Table 2 : CATEGORISATION OF INTERSECTIONS BASED ON TRAFFIC DENSITY

S.N.	Traffic Volume*	Nos.	Class	Traffic Intersections
1.	More than 30,000		I	08. Delhi Gate
				05. Moolcvand
2.	25,000 to 29,000		II	04.A.I.I.M.S.
				07. India Gate
3.	20,000 to 24,999		III	10. Red fort
				12. Moti Nager
				09. Yamuna Bazar
				06. Ashram
				03. R.k. Puram
4.	15,000 to 19,999		IV	02. Dhaula Kuan
				01. Raja Garden
				11. Zakhira
5.	Less than 15,000		V	13. Azadpur

*Petrol-driven Vehicles during 6 hr (Table 1)

2. Ambient Air Quality : The ambient air sampling and analysis for Pb, Suspended Particulate Matter (SPM), SO2 and NO2 was done as per Standard Methods8.

3. Lead in Soil : The soil samples were collected in triplicate from top, bottom and middle portion of the pots of each species from every location. A composite sample was thus made for each species at every location. Precautions were taken to maintain uniformity in all soil sampling. Surface vegetation and debris, if any, were removed before sampling. Soil samples were dried for a minimum of 30 hr. After screening, the soil was pulverized and sieved through an 80-mesh screen. Lead content in the soil samples was determined by conventional atomic absorption Spectrophotometry9.

4. Lead in Plants : Three plant species from six different locations were analysed in triplicate after scrubbing (leaf and shoot) and washing with water (root) for the lead content of the root, shoot and leaf using mixture of sulphuric and nitric acid for digestion9. The test samples were processed on Atomic Absorption Spectrophotometer for estimation of lead. The dust deposited on leaves of different plant species was collected separately in pre-weighed beakers using a jet of double glass distilled water. The beaker was dried in 80°C oven for 24 hr, weighed and lead content of the dust in the beaker was determined.

Table 3 : TRAFFIC FLOW AND AMBIENT AIR QUALITY AT SELECTED TRAFFIC INTERSECTIONS AND NPL NURSERY

S.N.	Name Of Location	Traffic Volume Nos.	Ambient Air Quality (10-hr average)
			SO2	NO2	SPM	Pb
				ug/m3		ng/m3
1.	Delhi Gate	36,923	36	49	696	193
2.	India Gate	28,414	15	20	81	90
3.	Red Fort	23,871	45	80	460	166
4.	Ashram	18,009	30	25	382	192
5.	Azadpur	15,608	40	75	818	277
6.	NPL Nursery	NIL	11	15	83	46

* Petrol-driven Vehicles during 6 hr (Table 1)

5.Plant Growth : The general growth of the plant species at six different locations was studied using the parameters : total chlorophyll10, total biomass11, leaf area (using LICOR 3000 Area Meter).

RESULTS AND DISCUSSION

Lead in the Roadside Ambient Air: The concentration of lead in ambient air at 13 traffic intersections was in the range 280 ng/m3 and 1,802 ng/m3 and SO2 and NO2 were mostly less than 100 ug/m3 in Jan. 1984. At the same intersections in June 1984, lead ranged between 170 ng/m3 and 926 ng/m3 while SO2 and NO2 did not exceed 100 ug/m3.

The lead in ambient air at five finally chosen traffic intersections and also at the control site within NPL Nursery was monitored once-a-month for 10 months from July 1984 to June 1985. No measurements could be conducted during November and December, 1984. Air quality monitoring was done for different periods of the time of the. day, as follows

AUTOEXHAUST LEAD

09.00 to 12.00 hr morning peak traffic hours 16.00 to 19.00 hr evening peak traffic hours 12.00 to 16.00 hr mid-day lean traffic hours 09.00 to 19.00 hr 10-hour day time traffic hours

Table 4 : AMBENT AIR LEAD CONTENT AT SIX DIFFERENT LOCATIONS*

S.N.	Location	Traffic Volume Class	Concentration of lead, ng/m3
			9 am to 12 noon (3-hrly)	12 noon to 4 pm (4-hrly)	4 pm to 7 pm (3-hrly)	9 am to 7 pm (10-hrly)
			A	B	C	D
1.	Delhi Gate	I	312	297	336	297
2.	India Gate	II	306	237	240	185
3.	Red Fort	III	353	270	436	287
4.	Ashram	IV	376	373	391	324
5.	Azadpur	V	336	328	298	252
6.	NPL Nursery	-	47	42	38	62

* Between July 1984 and June 1985