Air Pollution in Small Towns of Nepal

Most of the air pollution studies conducted in Nepal were focused on Kathmandu Valley only and very few in small towns or semi-urban areas. Present study comprised of air quality monitoring during the day time at three municipalities in Kavre district of Nepal. The study was conducted in order to establish a baseline air quality data for those municipalities as the first time ever in the district. In each of the municipalities three air monitoring stations were established representing industrial, commercial and residential areas. PM10 have been estimated from air sampling programme which spanned 7 months and a total of 126 days reflecting all the three seasons. Envirotech APM 550 Fine Particle Sampler was used for estimation of the PM10. The study found that during winter season the concentration of PM10 was more and among the areas commercial area noted highest level pollution. The mean, mimimum and maximum level of PM10 was found to be 188.02µg/m3, 56.31µg/m3, 510.23µg/m3. The seasonal trend in pollution levels show that winter > pre-monsoon > monsoon. The pollution concentration trend noted among the areas was commercial > industrial > residential on almost all the occasions except at pre-monsoon season between industrial and residential area in Banepa.

INTRODUCTION:

Nepal, a relatively small country with 1,47,181 sq km area inhabited by 22 million people, is known for exquisite environment. However, the real scenario is quite different because urban areas are environmentally degrading due to rapid unplanned urbanization and industrialization. Increasing numbers of human population, industries and automobiles, decreasing agricultural productivity, the frequent occurrence of floods in the lowlands, landslides in the midlands and forest fire are major environmental issues, and recent studies reveal that even the glorious mountain peaks of the high Himalayas have also undergone incipients pollution (Dokiya et al., 1992; Shrestha et al., 1997). Air pollution is considered to be one of the serious and prominent types of environmental pollution that is prevalent in most industrial towns and cosmopolitan cities of the world. It had been a general impression in the past that air pollution is exclusively a problem of the industrially developed nations, however, recent studies have shown that air pollution is a growing problem in developing countries as well, and hence, attention should be paid to this evil before it is too late. (Shrestha et al., 1997). Urban air quality management strategy in Asia (Kathmandu valley report) reported that PM10 concentration is 800 µg/m3 in Kathmandu and its also mentions about the respiratory problems and impact due to pollution estimated, URBAIR (1997). Shakya (2001) found that the traffic police personnel working in the high vehicular flow areas were found to be suffering from health effects related to PM10 like throat irritation, irritation of eyes, burning sensation and excessive watering of eyes. Thapa (2001) concluded that the concentrations of pollutants (biological and non¬-biological) in the air have increased as the urbanization proceeded. More microorganisms are found in areas with more particulate matters. Shrestha (2002) reports the prevalence of respiratory illness in Kathmandu valley due to particulate matter. He also reports that the number of cases of respiratory illness has been increasing at steady rate and that monitoring of ambient air qualities carried out by various independent institutions indicates that the levels of particulate matter are also on the increase. The level of these pollutants has exceeded the standards set by EPA and WHO. Giri et al., (2004) observed that the pre monsoon and winter seasons are vulnerable to the increased level of particulates in the valley. They conclude that the guiding principle to allow the monsoon to exert its positive influence to the fullest possible extent in reduction and washing effects of particulates thereby preventing the particulate suspension in the ambient air. Different study found different concentration of PM10 with in Kathmandu valley is very high such as 197?775 µg/m3 (RONAST, 1992), 59?127 lg/m3(Karmacharya and Shrestha, 1993), 100?190 lg/m3 (ENPHO, 1999) PM10 was found to be 54-118 µg/m3 in low traffic area in dry season and 33.2-114.1µg/m3 in rainy season. Annual PM10 in high traffic area was found to be: 261.4±28.5 µg/m3 (Sapkota, B.K., 2002). According to a study conducted by Nepal Environmental and Scientific Services (NESS) in 1999, 24 hour average PM10 (Particulate Matter of size less than 10 micron) value ranges between 49 and 495 µg/m3 and average values were 225, 135 & 126 µg/m3 in core, sub-core and remote part of the valley respectively. In urban areas of Nepal PM may be generated through human activities, including diesel trucks, wood stoves and some industrial processes. Operation of brick kilns has been considered as one of the major source of air pollution in the Kathmandu Valley. Brick manufacturing by Bull''s Trench kilns was potentially a significant source of atmospheric emission (Sharma et al., 1995).

