Advances in Applied Science Research Open Access

Keywords

Horticulture; Nauni; Air Quality Index; Air pollution

Introduction

Air pollution is now a serious worldwide public health problem. Developmental activities like industrial expansion, mining exploration, transportation and constructional works etc. cause degradation and drastic changes in every component of environment. Air pollution has emerged in the past few decades as the most crucial problem to mankind and a large number of studies in this regard have been undertaken in all over the World [1]. Clean, pollution-free and hygienic living surroundings are essential as they are directly related to human health and better living standard of the country [2]. Naturally, the sources of pollutants are volcanic eruptions, forest fires and dust storms whereas, anthropogenic source of pollutants comes from burning fossil fuels, industrial and vehicular emissions, power plants, mining, drilling and construction of roads [3]. Sulphur dioxide, nitrogen dioxide and suspended particulate matter are regarded as major pollutants in India. The effect of particulates depends on its shape, size, concentration and time of exposure in relation to its mass and composition [4]. About 60 percent of air pollution in Indian cities is due to automobile exhaust emission. The vehicular emission contains more than 450 different organic chemical compounds either in gaseous or in particulate or in the combined forms. The emission loads in Indian urban cities are in the range of thousands of tons per day. Among air pollutants, particulate matter (PM) is a ubiquitous and it is especially a major problem due to its adverse health effect, visibility reduction and soiling of buildings [5].

Ambient air quality refers to the quality of outdoor air in our surrounding environment. It is typically measured near ground level, away from direct sources of pollution. There are many factors that affect air quality, making the search for clean air quite a complicated issue [6]. Air quality is a scale reporting the air pollution. It transforms weighted values of individual air pollution related parameters (e.g. SO₂, CO, visibility, etc.) into a single number or set of numbers and is widely used for air quality communication and decision making in many countries. The objective of an AQI is to quickly disseminate air quality information (almost in real-time) that entails the system to account for pollutants which have short-term impact [7].

Awareness of daily levels of air pollution is important to the citizens, especially for those who suffer from illness caused by exposure to air pollution. AQI is a tool, introduced by Environmental Protection Agency (EPA) in United States of America (USA) to measure the levels of pollution due to major air pollutants. In India, National Ambient Air Quality Standards (NAAQS) are the standards for ambient air quality set by the Central Pollution Control Board (CPCB) that is applicable nationwide. The CPCB has conferred this power by the Air (Prevention and Control of Pollution) Act, 1981.

Materials and Methods

Study area

The University is located at Nauni which is 13 km from Solan town. It is situated at the height of 1260 meters above mean sea level at 30°51’53”N latitude and 77°10’8”E longitude (Figure 1).

Figure 1: Satellite image of the study area.

The main campus experiences all three seasons viz. summer, monsoon and monsoon. The University has five buses which services daily from Solan city to the University campus. In addition to this, 200-250 vehicles enter the campus premises daily. With development and increase in the number of students and staff, more activities have been going on and increase in number of vehicles and their frequent use has resulted in increase in pollution of air in the campus. Students and staff come from Solan daily in University buses and private vehicles that resulted in increased vehicular emission. The University is also frequently visited by farmers and students for workshops and field visits. On top of that, the University has a scenic beauty, thus people come over to enjoy this beauty which further aggravated the problems of pollution. Also, the campus encounters peculiar weather as it is surrounded by hills on all the sides, which restricts the transport and dispersion of the pollutants.

Sampling method and analysis procedure

The study was conducted at the University campus during the year 2017 by selecting four sites namely traffic, residential, farming and forest (control). To study the effect of seasons on the ambient air quality, three seasons viz. summer (April-May), monsoon (July-August) and autumn (October-November) were considered. The data was recorded for eight hours at each site during day time. In each of the site, three locations were selected as replications to minimise error. The sampling was carried out using two instruments viz. Respirable dust sampler (Cat. No MBLRDS-002) and Environmental Perimeter Air Station (EPAS).

Sulphur dioxide has been analysed by modified West and Gaeke Method IS 5182, part II; Nittrogen dioxide by modified West and Gaeke Method IS 5182, part II and particulate matter (RSPM and NRSPM) by Gravimetric method IS 5182 part IV. TSPM concentration has been calculated by summing up the two. For measuring the concentration of VOCs in the ambient air, the digitalized Environmental Perimeter Air Station (EPAS) was used.

Air quality index

The quality of air in the study area had been estimated from the air quality index. The air quality index had been calculated from the observed SPM, PM₁₀, NO₂ and SO₂ values using the formula.

AQI = 1/4× (I_PM10 / S_PM10 + I_SPM / S_SPM + I_SO2/ S_SO2 + I_NOₓ / S_NOₓ) × 100

Where,

I_PM10, I_SPM, I_SO2 and I_NOₓ are individual values of respirable particulate matter, sulphur dioxide, oxides of nitrogen and suspended particulate matter, respectively.

S_PM10, S_SPM, S_SO2 and S_NOₓ are the standards of ambient air quality.

Results and Discussion

The concentration of pollutants during various seasons in study at different locations was given in Tables 1-3. Site-wise variation of the air quality parameters in the University campus showed that there was a similar trend on the concentration of the pollutants at the selected sites. For all the air quality parameters considered, the concentrations at the sites showed a decreasing trend of traffic > residential > farming > forest. Seasonal variation of the air quality parameters in the University campus also showed a similar trend. The concentration of the pollutants during the seasons was in the order of autumn > summer > monsoon.

Table 1: Concentration of pollutants (µg/cu-m) at University Campus during Summer, 2017.

Table 2: Concentration of pollutants (µg/cu-m) at University Campus during Monsoon, 2017.

Table 3: Concentration of pollutants (µg/cu-m) at University Campus during Autumn, 2017.

Table 4 shows the values of Air Quality Index calculated from the data of different seasons for the ambient air quality of the University campus during 2017. The highest AQI value of 90.60 was observed during autumn season at traffic site followed by 81.80 and 61.55 at the same site during summer and monsoon respectively. The lowest AQI value of 9.2 was observed during monsoon season at forest (control) site followed by 11.07 and 14.73 at the same site during summer and autumn. As a whole, autumn season showed the highest AQI values at all the study sites while the monsoon season showed the lowest AQI value.

Table 4: Air Quality Index of the University Campus.

The different rating scales of AQI are depicted in Table 5. The AQI scale is divided into six categories as given in the table. The higher the AQI value, greater is the level of pollution and so is the risk.

Table 5: Rating scale of AQI values.

Figure 2 shows the AQI trends of the sites in the three seasons (summer, monsoon and autumn) during the study. The best air quality was found during monsoon season at all the sites whereas autumn season showed the lowest air quality. Monsoon season in the campus received a greater amount of rainfall which resulted into washing out of the air pollutants thus exhibiting the best air quality. The relatively lower air quality was shown during autumn season because of the calm atmospheric conditions which resulted into less dispersion of air pollutants away from the campus.

Figure 2: Seasonal variation of AQI at different sites during the study period.

Conclusion

The study inferred that the concentrations of all the air quality parameters were within the permissible limits in the University campus. The AQI in the campus ranged from ‘good’ to ‘moderate’ during the three seasons in study. The seasons of the year also have impact on the air quality. Monsoon season showed the best air quality in terms of AQI while autumn season showed the highest AQI. The traffic site has the highest concentration of the pollutants and also showed a moderate air quality index during summer, monsoon and autumn season while residential, farming and forest sites showed a good air quality.

Conflict of Interest

There is no conflict of interest regarding the publication of this paper.

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