1. Introduction

Air Pollution has a major impact on the physical & mental well being of urban residents worldwide. The air pollutants get entry in the human body through inhalation. They damage the respiratory system and interfere with the natural metabolic and other activities of human body. Due to damage of respiratory system various “Pulmonary Function Values” are reduced. The present study is conducted at Jodhpur City to assess the reduction of Forced Vital Capacity of residents due to ambient air pollution. FVC is the volume of air a person exhales with forceful expiration after maximal inspiration. Normally it is reached within 3-4 seconds but airway obstruction prolongs this time ^[6].

The ‘Surya Nagari’ Jodhpur is the second largest city of Rajasthan (India) and the Gateway of famous ‘Thar Desert’ inhabitating a population of 8, 56,034 according to 2001 census. Jodhpur is situated on northwestern border of Rajasthan. The increased Army/Air Force, Industrial, Trade & Commerce and Tourism activities have led to expansion and growth of the city and other related economic activities up to a great extent. Although there are more than 100 pollutants, which are broadly classified into two categories which are Particulate Matter and Gases. Here we are concerned with few important pollutants like Respirable Suspended Particulate Matter (PM₁₀), SO₂, and NO₂ only. Many environmental cum medical studies have been carried out worldwide to establish a link between different type of pollutants, respiratory diseases and level of pollution that would significantly affect human health. The acute health effect of suspended particulate matter (SPM), even at short term low levels exposure; include increased daily mortality and hospital admission rates for exacerbation of respiratory disease ^[5]. Long term exposure to PM_2.5 increases the risk of the non-accidental mortality. Living close to busy traffic appears to be associated with elevated risk ^[2]. The available human clinical results do not establish a mechanistic pathway leading to adverse health impacts for short term NO2 exposure at present day ambient environment ^[3]. In all the analytical studies total mortality was directly associated with long term exposure to particulate matter ^[4]. Each day our lungs are directly exposed to more than 7000 liters of air, which contain varying amount of inorganic, organic particles and various types of gases. Hence it is required to assess the damage on the basis of air quality of the area. In this case study, relationship between severity of the damage (in terms of reduction in lung capacity) & exposure duration and concentration of pollutants (in terms of Air Quality Index) has been established.

2. Methods and Methodology of Case Study

As per EPA guidelines concept of Air Quality Index (AQI) has been adopted. The AQI of different locations of Jodhpur has been determined to select the various spots for study. On these particular spots the most affected persons were selected for the study on the basis of their continuous exposure. The respiratory parameter considered in the study was Forced Vital Capacity (FVC) and it was measured with the help of computerized Spirometer. Fine Particulate Sampler and High Volume Sampler were used in this study to measure the concentration of various pollutants considered in study. AQI was determined on the basis of concentration of pollutants.

Various observations for SO₂, NO₂ and PM₁₀ were taken at selected locations of Jodhpur. Amongst them the following four sites were selected as shown in Table 1 whose annual mean values were highest.

From these concentrations of the pollutants, value of sub-indexes of respective pollutants was calculated to predict AQI. The formulae for sub-indexes calculation are depending on the range of concentration of respective pollutant and are given in Table 2.

The highest value of sub-indexes for various pollutants for that sampling station is considered as AQI for that particular sampling station and is given in Table 3.

Table 1. Annual Mean values of pollutants measured at various sampling stations

Download as

PowerPoint Slide

Larger image(png format)

Tables index

Veiw figure

View current table in a new window

View next table

Table 2. Formulae used for sub-index calculation at different concentration of pollutant [1]

Download as

PowerPoint Slide

Larger image(png format)

Tables index

Veiw figure

View current table in a new window

View previous table

View next table

Table 3. AQI value at different sampling station

Download as

PowerPoint Slide

Larger image(png format)

Tables index

Veiw figure

View current table in a new window

View previous table

View next table

After determination of AQI the exposed persons were selected at different point for determining the reduction in FVC. The selection of persons was based on exposure duration (1 to 5 years of exposure, minimum exposure 8 hours or more each day). Persons having hereditary/ previous respiratory diseases, smoking habits, chewing of tobacco & alcoholic etc. were not taken for study. The control population were selected who were not exposed /little exposed to such environment for comparison purpose.

The Pulmonary function parameter FVC was measured for all the selected persons. The study subjects were divided in various categories depending upon their exposure duration. The predicted values of FVC, is calculated by using ERS-93 equation. Predicted values are designated as FVC_P. The age (A), height (H) and weight of every person were recorded for the calculation of predicted value of FVC.

For Males (> 18 years):

(1)

Index is developed to find out the extent of damage and percentage of volume reduction in fraction. This Index is designated as IFVC which is calculated with the help of following formulae:

(2)

The Pulmonary function parameter FVC was measured for different persons for their different exposure duration at all sampling station. Numbers of observations for different exposure duration and for different AQI are given in Table 4 and Table 5. Mean values of IFVC (Index that represent extent of damage) is calculated for each case and is given in Table 4 and Table 5.

For the controlled population (population which was not exposed to urban pollution but belongs to same class of society) total 38 numbers of observations was taken and mean value of IFVC was calculated and which was found to be 0.037.