From the above discussion it can be said that most of the air pollution studies conducted in Nepal were focused on Kathmandu Valley only. Very few air pollution study were done in semi urban areas of the country. The majority of the air pollution studies focused on traffic emissions, whereas industrial, domestic and other sources of air pollutants are not seriously undertaken in Nepal. There are several Non Governmental Organizations (NGOs), government offices and institutes working in the field of air pollution. However, their activities are scattered and limited within the city areas. At this point it is need to note that, so far there were no air quality monitoring progrmme conducted in Banepa, Dhulikhel or Panauti municipalities.

OBJECTIVES:

The main objective of this study was to determine the ambient air quality data and understanding of air pollutant concentrations in suburban areas near Kathmandu, Nepal. Some of the sub objectives are to quantify some of the major criteria pollutants which would represent different areas having varied activities like industrial, commercial and residential through prescribed techniques of environmental sampling and chemical analysis, and compare pollution levels among them. It also aimed to assess the variation of pollution concentrations at different times of the day and for different seasons.

MATERIALS AND METHODS:
Site Description:

Banepa, Dhulikhel and Panauti are geographically located in the same valley region known as the Banepa valley with distances of 28 km east from Kathmandu Valley. The internal distance is no more than 7 to 8 km among the municipalities. Banepa and Dhulikhel are both situated on the Arniko Highway. This highway is Nepal''s only road to the Tibetan border and was constructed in the 1960s by the Chinese. It is an important trade route for goods coming from China into Nepal. Panauti is attainable from the Arniko Highway in Banepa over a seven kilometer long side street. The study comprised of air monitoring during the day time at three municipalities of Banepa, Dhulikhel and Panauti. In each of the Municipalities three air monitoring stations were established representing Industrial, Commercial and Residential areas. So there were altogether 9 air sampling stations selected in Banepa Valley.

Principle of Air Sampling:

Sampling by definition is simply taking a known volume of air through a filter medium that is normally a filter paper where the contaminant is captured. A volume of air and an amount of pollutant will give a result as a concentration of the contaminant, expressed as either micrograms per cubic meter (µg/m3). The volume of airflow (m3) can be calculated by multiplying the flow rate of air (liter/min) through the filter medium with the time (minutes) and by dividing with 1000 (to covert air volume into m3). The concentration (µg/m3) of pollutant was calculated by dividing the actual weight of contaminant (µg) by volume of airflow (m3). TWA (Time Weighted Average) was followed in the present study. The three basic ingredients of air sampling were noted: Amount of pollutant collected, Flow of air through the filter medium and Total time of air sampling in minutes.


Sampling Time and Frequency:

Ambient air pollution levels may be influenced depending upon different variables like time in a day, week day and holiday, Seasonal variation, Location, Pre dominant land use in the area etc. These confounding variables make the investigation more perplexed and difficult to ascertain in a conclusion. Therefore, this sampling design normalized the samples, taking into account similar kind of variables of similar type and nature in the study area. PM10 has been estimated from air sampling programme which spanned 7 months and a total of 63 days. The samples were collected once in a month for each of the nine sites. Every day two sample were collected in the morning and evening. So the total number of sample was 126. The total sampling time was 8 hours in a day. These 8 hours in a day were divided into 4 hours each covering pick hours of day 9am to 5pm. So actual period of high traffic concentration of pollutants was measured.

Pre-field Arrangement:

47 mm diameter GF/A filter papers discs were stored in a controlled environment to equilibrate (such as desiccators) at 25 degrees C and RH less than 35% for at least 24 hours. After desiccation, the filter papers were pre-weighed for three times to obtain concurrent weight. Filter-holder cassette assembly: The cap of filter paper holder was removed, freshly pre-weighed filter paper was assembled in the filter paper holder cassette of APM 550 Fine Particulate Sampler and cap was carefully closed.

Field Arrangement:

Envirotech APM 550 Fine Particle Sampler was used for estimation of the PM10. For sampling the PM10 fraction of SPM the WINS Impactor must be removed from the air stream. Followed the steps given below to set up the system:
*Gently remove the Air Inlet and PM10 Impactor assembly mounted at the top of the APM 550 Sampler.
*Open the Sampler door remove the down tube mounted on top of the WINS Impactor.
*With a firm upward thrust loosen and remove the WINS Impactor assembly.
*Mount the spare (longer) down tube directly over the cover unit of the filter holder.
*Place the air Inlet and PM10 Impactor assembly on top of the down tube.
*APM 550 system is now configured for sampling PM10 Particulates in ambient air. Installation at the site: The vacuum pump of the APM 550 Fine Particulate Sampler was kept on a flat platform and the Filter-holder cassette (Cone) was fixed 5 to 30 meter above the ground level.
*The pump was work on, flow of air measured from gas flow meter and the time of starting the sampler was noted down in the air sampling data sheet. The entire processes of air sampling were closely observed and ensure that equipment worked well all the sampling time.

