An Analysis of GRAP Task Force Directions for Improved AQI in Delhi during 2018

Air quality has been a matter of public concern in Delhi. The concentration of Particulate Matters (PM2.5 and PM10) often surpasses the Indian National Ambient Air Quality Standards (NAAQS). This study is focused upon the evaluation of Environment Pollution (Prevention and Control) Authority (EPCAs) Graded Response Action Plan (GRAP) action during 2018 in terms of PM2.5 and NO2. In order to control air pollution sources in National Capital Region (NCR), the (EPCA) Environmental Pollution (Prevention and Control) Authority directed GRAP to advise the local industries and other sources of pollution to close their operations on particular dates whenever Air Quality Index (AQI) showed severe level. In this study, we have analyzed 24 hourly averaged Air Quality Index (AQI) data for the period September 2017 - January 2018 and September 2018 - January 2019 at two sites i.e. Delhi Technical University (DTU) and Income Tax Office (ITO) respectively. The GRAP results showed a significant decrease in AQI values of both after every order passed by GRAP task force. In general, the PM2.5 AQI values were always higher during year 2017-18 as compared to 2018-19 at both sites.


Introduction Air Quality Standards
The issue of air quality in the National Capital. Region (NCR) Delhi is a matter of public concern. Poor air quality has various harmful effects on the environment and human health causing smog, acid rain, reduced visibility and increasing premature deaths, asthma attacks and chronic respiratory illness. 1,2,3 In general, the poor air quality of Delhi is due to high concentration, of the PM 2.5 and PM 10 which have been reported violating the limits of National Ambient Air Quality Standards (NAAQS). 4,5 The soil dust, road dust, and construction site dust contribute to the high loadings of particulates in this region 6,7 other sources such as local industries, automobiles, vehicles, generator sets; brick kilns etc are also responsible for the contribution of air pollutants. 8,9 The burning of crop residues in neighboring states also adversely affects the air quality of Delhi region during post-monsoon season. 10 In the NCR, among other pollutants, it has been reported that the PM 2.5 has greater potential on health effects and respiratory system than the corresponding particles PM 10 . 11,12 In the guideline of the World Health Organization (WHO) and the NAAQS under the USEPA, the recommended levels for PM 2.5 and PM 10 based on 24 hourly and annual observations have already been mentioned. Several studies have considered these levels as baseline, where results have been provided by making comparison with respect to the prescribed level only. However, the need of chemical speciation of PM 2.5 has also been emphasized in order to differentiate its natural vs anthropogenic constituents. 13 Other important pollutant is NO 2 which has been reported with increasing trends in Delhi. 14,15,16 According to reports, the levels of NO 2 are increased, primarily because of number of vehicles are increased drastically. 6 The number of vehicles is increased from 24, 32,295 in 1994 to 80, 52,508 in 2014 6 and further 10 million vehicles till March 2018. 17 The increase in NO 2 levels affects human health, acid deposition and ozone chemistry. 18 NO 2 is contributed by the combustion sources such as industrial and automobiles etc. 19,20 NO 2 causes respiratory health effects; NO 2 also has an important role in tropospheric ozone and smog formation .21,22 Due to increase in NO 2 , NO 3 concentration in rain water has been reported 11 times higher in 2011 as compare to 1994. 23 In Indian context, the Central Pollution Control Board (CPCB, Govt. of India) has been monitoring the daily air quality and several stations which have been mandated to the monitoring purpose as well. The Indian NAAQS (under the CPCB) have already been established the prescribed levels of major air pollutants in ambient environment. 24 In the CPCB notification 2009, NAAQS limits have been prescribed for these pollutants under two categories i.e. i) industrial/ residential area and ii) ecologically sensitive areas. In general, the government has taken several measures or air pollution mitigation to improve the air quality of Delhi including the introduction of unleaded petrol, phasing out old commercial vehicles, low sulphur diesel; compressed natural gas (CNG) based vehicles etc. Other such efforts include implementation of Bharat stage-IV (BS-IV), phasing out 15 year old vehicles, ambient air fund, prohibiting burning of leaves and plastics in open, promotion of gas based thermal power plants, restriction on diesel trucks, ban on petcocks, ban on diesel generator sets etc. 9,25 The very popular mitigation step has been Odd-Even rule introduced by government of Delhi two times, first time during 1 st January to 15 th January 2016. The second round of Odd-Even was implemented during 15 th April to 30 th April 2016. All These odd even campaigns could not bring the required quality of air. However, due to less number of vehicles plying on roads, the running time was saved. Also, these campaigns were able to mobilize and encash the sentiments of people and probably, could reflect the proactivness of the government. 25

