Ambient Air Quality in Delhi

As a result of various measures taken for vehicular emission control in Delhi, considerable changes have been observed in the ambient air quality during the year 2003 in comparison to year 2002.

» The levels of SO2 were found to be within the permissible limits at all the monitoring locations . As compared to year 2002 there has been 18 % reduction in SO2 levels on an average.
» The levels of both SPM and RSPM were not meeting national ambient air quality standards at any monitoring locations. As compared to the year 2002, there has been reduction in levels of both SPM and RSPM by 14% & 11 % respectively during the year 2003.
» CO levels were found to be within standards with a reduction of 13 % during the year 2003 as compared to 2002.
» The levels of NO2 have increased slightly at all the monitoring locations i.e. residential, industrial, traffic intersections. Overall there has been increase of 15% in the levels of NO2 during 2003 as compared to 2002.

Measurement of Benzene Soluble Organic Fraction in PM10

Benzene Soluble Organic Fraction (BSOF) mainly comprise hundreds of particulate bound organic compounds present in ambient air. Some of the important BSOF compounds include Polycyclic Aromatic Hydrocarbons (PAHs), Dioxins and Furans, Oxidized Hydrocarbons (aldehydes, ketones, oxyacids etc.). Measurement of BSOF gives an idea about the anthropogenic emissions originating from the combustion of fossil fuels. BSOF is being sporadically measured in RSPM or PM10 at BSZ Marg Traffic Intersection Delhi since 2001. Preliminary results indicate that BSOF during the winter months were higher ranging from 34 - 70 µg/m3, while the lowest values (16 µg/m3) were observed in monsoon period. Alarmingly high levels of RSPM ranging between 800 - 900 µg/m3 was observed during summer months (May and June 2003), however the BSOF levels in such high concentrations of RSPM was found to be only 3 - 4% of RSPM. This clearly reveals that the high levels of RSPM observed in Delhi is mainly contributed by natural sources such as wind blown dust and re-suspension of soil dust. This was further demonstrated during monsoon period (July 2003) when average RSPM was found only 67 µg/m3 (perhaps due to wet deposition factor) but the BSOF even at such low levels of RSPM was found highest (25%) in comparison to other months.

Benzene Levels in Ambient Air of Delhi During 2003 (Passive Method)

Benzene is one of the volatile organic compound (VOC). The VOCs is a collective name for a large but heterogeneous group of organic compounds having a vapor pressure greater than 10-1 mm Hg at 25 0 C and 760 mm Hg. Benzene is a harmful pollutant causing exposure-related health affects in human beings. It is mainly released from anthropogenic activities such as transportation (from vehicles exhaust, filling and evaporative losses), industrial processes, combustion etc.

Central Pollution Control Board is continuously monitoring benzene in Delhi using diffusive samplers (passive sampling method) at seven locations namely Ashok Vihar, I.T.O, J.N.U., Moti Nagar, East Arjun Nagar, SiriFort and Town Hall. Minimum, maximum and mean concentration of benzene at different locations of Delhi during year 2003 is presented below. The mean concentration of benzene ranged between 6 µg/m3 (J.N.U) to 14 µg/m3 (I.T.O). The maximum concentration of 26 µg/ m3 and the minimum concentration of 2 µg/m3 were observed at I.T.O. and J.N. U. respectively.

Levels of Benzene during Peak and Lean Hours of Traffic in Delhi

Benzene monitoring was conducted during peak traffic hours (between 8am - 10 am and 6 pm - 8 pm) and the lean traffic hours (12 noon - 2 pm and 3 pm - 5 pm) at different locations in Delhi during January 2003.The selected locations were Preet Vihar (petrol pump) CBD CNG fill station near Karkardooma Court complex ,ITO (traffic intersection) and Siri Fort. Samples were collected using charcoal tube and Low volume sampler (active sampling method). The collected samples were analysed using CS2 desorption and GC-FID techniques. The concentrations of the Benzene during peak & lean hours of traffic are presented below.

Ambient Air Quality Monitoring at Agra

The Air Quality Monitoring station at Agra was initiated in compliance to the direction of the Hon'ble Supreme Court of India. The monitoring stations were established to monitor SPM, RSPM, NO2 and SO2 in the ambient air at Agra at four locations all around the year. The locations are: Varadarajan, Rambagh, Nunhai (industrial areas), Itmad-ud-daulah (historical monument surrounded by industrial areas) and Taj Mahal (the world famous monument). The air quality data generated and its variation over time and space is depicted at various locations are presented in following figures.

