Tropospheric NO₂ Trends over South Asia during the Last Decade (2004–2014) Using OMI Data

Table 1

Statistics of tropospheric NO₂ (×10¹⁵ molec/cm²) over South Asian countries, hotspots, and some major cities using OMI/Aura data during 2005–2014.

Name of the country/hotspot area/city	Location	Population (million)	Area (km^2)	Average; (×10^15 molec/cm^2)	Decadal trend; (%)	Trend parameters; = slope ± error; = y intercept ± error (×10^15 molec/cm^2)	Highest monthly value; (×10^15 molec/cm^2)	Lowest monthly value; (×10^15 molec/cm^2)
Bangladesh	23.70°N, 90.35°E	156.6	147,570	1.75 ± 0.13	23	= 0.04039 ± 0.01063,; = 1.54966 ± 0.05983,; = 0.67337	2.95; (Mar.-11)	0.95; (Jul.-05)
India	21.00°N, 78.00°E	1252	3,287,590	1.66 ± 0.08	17	= 0.02912 ± 0.00452,; = 1.51498 ± 0.02541,; = 0.85592	1.16; (Jul.-06)	2.36; (Mar.-11)
Afghanistan	34.53°N, 69.13°E	31	652,864	0.81 ± 0.04	16	= 0.01362 ± 0.00358,; = 0.74361 ± 0.02012,; = 0.67459	1.25; (Jul.-10)	0.49; (Oct.-05)
Nepal	26.53°N, 86.73°E	27	147,181	1.05 ± 0.05	13	= 0.01452 ± 0.00464,; = 0.98200 ± 0.02614,; = 0.58262	1.70; (Apr.-09)	0.71; (Jan.-06)
Pakistan	33.66°N, 73.16°E	182	796,095	1.24 ± 0.05	13	= 0.01706 ± 0.00383,; = 1.15578 ± 0.02154,; = 0.73952	1.53; (Jul.-10)	0.94; (Nov.-05)
Maldives	3.20°N, 73.22°E	0.3	300	0.20 ± 0.01	10	= 0.00239 ± 0.00098,; = 0.19713 ± 0.00549,; = 0.46181	0.33; (Feb.-06)	0.09; (Sep.-05)
Sri Lanka	7.00°N, 81.00°E	20.4	65,610	0.71 ± 0.01	6	= 0.00471 ± 0.00203,; = 0.68708 ± 0.01141,; = 0.43601	0.88; (May-06)	0.582; (Oct.-07)
Bhutan	27.41°N, 90.43°E	0.7	38,394	0.83 ± 0.04	5	= 0.00464 ± 0.00628,; = 0.80861 ± 0.03533,; = 0.07251	1.63; (Mar.-09)	0.48; (Aug.-05)
Dhaka; (Dhaka Division, Bangladesh)	23.48°N, 90.24°E	14.39	815	3.15 ± 0.51	77	= 0.190 ± 0.02121,; = 2.2012 ± 0.119355,; = 0.9198	6.25; (Jan.-11)	1.31; (Jul.-06)
Islamabad; (Capital of Pakistan)	33.40°N, 73.00°E	2.1	1060	2.32 ± 0.43	69	= 0.12912 ± 0.03554,; = 1.67488 ± 0.19997,; = 0.65351	4.68; (Dec.-10)	1.19; (Sep.-06)
Kabul; (Capital of Afghanistan)	34.33°N, 69.08°E	3.5	425	1.74 ± 0.27	68	= 0.09677 ± 0.01071,; = 1.26159 ± 0.06026,; = 0.92105	5.03; (Jan.-13)	1.01; (Mar.-05)
Korba; (Chhattisgarh, India)	22.35°N, 82.68°E	1.01	6,598	3.23 ± 0.44	64	= 0.1699 ± 0.012827,; = 2.3838 ± 0.072183,; = 0.9616	5.82; (Jun.-08)	1.44; (Feb.-05)
Bardhaman; (West Bengal, India)	23.33°N, 87.30°E	0.34	56	3.23 ± 0.38	47	= 0.1363 ± 0.011839,; = 2.5578 ± 0.066623,; = 0.9498	5.89; (Dec.-13)	1.47; (Aug.-06)
Lahore; (Punjab, Pakistan)	31.32°N, 74.22°E	10.23	1,172	3.22 ± 0.31	40	= 0.1176 ± 0.013978,; = 2.6338 ± 0.078661,; = 0.91	5.95; (Oct.-13)	1.82; (Sep.-06)
Pakur; (Jharkhand, India)	23.30°N, 86.40°E	0.89	686	3.07 ± 0.26	35	= 0.102 ± 0.008346,; = 2.5619 ± 0.046963,; = 0.9552	5.19; (Sep.-12)	1.58; (May-05)
Chittagong; (Chittagong Div, Bangladesh)	22.36°N, 91.80°E	4.6	157	1.61 ± 0.15	31	= 0.04878 ± 0.01076,; = 1.37594 ± 0.06054,; = 0.74601	4.03; (Mar.-11)	0.58; (Jul.-09)