Graded Response Action Plan (GRAP)
In order to reduce air pollution in Delhi-National Capital Region (NCR), Graded Response Action Plan (GRAP) was introduced recently directed guided by the Environment Pollution Control Authority (EPCA). Various agencies such as CPCB, the Civic Agencies and Urban Development Department, Transport Department, Pollution Control Committee of Delhi and Traffic Police are responsible to implement the plan. 17 The task Force on Graded Response Action Plan (GRAP) holds meetings frequently. The recommended actions to be implemented in the field accordingly. Last year GRAP task force has conducted several meetings between November 2018 and January 2019 and directed for taking action. The GRAP has been notified by government for Delhi-NCR which comprises measures such as restriction on entry of trucks into Delhi; ban on construction activities, introduction of odd-even scheme for vehicles, closure of schools during severe condition, closure of brick kilns and stone crushers; ban on diesel generator sets and burning in landfills and parks. 9 The GRAP task force also ensures the enforcement of Graded Response Action Plan (GRAP) in NCR as per the pollution levels. However, stopping open burning of plastic and polythene which was source of chlorine and HCl in air, has been reported as a trigerer of ozone spikes at industrial and residential areas. 26 Though the CPCB and other networks have been calculating AQI for various pollutants, but in order to obtain a comparative scenario, only the daily and monthly AQI data for PM 2.5 and NO 2 are considered in this study for two sites i.e. Delhi Technological University (DTU) and Income Tax Office (ITO) during the period from September 2017 to January 2018 and September 2018 to January 2019. In this study we are presenting the effectiveness of GRAP and a comparison of AQI or PM 2.5 and NO 2 at both the sites. We selected PM 2.5 and NO 2 for this study, as these two criteria pollutants are the prime indicators of air quality for Delhi region. PM 2.5 levels affect our inner bronchial region, sometimes resulting in acute and chronic respiratory diseases. 27 Figure-1 shows the map of study area i.e. Delhi Technical University (DTU) and Income Tax Office (ITO).

Fig. 1: Map showing the DTU and ITO sites in Delhi.
The hourly AQI data for the selected period were downloaded from the website of Central Pollution Control Board, India. 28 There are over 38 total sampling sites in Delhi out of which 24 sites are monitored by DPCC, 6 by IMD and the remaining 8 sites are monitored by CPCB. Among eight sampling sites which are, monitored by CPCB, i.e. DTU and ITO were selected for the present analysis because of their specific urban characteristics. The DTU site is located in an industrial area while the ITO site is located at a very heavy traffic junction. The monitoring protocol of the network as given on CPCB portal (cpcb.nic.in) records 8 pollutants (PM 2.5 , PM 10 , SO 2 , NO-NO 2 -NO x , NH 3, CO, O 3, and BTEX), but we selected PM 2.5 and NO 2 for this study, as these two criteria pollutants are the prime air quality indicators for Delhi air.
The measurements of PM 2.5 and NO 2 along with other parameters are carried out by online analyzers. The principle of measuring PM 2.5 is based on β-ray attenuation technique through which continuous measurement of ambient particulate matters can be obtained. The, particulate matter is sampled through the inlet of the instrument and is collected on the fiberglass filter tape. The β-ray radiation value is measured by scintillation/G.M. counter before and after sampling. Internal microprocessor handles all sequences and automatically calculates the concentration of PM 2.5 (cpcb.nic.in). NO 2 measurements are carried out by using NO X analyzer which is based on chemiluminiscence is based on. The NO 2 sampler consists of 10 ports manifold and fitted with suction pump to draw ambient air and moisture removal system. SINGH & KULSHRESTHA, Curr. World Environ., Vol. 15(1) 29-41 (2020)