RSPM Levels (Monthly Mean) in Ambient Air at Agra in year 2002 & 2003

SPM Levels (Monthly Mean) in Ambient Air at Agra in year 2002 & 2003

NO2 Levels (Monthly Mean) in Ambient Air at Agra in year 2002 & 2003

SO2 Levels (Monthly Mean) in Ambient Air at Agra in year 2002 & 2003

The data revealed that with respect to all the air quality parameters (except in case of SO2), Taj Mahal monitoring location has lowest concentrations and Nunhai has the highest.

Ambient Air Quality monitoring at Vikasnagar,Kanpur:

Regular monitoring of SO2, NOx and RSPM is being conducted at Vikasnagar, Kanpur, round the clock on all working days .The data is being disseminated on web site of CPCB. Monthly average of RSPM and NOx for the year 2003 have been presented below:

The findings are as follows:

· RSPM concentration was observed high as compared to ambient air quality standards throughout the year except during monsoon months. Exceptionally higher values in summer was due to localized construction activities.
· NOx concentration ranges 13 µg/m3 to 38 µg/m3 which is much lower than the prescribed air quality standards.
· SO2 was observed very low all over the year.

Continuous BTX Monitoring at Kanpur

CPCB is continiously monitoring Benzene, Toluene, Ethyl benzene, m+p Xylene and O-Xylene, at typical residential-cum-institutional area of Kanpur. The data during typical winter month of December-2003 has been presented ahead. The values presented are average daily values for all five parameters of BTX analyser.

The maximum concentration of Toluene has been observed on 15.12.2003 amounting to 299 µg/m3. This value is approximately 8 times the normal average concentrations observed in this part of Kanpur city. The values of Ethyl benzene can be observed as the follower of the toluene values.

The reasons as identified in this area for such high concentrations in this part of Kanpur are:

» Burning of tyres
» Burning of wood chullahs
» Burning of wood in open area during evening hours of winter season for heating
» Continuous movement of vehicles at Grand Trunk road etc.

Standardization of methodology for PAH compounds and measurement of PAH in Kolkata.

Poly-cyclic aromatic hydrocarbons (PAH) are important organic aerosol components generated in a variety of combustion processes and emitted into the atmosphere preferentially associated with the sub-micron size particles. Some species of PAH are known human carcinogens. Therefore, it is felt to standardise the methodology for measurement of 6 PAH species initially and to generate data regarding levels of PAH in ambient air of historical places namely Dakshineswar, Belur and Victoria Memorial.

Ambient Air Quality of Puri town

The air quality of Puri is influenced by the increase in various activities like transportation, hotel Industry, burning of solid waste etc. In order to assess the quality of ambient air in Puri town, a study was conducted by Orissa State Pollution Control Board with financial assistance from CPCB.

Average concentration of NOx was observed within safe limit (80 µg/m3) during all seasons, however at Bilapanda there were some instances when NOx levels exceeded beyond the safe limits. The average 24-hr NO2 levels at Puri were found between 2.5 to 46.4 µg/m3 during the year while the average values of all seasons was found between 13.4 to 33.7 µg/m3. Respirable dust levels have increased the 24-hour limit of 100 µg/m3 at Mausima Temple and Baliapada stations during winter and summer.

From the study it can be concluded that air pollution in Puri town is not alarming, however to sustain the air quality and to further improve the air quality, immediate steps are required to be taken by improving road network, management of vehicular traffic restrictions, burning of wood, hard coal, garbage etc. within the town limits.

Studies on Sulphates and Nitrates in the Ambient Air

The project studies was initiated to study the fate of acidic gases in the atmosphere. The acidic gases like SOx and NOx are reactive and form sulphate, nitrates and other secondary pollutants in the atmosphere during short time, which is not reflected in routine measurements of air quality. In the first phase of the project, samples at various atmospheres like problem areas, secured landfill sites, industrial areas and residential areas have been collected for analysis of Sulphates and Nitrates in different seasons. Results indicated that at Subhanpura, Vadodara (residential area), the monthly average values of sulphate in ambient air varied between 0.84 µg/m3 and 9.9 µg/m3.