Calculation:

Weight of the filter paper before monitoring = W1 grams
Weight of the filter paper after monitoring = W2 grams
Weight of particulate matter collected = (W2-W1) = W grams
Flow rate of the LVS air sampler (maintained) {Q} = 25 liter per minutes (LPM)
Total time of sampling = T (minutes)
Total volume of air sampled = (Q x T) ÷1000 = V (m3)
Reporting Concentration of Particulate matter = PM (µg/m3) = W÷Vx106

RESULTS AND DISCUSSION:

Mean concentration of PM10 in Banepa Municipality:

In all 42 days of air monitoring reflected all the three seasons (winter, pre-monsoon and monsoon) that was conducted at Banepa. The findings suggest that during winter season the PM10 was more and among areas Banepa Industrial area noted highest PM10 level. In fact, at Industrial area a maximal level of 510.23 µg/m3 has been recorded on one occasion which was not very much deviant to the mean level indicating persistently higher levels of PM10 in this area. The seasonal trend in PM10 levels showed that Winter > Pre-monsoon > Monsoon. The trend noted among the areas was Commercial > Industrial > Residential on almost all the occasions excepting the picture at winter season between Commercial and industrial area. The over all mean, standard deviation, minimum and maximum level of PM10 in Banepa was respectively 224.33 µg/m3, 94.66 µg/m3, 82.55 µg/m3 and 510.23 µg/m3.

The National Ambient Air Quality Standards (NAAQS) in Nepal for PM10 had been set as 120 µg/m3 which is 24 hourly values (MOPE, 2005). From the study it was seen that the concentration of mean PM10 pollution in all three season in all the three land use areas of Banepa had crossed the NAAQS level except Banepa Industrial area and Banepa Residential area in monsoon season. But, it is noted that the present study represented 8 hourly values which were reflected only the pick hours concentration of PM10 in the studied areas. In Nepal, Ministry of Population and Environment (MOPE), has categorized five different types of air quality categories based on levels of PM10. The categories prescribed are range 0-60µg/m3 as "Good", 60-120µg/m3 as "Moderate", 121-350µg/m3 as "Unhealthy", 351- 425µg/m3 as "Very Unhealthy", and >425µg/m3 as "Hazardous". The same categories have been maintained for the purposes of interpretation statistical analysis in this study. The number of occasions on which the particulate concentration values have exceeded these prescribed cut off points is considered as a measure of pollution level. In Banepa most of the observations were under Unhealthy category (121-350µg/m3). In these monitoring stations in Banepa a few observations even exceeded very unhealthy category (351- 425µg/m3).

Mean concentration of PM10 in Dhulikhel Municipality:

In all 21 days of air monitoring reflecting all the three seasons that was conducted at Dhulikhel Municipality. From the study it was found that during winter season the mean PM10 concentration was more and among the areas Industrial area in Dhulikhel noted highest mean PM10 concentration. In the commercial area a maximal level of 399.27µg/m3 has been recorded on one occasion, which was highest within the areas. The seasonal trend in mean PM10 levels showed that Winter > Pre-monsoon > Monsoon. Among the areas the trend noted Commercial > Residential > Industrial on almost all the occasions excepting the picture at pre-monsoon season where the scenario is Commercial > Industrial > Residential. The over all mean, standard deviation, minimum and maximum level of PM10 in Dhulikhel Municipality''s was respectively 170.61µg/m3, 76.43 µg/m3, 68.36 µg/m3 and 399.275 µg/m3.

From the study, it was also seen that the concentration of mean PM10 pollution in all three season in all the three land-use areas of Dhulikhel Municipality had crossed the NAAQS level of 120 µg/m3 except Dhulikhel Industrial area and Dhulikhel Residential area in monsoon season. These findings conclude that, in Dhulikhel commercial area is more defined and is associated with higher PM10 concentration compared to industrial area. It is evident monsoon had a washing effect of particulates from the atmosphere and hence the particulates restrictively get airborne.