Faisalabad; (Punjab, Pakistan)	31.41°N, 73.07°E	6.5	5,856	2.48 ± 0.21	29	= 0.06997 ± 0.01379,; = 2.13633 ± 0.07759,; = 0.78626	3.79; (Jan.-11)	1.54; (Sep.-11)
Rajshahi; (Rajshahi Division, Bangladesh)	24.36°N, 88.60°E	0.8	2,407	2.43 ± 0.19	26	= 0.06211 ± 0.01320,; = 2.12518 ± 0.07426,; = 0.75987	4.27; (Dec.-12)	1.16; (Jul.-10)
Bengaluru; (Karnataka, India)	12.96°N, 77.56°E	4.30	741	1.88 ± 0.11	21	= 0.04048 ± 0.00602,; = 1.67940 ± 0.03390,; = 0.86579	3.33; (Mar.-11)	0.99; (Jul.-06)
Delhi; (National Capital Region of India)	28.67°N, 77.22°E	16.31	1,484	3.20 ± 0.19	21	= 0.0697 ± 0.008978,; = 2.8575 ± 0.050523,; = 0.896	5.31; (Jan.-08)	1.99; (Aug.-06)
Singrauli; (Madhya Pradesh, India)	24.12°N, 82.39°E	1.17	2,200	3.71 ± 0.27	21	= 0.0783 ± 0.02638,; = 3.3193 ± 0.148447,; = 0.5574	5.55; (Aug.-13)	1.55; (Aug.-11)
Angul; (Odisha, India)	20.83°N, 85.01°E	1.27	6,232	2.73 ± 0.16	19	= 0.0527 ± 0.013024,; = 2.4762 ± 0.073292,; = 0.7001	4.59; (Mar.-11)	1.12; (Jul.-06)
Hyderabad; (Telangana, India)	17.37°N, 78.48°E	9.5	650	2.06 ± 0.15	19	= 0.04071 ± 0.01533,; = 1.86456 ± 0.08629,; = 0.50165	3.6; (Mar.-11)	1.06; (Aug.-13)
Chennai; (Tamil Nadu, India)	13.08°N, 80.27°E	4.34	426	2.33 ± 0.21	19	= 0.04669 ± 0.02416,; = 2.10360 ± 0.13594,; = 0.34802	3.31; (Mar.-11)	1.93; (Jul.-13)
Lucknow; (Uttar Pradesh, India)	26.80°N, 80.90°E	3.7	2,528	2.14 ± 0.10	15	= 0.03362 ± 0.00609,; = 1.97686 ± 0.03427,; = 0.81324	2.99; (Jan.-12)	1.35; (Jul.-08)
Kolkata; (West Bengal, India)	22.55°N, 88.31°E	14.11	1,886	2.63 ± 0.13	15	= 0.0411 ± 0.011804,; = 2.4314 ± 0.066426,; = 0.6343	4.27; (Oct.-10)	1.43; (Jul.-12)
Kathmandu; (Capital of Nepal)	27.27°N, 85.33°E	0.7	50.67	1.03 ± 0.05	13	= 0.01412 ± 0.00630,; = 0.96398 ± 0.03546,; = 0.41776	1.85; (Apr.-09)	0.485; (Jan.-06)
Sylhet; (Sylhet Division, Bangladesh)	24.90°N, 91.86°E	2.6	26.5	1.35 ± 0.01	12	= 0.01765 ± 0.01109,; = 1.26824 ± 0.06240,; = 0.26568	2.98; (Mar.-09)	0.61; (Jul.-05)
Gadanki; (Andhra Pradesh, India)	13.48°N, 79.20°E	Few thousands	Few acres	1.16 ± 0.06	9	= 0.01194 ± 0.00784,; = 1.10182 ± 0.04410,; = 0.24890	2.16; (Mar.-11)	0.44; (Jul.-13)
Mumbai; (Maharashtra, India)	19.04°N, 72.52°E	12.47	4,355	2.14 ± 0.08	7	= 0.0163 ± 0.011462,; = 2.0635 ± 0.064502,; = 0.2243	4.08; (Sep.-12)	0.48; (Aug.-09)
Karachi; (Sindh, Pakistan)	24.51°N, 67.72°E	16.05	3,527	2.00 ± 0.10	6	= 0.0144 ± 0.014674,; = 1.9283 ± 0.082573,; = 0.1211	3.36; (Feb.-08)	1.08; (Sep.-11)
Ahmedabad; (Gujarat, India)	23.03°N, 72.78°E	3.52	464	3.03 ± 0.10	4	= 0.01725 ± 0.01369,; = 3.12073 ± 0.07701,; = 0.18491	4.28; (Dec.-10)	1.727; (Jul.-05)
Colombo; (Capital of Sri Lanka)	6.93°N, 79.84°E	6.4	37.31	1.32 ± 0.15	3	= 0.00503 ± 0.02161,; = 1.30349 ± 0.12158,; = 0.00769	3.3; (Jan.-12)	0.39; (Jul.-13)
Kanpur; (Uttar Pradesh, India)	26.28°N, 80.24°E	2.5	1,680	2.17 ± 0.04	2	= 0.00442 ± 0.00584,; = 2.15486 ± 0.03285,; = 0.07553	2.99; (Dec.-13)	1.18; (Mar.-12)
DG Khan; (Punjab, Pakistan)	30.03°N, 70.38°E	2.12	11,294	1.80 ± 0.12	−11	= −0.02401 ± 0.01464,; = 1.92591 ± 0.08238,; = 0.27753	2.53; (Jan.-08)	1.12; (Oct.-11)