Measurement of NO 2 Concentration in Ambient Air in Karachi using Diffusion Sampling By Zia-ul-Islam Director, Pak-EPA

Why NO 2 ? Important Air Pollutant and very Critical Role in the Atmospheric Chemistry In Atmosphere, NO 2 Converted to Nitric Acid and Nitrate. NO 2 is Phytotoxic in nature and adverse effects on crop yield. NO 2 is an important precursor of Ozone formation.

Measurement Methods ► Passive Sampling (Diffusion Sampling) ► Active Sampling (Semi-Automatic) ► Automatic Sampling ► Remote Sensors Diffusion (Passive) sampling was used to monitor the NO 2 Concentration in Karachi and other major cities of Pakistan.

Why Diffusion Sampling? Pollutants in the atmosphere are influenced by the weather and chemistry, thus making it difficult to know, where they will concentrate and cause poor air quality. The only way to be certain of this is to monitor the air pollution at as many sites as possible in one time. This can only be done by Diffusion (Passive) sampling.

Structure of Diffusion Sampler

Diffusion Method Used in the Present Study The method used in this study has been developed by Japanese Scientist Kazuyuki Aoki in This method has application for outdoor measurements due to improvement of diffusion path. This method can be used for measuring a wide range of gas species like NO 2, NO, NH 3 and SO 2.

Procedure for Using Diffusion Sampler for NO 2 Monitoring Preparation of Diffusion Sampler -Chemicals 1.Triethanolamine 2.Dimethyl Sulfoxide 3.Phosphoric Acid 4.Sulphanilamide 5.NEDA.2HCl 6.Sodium Nitrite

Sampler Preparation

Exposure of Diffusion Samplers

Meteorological Monitoring Meteorological Equipment used during this study 1.Thermo-hygrometer (for ambient temperature & Relative Humidity) 2.Anemometer (Wind Speed Meter and Direction Detector)

Relative Humidity & Average Ambient Temperature in Karachi During Study Period Maximum and Minimum temperature varied between 30.9 o C and 23.2 o C Maximum and Minimum Relative Humidity varied between 30.3% and 20.8%

Wind Direction and Wind Speed During Monitoring in Karachi Easterly wind was blowing throughout the monitoring period Maximum and Minimum wind speed were 2.54 m/s and 1.2 m/s respectively

Sampling Locations in Karachi 35 sampling sites were selected in Karachi These sites were categorized as: 1.Industrial 2.Residential 3.Commercial 4.Kerbsides

Sampling Locations in Karachi

NO 2 Concentration in Ambient Air at Various Locations in Karachi Location Absorbanc e Sample Absorbance Blank Exposure Time (Hours) NO 2 Concentration ppbµg/m 3 Korangi Industrial Area Landhi # Rangers Office Malir

Location Absorbanc e Sample Absorbance Blank Exposure Time (Hours) NO 2 Concentration ppbµg/m 3 Airport Gulustan-e- Johar SUPARCO Center Teanhati Ranshorline Lea Market Lyari

Location Absorbanc e Sample Absorbance Blank Exposure Time (Hours) NO 2 Concentration ppbµg/m 3 Balidia Town Sea Front Clifton DHA KPT Building West Warf CDGK

Location Absorbanc e Sample Absorbance Blank Exposure Time (Hours) NO 2 Concentration ppbµg/m 3 Saddar Mazar-e-Quaid Bahadurabad Mahmoodabad FTC Building Kiyamari North Karachi North Nazimzbad

Location Absorbanc e Sample Absorbance Blank Exposure Time (Hours) NO 2 Concentration ppbµg/m 3 Karimabad Mac Donald N. Nazimabad SITE Tamuria Library Gulshan-e- Iqbal NIPA Super High w Hasan Square Aladin Park

Distribution Pattern of NO 2 in Karachi

Highlights of the Results The Highest Concentration was found at Karimabad Junction ( µg/m 3 ) The second highest concentration was found at Aaladin Park on Shahrah-e- Rashid Minhas ( µg/m 3 ) The Third most polluted site was Civic Center near Hasan Square ( µg/m 3 ) NO 2 Concentration at Korangi Industrial Area was µg/m 3.

Comparison with International Standards If compared with Japanese standard (80 µg/m 3 for 24 hours average), NO 2 concentration at 8 locations are higher in Karachi. WHO Guidelines (150 µg/m 3 ), Only one location Karimabad showed two fold higher conc.

Conclusion Emission of NO 2 is used as an indicator to evaluate the environmental performance of national policies. In the recent years, the ambient NO 2 concentration has exhibited an increase. Even though by the introduction of cleaner fuel (CNG). Due to Non-existence of fixed ambient air monitoring stations, the increasing or otherwise trend could not be established. Presently Pak-EPA with the grant aid of Japan is establishing two fixed and one mobile monitoring stations in Karachi. After establishment of these stations, Pak-EPA will be in a position to formulate the policies of air emission abatement.

Conclusion With respect to traffic density viz e viz Kerbside installed samplers, the present study revealed: 1.NO 2 concentration decreases according to distance from road 2.The samplers, which are installed more than 30 meters from road, their NO 2 concentration are more or less similar (Stable) 3.It means background concentration in Karachi is ≈ 30 ppb ( which is still in the safe limits).