Mean concentration of PM10 in Panauti Municipality:

In all 21 days of air monitoring reflecting all the three seasons that was conducted at Panauti. The study found that during winter season the PM10 concentration was more and among the areas Commercial area in Panauti noted highest mean PM10 concentration but in Panauti Industrial location a maximal level of 364.57µg/m3 has been recorded on one occasion, which was also highest within the areas as well as in all seasons. The seasonal trend in PM10 levels show that Winter > Pre-monsoon > Monsoon. The trend noted among the areas was Commercial > Industrial > Residential in all the occasions. The over all mean, standard deviation, minimum and maximum level of PM10 in Panauti Municipality''s was respectively 169.11µg/m3, 79.72µg/m3, 56.31µg/m3 and 364.57µg/m3.

From the study it was also seen that, the concentration of mean PM10 pollution in all three season in all the three land use areas of Panauti had crossed the NAAQS level of 120 µg/m3 except Panauti Industrial area in monsoon season and Panauti Residential area in pre-monsoon and monsoon seasons. This finding suggests that, in Panauti commercial area is more defined and is associated with higher PM10 concentration compared to industrial and residential areas. It is clear monsoon has a washing effect of particulates from the atmosphere and therefore the particulates restrictively get airborne.

PM10 concentration in Sites in respect to Seasons:

The study shows that, Banepa Commercial area has the highest seasonal mean PM10 concentration with mean concentration of 247.18µg/m3 among all the 9 sites of 3 municipalities. It recorded second highest level of mean PM10 concentration in winter and highest in pre-monsoon season. In winter Banepa Industrial area had highest concentration with a mean level of 363.70µg/m3. In monsoon Dhulikhel Commercial area had highest concentration with a mean concentration of 200.66µg/m3. At this point it is need to note that the reason behind the high concentration of PM10 in Dhulikhel Commercial area in monsoon season was the cutting effect of hill near the Bus Park to build the new bus park during the month of June and July. The chronology of the highest to lowest pollutant area in all three municipalities was as Banepa Commercial>Dhulikhel Commercial >Banepa Industrial>Panauti Commercial>Banepa Residential>Panauti Industrial>Dhulikhel Residential >Dhulikhel Industrial >Panauti Residential.

CONCLUSION:

This preliminary investigation deal with the seasonal PM10 concentration in all three municipalities of Kavre district of Nepal according. It represent the mean concentration, Standard deviation, maximum and minimum concentration of all nine sites. Commercial areas in even in small towns of Nepal observed with high PM10 levels. PM10 levels had definitive trend at all the 3 sub-urban areas, like commercial> industrial> residential. Monsoon season was observed less concentration of PM10 in all the areas. The study provided base line data on air quality in terms of PM10 concentration that provided in representative semi urban areas of Nepal. The study clearly indicates that the proportion of respirable particulate concentration is very high and there is an imminent health risk with respect to the particulate pollution in the study area. Environmental legislation and regulations for pollution control are weak as are their implementation. The contemporary Acts and Regulation dealing to abate air pollution sources is not only very superficial but also lack of comprehensiveness visa versa coordination. Both Nepal Standard Act and Environment Protection Regulation are seeking to control air pollution by means of command and control approaches. But further working modalities are yet to publish (Devkota, 1999).There is no coherent legislative framework to control air pollution. Rather air pollution control is spread over various Acts. Moreover, regulations that govern the enforcement of laws have to be developed.

ACKNOWLEDGMENTS:

This paper was presented in the 10th Pacific Regional Science Conference organized by Bangladesh Regional Science Association (BRSA)Summer Institute during 15-17 May 2008, at Dhaka, Bangladesh. The authors are thankful to the organizers of the Conference. The authors are also thankful to Dr. Roshan Man Bajracharya, Associate Professor who provided useful suggestion through out the research. Authors are indebted to Rinu Karmacharya, Silu Bhochhibhoya, Gyanendra Chaudhary and Rabi Wenju, post graduate students of department of environmental science and engineering of Kathmandu University for their help during this research. Grateful thanks to department of environmental science and engineering of Kathmandu University for providing the equipments. Sincere thanks to the administration of Kathmandu University for their support to carryout the study.

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Ahmad Kamruzzaman Majumder*, Dr. V. Krishna Murthy,
Dr. Sanjay Nath Khanal and Dhiraj Giri
Department of Environmental Science and Engineering,
School of Science, Kathmandu University, P.O. BOX 6250, Dhulikhel, Nepal.
Phone: [phone]
Corresponding authors Email: [e-mail], [e-mail]