Data Analysis Method
The downloaded hourly datasets were reformatted after which daily and monthly averaged values were computed using Microsoft excel. Descriptive statistics was applied to daily and monthly average datasets in order to determine the nature of variations and trends. It is pertinent to mention here that the descriptive statistics is useful to assess the central tendency (mean, mode etc.) and variability of the given dataset. Special attention was given to capture the variation pattern of AQI before and after GRAP (Graded Response Action Plan) orders. The variations of AQI values of the selected pollutants were shown using area graph and descriptive statistics. Date for the period of Sep-2017 to Jan-2018 (Non GRAP period i.e. 153 days of these 5 months) and Sep-2018 to Jan-2019 (GRAP period i.e. 153 days of these 5 months) of study parameters (PM 2.5 and NO 2 ) at various selected study sites were considered for the present study. The missing and outlier values of the downloaded datasets of pollutants were ignored and remaining data points were subjected to analysis. Table 1 gives details of GRAP task force meetings and the AQI values after the directed actions. The results showed that after the suggested actions, the AQI values reduced noticeably falling under moderate and satisfactory categories. In November 2018, EPCA conducted two Meetings on 12 and 14 November 2018 when AQI was very high under severe condition. Hence, GRAP came into an action to laid down the rules for traffic, constructions and industries for air pollution control. In response to the strict implementation of GRAP by the EPCA, significant improvement was seen in AQI. Figure-2 shows that how the values of AQI were decreased after every GRAP task force task force meeting at both the study sites. At ITO site, data of 12 November 2018 was not available for both criteria pollutants as shown in Table 1. But during remaining six dates, pollution level was noticed decreasing indicating that GRAP actions were successfully working.

AQI of NO 2
The patterns of NO 2 were very much different than PM 2.5 accordingly (Fig. 5)

ITO Site AQI of PM 2.5
The AQI values at ITO site indicated that PM 2.5 was very high during all the months except during month of December 2018. In December 2018, the AQI value was not very different from 2017 December. In December 2017, there was a small decrease in the average AQI value of PM 2.5 which was 341. While in December 2018, the average AQI recorded was 371. Fig. 6 shows that during winter months i.e. December and January for 2017-18 and 2018-19, the AQI values were almost similar because of atmospheric conditions such as temperature inversion etc. which can trap the pollutants near the surface of earth, low wind speed due to which dispersion of pollutants is not possible, and dimming of sun light effect the conversion of various oxides. In general, SO 2 and NO 2 are considered major gases contributing towards PM 2.5 or finer ranged particles but the SO 2 levels in Delhi region are very low. With respect to NAAQS reason is probably the SO 2 is adsorbed onto calcium carbonate rich dust particles forming calcium sulphate in coarse mode. 30 Due to this reason PM 2.5 contributed by    As given in Table 4, every time there was a decrease in percent relative difference between 6.0 and 47.3 at DTU site and between 8.8 and 45.7 at ITO site. in 2018-19 which might be due conducive atmospheric conditions.
On the other hand, the monthly average relative difference of NO 2 was very different from PM 2.5 values. The relative difference was noticed between -7.2 to 240.5 at DTU while -32.1 to 90.1 at ITO site. The decrease in AQI was seen during winter months of 2018 as compared to 2017 with few exceptions.

Conclusion
The GRAP task force action plan was very effective during the days when pollution level entered into the severe category. GRAP task force immediately came into action and conducted meetings to mitigate the heavy loadings of pollution in NCR Delhi. In this study we noticed that every time whenever GRAP task force took action, the pollution level decreased significantly and the situation was under control. It was observed that whenever GRAP was implemented, the the AQI values of both PM 2.5 and NO 2 decreased drastically. This was possible due to stringent steps such as restriction on entry of heavy vehicles, ban on construction activities, introduction of odd-even scheme for vehicles, closure of schools during severe condition, closure of brick kilns and stone crushers; ban on diesel generator sets and burning in landfills and parks etc. taken by the authorities. Therefore, the suggestive outcome of study is to formulate similar task forces in every mega city of India for providing neat and clean air to 179 and 97 for PM 2.5 and 32 and 46 for NO 2 during the months of September, 2017 and 2018 respectively.
our citizens. Also, there is need to prepare a fresh inventory of air pollution sources in residential areas.