Canada’s Air Pollutant Emissions Inventory Report 2022: chapter 2.3

2.3 Nitrogen oxides (NO_x)

Approximately 1.4 Mt of nitrogen oxides (NOx) were released in Canada in 2020 (Table 2–5). Transportation and Mobile Equipment was the largest contributor, accounting for 47% (682 kt) of total NO_x emissions. Within this source category, Heavy-Duty Diesel Vehicles, Off-Road Diesel Vehicles and Equipment and Rail Transportation were the largest emitters, collectively contributing 32% (461 kt) of total NO_x emissions. The Oil and Gas Industry accounted for 31% (449 kt) of total NO_x emissions in 2020, with the Upstream Oil and Gas Industry sector accounting for nearly all of the Oil and Gas Industry total (96% or 433 kt). Electric Power Generation (Utilities) contributed 7.0% (101 kt) of total NO_x emissions, with coal-fired generation contributing 4.6% (66 kt) of the national total. The remaining 17% of NO_x emissions were distributed across multiple sources.

From 1990 to 2020, national NOx emissions decreased by 36% (826 kt) (Figure 2–3). A significant driver of this trend was the decrease in emissions from Light-Duty Gasoline Trucks and Vehicles, as a result of increasingly stringent vehicle regulations that have effectively lowered NO_x and hydrocarbon emissions from engines.^{Footnote 4} Emissions from Off-Road Diesel Vehicles and Equipment and Heavy-Duty Diesel Vehicles increased at the beginning of the time series and decreased after 2000 and 2005, respectively. Between 2019 and 2020, Transportation and Mobile Equipment showed a emission decrease of NO_x (92 kt or 12%). This reduction is mostly due to a decrease in the VKT in the Light-Duty Gasoline Vehicles and Trucks categories.

Within Electric Power Generation (Utilities), Coal contributed to the downward trend across the time series, with a gradual decrease in emissions from 1998 to 2020. This decrease can be attributed to coal-fired power plants that have closed down and have been replaced by lower-emission sources such as natural gas power plants.

Between 2019 and 2020, most major contributors to NO_x emissions experienced decreases. Notably, the Upstream Oil and Gas Industry saw a significant decrease of 34 kt (7.2%) which can be partly attributed to a 5% reduction in total crude oil production and a 2% reduction in natural gas production. Finally, the Upstream Oil and Gas Industry sector experienced an increase in emissions since 1990. This increase is attributed to expansion and growth in the oil and gas industry.

The most significant changes in NOx emissions from 1990 to 2020 include:

Transportation and mobile equipment: decrease of 47% (607 kt), with:
- Off-road diesel vehicles and equipment: decrease of 57% (190 kt)
- Light-duty gasoline trucks and vehicles: decrease of 69% (202 kt)
- Rail Transportation: decrease of 47% (77 kt)
Electric power generation (utilities): decrease of 61% (156 kt), with:
- Coal: decrease of 68% (140 kt)
Oil and gas industry: increase of 30% (103 kt), of which:
- Upstream oil and gas industry: increase of 39% (122 kt)
- Downstream oil and gas industry: decrease of 54% (19 kt)

Figure 2–3: Trends in Canadian NO_x emissions (1990 to 2020)

Long description for Figure 2–3

Figure 2–3 is a stacked area graph displaying the six major contributors to national NO_x trends. They are the following: Coal (Electric power generation), Rail Transportation, Off-Road Diesel vehicles and Equipment, Heavy-Duty Diesel Vehicles, Upstream Oil and Gas Industry, and Other. The figure shows that the shares of Other and Upstream Oil and Gas Industry were almost equivalent in 2020. The following table displays the contributions (kt) for the years 1990 to 2020.

Figure 2–3: Trends in Canadian NO_x emissions (1990 to 2020) (kt)
Sector	1990	1991	1992	1993	1994	1995	1996	1997	1998	1999	2000	2001	2002	2003	2004	2005	2006	2007	2008	2009	2010	2011	2012	2013	2014	2015	2016	2017	2018	2019	2020
Upstream Oil and Gas Industry	311	306	325	349	380	399	413	456	471	487	430	422	421	464	396	400	404	428	439	436	432	446	443	447	460	461	454	464	470	466	433
Heavy-Duty Diesel Vehicles	293	254	239	238	251	254	280	327	368	406	414	403	386	384	378	408	384	369	355	325	325	325	303	289	264	239	232	244	256	255	230
Off-Road Diesel Vehicles and Equipment	334	323	324	355	395	426	419	419	375	355	356	307	297	313	311	282	258	258	250	235	251	225	194	187	171	166	132	144	154	152	144
Rail Transportation	165	153	160	159	165	149	146	148	143	151	153	149	137	123	122	126	130	133	136	114	110	122	121	112	109	98	88	93	93	94	88
Coal	206	205	211	192	188	198	208	222	235	227	225	220	215	209	194	186	173	181	169	151	153	132	126	124	129	115	117	110	92	88	66
Other	965	948	969	987	1 015	1 027	1 054	1 086	1 105	1 133	1 151	1 095	1 084	1 008	962	863	764	752	700	665	669	636	589	569	548	535	533	550	556	555	487

Table 2–5: National summary of annual NO_x emissions

Notes:
Totals may not add up due to rounding.
0.00 Indicates emissions were truncated due to rounding.
- Indicates no emissions