Table 4. Mean Values of IFVC for 1, 2 & 3 years exposure

Download as

PowerPoint Slide

Larger image(png format)

Tables index

Veiw figure

View current table in a new window

View previous table

View next table

Table 5. Mean Values of IFVC for 4 and 5 years exposure

Download as

PowerPoint Slide

Larger image(png format)

Tables index

Veiw figure

View current table in a new window

View previous table

View next table

Data shows the increasing trend for all the cases, which is not truly linear but most appropriate relation to represent this increasing trend is linear only. Hence the multi – linear Regression analysis is done for IFVC and significance tests are applied to verify the consistency & significance of all the parameters of the multiple regression models as under:

Table 6. Model summary

Download as

PowerPoint Slide

Larger image(png format)

Tables index

Veiw figure

View current table in a new window

View previous table

View next table

‘R’ is multiple co-relation coefficients. As the value of R is positive (from ANOVA Table) it is a positive co-relation. ‘R2’ is coefficient of determination whose value is 0.979. It indicates that two independent variables Exposure Duration (EXDUR) and Air quality index (AQI) jointly account for the variation in IFVC up to 97.9% and remaining 2.1% variation is due to other reasons.

Table 7. ANOVA ^{(Dependent Variable: IFVC)}

Download as

PowerPoint Slide

Larger image(png format)

Tables index

Veiw figure

View current table in a new window

View previous table

View next table

Where, d.f. is ‘degree of freedom’, and F is ‘Ratio of Mean Squares’

ANOVA Table 7 gives the value of calculated value of F_calculated.(i.e. F=305) and critical value of F from standard tables (i.e. F_{k, n – k l,α}=3.59).

Here, F_calculated > F _{k, n-k-l, α}, Hence, reject H₀ at α (= 0.05) level of significance, therefore significance of individual β’s be tested by‘t - test’.

Table 8. Coefficients ^{(Predictors: (Constant), AQI, and EXDUR)}

Download as

PowerPoint Slide

Larger image(png format)

Tables index

Veiw figure

View current table in a new window

View previous table

Where, Std. Error is ‘Square root of ratio of Sum of Squares to Category of Samples’ and t is ‘ratio of Parameters difference (calculated value minus value from std. tables) to Standard error’.

Here t > t_{n – k – 1; α /2}; therefore reject H₀ (Hence, β₁≠ 0 and β_{2 ≠ 0}). As the estimated b₀, b₁ and b₂ are b₀ = -0.197, b₁ = 0.053 and b₂ = 0.003, hence finally estimated multiple regression equation for IFVC that relate the severity of damage to the exposure duration and air quality index can be expressed as:

Where

Y_{F =} IFVC

X₁ = Exposure duration

X₂ = Air Quality Index

3. Conclusion

The quality of air in Jodhpur is worsening day by day due to increase of air pollutants concentration. Although the level AQI which is recorded as ‘Moderate’ (AQI < 100) but reduction in forced vital capacity of lungs for exposure duration of 5 years is significant. Data indicated that as the Exposure Duration increases the percentage reduction in forced vital capacity of lungs increases. It also shows that the value of AQI index increases the reduction of forced vital capacity of lungs increases. It is revealed from the study that exposure duration and air quality both is responsible for reduction of vital capacity of lungs. The significant reduction in IFVC is due to air pollutants because the reduction is negligible in control population. It reflects that the ‘Forced Vital Capacity’ of lungs decrease as the Exposure Duration increases as well as the pollutants concentration increases.

The estimated multiple regression equations directly gives relationship between decrease in vital capacity of lungs, exposure duration and air quality index.

The calculated values of ‘Y_F’ give direct indication of damage severity without any medical or Pulmonary Function Test. The values y_F will be in between 0 to 1, if the value is more, this means the damage intensity is very high. Hence from the developed equation, reduction in vital capacity of lungs can be calculated.

References

[1]	Azman Z.A., Lay L.T., Fadzillah, O. & Haslina, M. (1994) ‘A Proposed Air Quality Index for Malaysia’, Serdang: University Pertanian, Malaysia
	In article
[2]	Chen H, Goldberg MS, Villeneuve PJ. “ A systematic review of the relation between long term exposure to ambient air pollution and chronic diseases”.Rev Environ Health, 2008 Oct-Dec; 23(4)243-97.
	In article		PubMed
[3]	Hesterberg TW et al. “Critical review of human data on short term nitrogen dioxide exposure:evidence for NO2 non-effect levels”. Crit Rev Toxicol (2009); 39(9); 743-81.
	In article		CrossRef PubMed
[4]	Pelucchi C et al. “Long term particulate matter exposure and mortality: a review of European epidemiological studies” BMC Public Health, 2009 Dec8; 9: 453.
	In article		CrossRef PubMed
[5]	Schwela D. “Air pollution and health in urban areas”. Rev Environ Health. 2000Jan-Jun; 15(1-2):13-42.
	In article		CrossRef PubMed
[6]	User manual (1999), ‘RMS Medspiror’, Recorders & Medicare System, (European Respiratory Society, ERS-93) 181/5 Phase I, Industrial Area, Chandigarh (India).
	In article