractions are 0.0788 (7.88%), 0.3411 (34.11%), 0.2609 (26.09%), 0.3207 (32.07%) and 0.3073 (30.73%) for all cause mortality, respiratory mortality, respiratory hospital admissions, COPD hospital admission and lung cancer hospital admissions respectively. The coefficients of PM10 are found to be statistically significant for respiratory morbidity and COPD morbidity and insignificant for others at 95% confidence level. EDB attributable to ambient air pollution exposure with respect to PM10 has been calculated for 20 µg/m3 and 10 µg/m3 baseline PM10 level. Total deaths or burden has been estimated by taking population of Kathmandu valley for 2004 as 1,840,111 and CDR as 9.22 per 1000 population. Morbidities have been expressed in terms of total hospital admissions and OPD visits in the absence of population prevalence rates. Out of total 16,966 deaths, 1,337 cases of deaths can be attributed to ambient air pollution taking threshold limit as 10 µg/m3 for PM10 for the year 2004. Similarly, out of 236 respiratory deaths, 3,188 respiratory hospital admissions, 15,948 COPD and 122 lung cancer hospital admissions, 32, 660, 5,115 and 37 cases respectively can be attributed to the risk factor for the year 2003/2004.

References

CEN & ENPHO. (2003). Health Impacts of Kathmandu’s Air Pollution. Kathmandu: Kathmandu Electric Vehicle Alliance.

CWIN (1997). Tempo Khalassi Baal Sramikharuko Shthiti. Kathmandu: Child Workers in Nepal.

Devkota, S. R. (1993). Ambient Air Quality Monitoring in Kathmandu Valley. Kathmandu Valley Vehicular Emission Control Project Report. UNDP/92-034.

Karmacharya, A. P., Shrestha, R. K. (1993). Air Quality Assessment in Kathmandu City. Report submitted to Department of Housing & Urban Development.

Khanal, R. H. & Shrestha, S. L. (2005). Development of procedures and the assessment of EDB of local levels due to major environmental risk factors. Submitted to Nepal Health Research Council, Kathmandu.

LEADERS Nepal. (1998). A Citizens Report on Air Pollution in Kathmandu : Children’s Health at Risk. Kathmandu: LEADERS Nepal.

NESS (2001). WHO / PoA No. NEP PHE 001. Result no. 8. Kathmandu: Nepal Health Research Council.

Otaki. K., Shamra, T., & Updhyaya, N. P. (1995). Respirable air particulate potential of Kathmandu Municipality. Research on Environmental pollution and management.

Pandey, D. R., & Neupane, M. R. (1984). "Acute Respiratory Infections (ARI) in Infants and Children in Nepal." Souvenir Nepal Journal, 3(1).

Rana, R. S. (2004). Assessment of Ambient Air Quality in Selected Urban Areas of Nepal. Kathmandu: Nepal Health Research Council.

Saraf, A. (2005). Economic Impact of Air Pollution in Kathmandu Valley: An Assessment of Cost of Morbidity in Children. An unpublished Master’s Thesis submitted to Patan Multiple Campus, Lalitpur.

Shah, J. & Nagpal, T. (eds.) (1997). Urban Air Quality Management Strategy in Asia: Kathmandu Valley Report. The World Bank.

Shakya, S. (2001). Health Problems Prevalent in the Traffic Police Personnel due to Vehicular Air Pollution in Kathmandu. Dissertation submitted in partial fulfillment of the requirement of the requirements of the degree of Bachelor of Science (Environmental Science), St. Xavier’s College, Kathmandu.

Shrestha, P. (2002). Study on Prevalence of Respiratory Illness in Kathmandu valley due to Suspended Particulate Matter. Dissertation submitted in partial fulfillment of the requirement of the requirements of the degree of Bachelor of Science (Environmental Science), St. Xavier’s College, Kathmandu.

Tuladhar, B., & Raut, A. K. (2002). Environment and Health Impacts of Kathmandu’s Brick Kilns. Kathmandu: CEN Nepal.

Anuja Saraf (email: frontline@wlink.com.np) is a Nepalese citizen and a Masters' degree holder in Economics from the Tribhuvan University, Nepal. She has completed a thesis on "Economic impact of particulate pollution among children in Nepal entitled Economic Impact of Air Pollution in Kathmandu Valley: An Assessment of Cost of Morbidity in Children"