Ore and Mineral Industries (tonnes)
Sector	1990	2000	2005	2015	2016	2017	2018	2019	2020
Sub-total	100 000	99 000	110 000	81 000	77 000	86 000	82 000	80 000	74 000
Aluminium Industry	1 600	1 400	2 000	1 100	1 200	1 200	1 200	1 100	1 100
Asphalt Paving Industry	1 200	1 100	1 200	930	890	960	980	930	880
Cement and Concrete Industry	42 000	45 000	54 000	35 000	32 000	34 000	35 000	31 000	27 000
Foundries	510	660	510	43	42	43	43	42	42
Iron and Steel Industry	19 000	16 000	13 000	11 000	11 000	11 000	11 000	10 000	8 400
Iron Ore Pelletizing	5 200	5 100	9 500	11 000	10 000	10 000	8 500	9 800	9 300
Mineral Products Industry	1 400	670	1 100	290	300	290	240	210	220
Mining and Rock Quarrying	29 000	26 000	24 000	21 000	20 000	27 000	23 000	25 000	25 000
Non-Ferrous Mining and Smelting Industry	4 200	3 700	1 800	1 600	1 900	1 800	1 700	1 900	1 500

Oil and Gas Industry (tonnes)
Sector	1990	2000	2005	2015	2016	2017	2018	2019	2020
Sub-total	350 000	460 000	430 000	480 000	470 000	480 000	490 000	480 000	450 000
Downstream Oil and Gas Industry	35 000	30 000	31 000	17 000	17 000	17 000	16 000	15 000	16 000
Upstream Oil and Gas Industry	310 000	430 000	400 000	460 000	450 000	460 000	470 000	470 000	430 000

Electric Power Generation (Utilities) (tonnes)
Sector	1990	2000	2005	2015	2016	2017	2018	2019	2020
Sub-total	260 000	330 000	250 000	150 000	150 000	140 000	130 000	120 000	100 000
Coal	210 000	230 000	190 000	110 000	120 000	110 000	92 000	88 000	66 000
Diesel	3 100	8 300	8 500	9 900	9 100	8 900	9 700	9 800	9 100
Natural Gas	20 000	65 000	38 000	17 000	16 000	16 000	18 000	18 000	18 000
Waste Materials	45	200	68	36	72	96	45	27	14
Other (Electric Power Generation)	28 000	28 000	21 000	11 000	10 000	9 700	9 200	9 100	8 100

Manufacturing (tonnes)
Sector	1990	2000	2005	2015	2016	2017	2018	2019	2020
Sub-total	190 000	170 000	140 000	69 000	68 000	69 000	69 000	67 000	63 000
Abrasives Manufacturing	240	90	74	-	-	-	-	-	-
Bakeries	4.1	4.0	-	0.89	0.89	0.95	-	-	-
Biofuel Production	-	-	-	18	16	18	33	13	33
Chemicals Industry	41 000	47 000	37 000	23 000	23 000	23 000	25 000	24 000	24 000
Electronics	150	160	71	-	0.00	-	-	-	-
Food Preparation	2 400	2 800	3 300	1 800	1 700	1 900	1 900	1 700	1 600
Glass Manufacturing	7 000	7 400	6 100	920	780	780	770	750	750
Grain Industry	1 400	1 300	990	780	760	1 100	820	930	430
Metal Fabrication	5 800	8 900	1 200	440	470	400	450	370	370
Plastics Manufacturing	820	770	98	9.4	11	13	18	14	12
Pulp and Paper Industry	72 000	49 000	45 000	30 000	29 000	29 000	28 000	27 000	25 000
Textiles	120	170	110	8.2	7.8	7.8	7.7	6.1	0.20
Vehicle Manufacturing (Engines, Parts, Assembly, Painting)	2 300	3 200	1 500	650	610	600	660	620	470
Wood Products	18 000	22 000	19 000	11 000	12 000	11 000	11 000	11 000	10 000
Other (Manufacturing)	34 000	31 000	22 000	480	510	420	540	530	380

Transportation and Mobile Equipment (tonnes)
Sector	1990	2000	2005	2015	2016	2017	2018	2019	2020
Sub-total	1 300 000	1 600 000	1 200 000	750 000	710 000	740 000	770 000	770 000	680 000
Air Transportation (LTO)	5 700	6 800	6 800	7 100	7 300	7 600	8 500	8 500	4 600
Domestic Marine Navigation, Fishing and Military	59 000	70 000	77 000	60 000	60 000	62 000	65 000	69 000	63 000
Heavy-Duty Diesel Vehicles	290 000	410 000	410 000	240 000	230 000	240 000	260 000	260 000	230 000
Heavy-Duty Gasoline Vehicles	60 000	82 000	60 000	35 000	37 000	37 000	38 000	38 000	29 000
Heavy-Duty LPG/NG Vehicles	15 000	34 000	4 500	61	80	140	140	130	160
Light-Duty Diesel Trucks	790	1 500	2 100	1 400	1 600	1 800	2 000	2 000	1 800
Light-Duty Diesel Vehicles	2 200	2 200	1 200	920	860	860	830	800	580
Light-Duty Gasoline Trucks	97 000	190 000	130 000	68 000	72 000	74 000	77 000	79 000	61 000
Light-Duty Gasoline Vehicles	200 000	220 000	120 000	46 000	46 000	45 000	44 000	43 000	30 000
Light-Duty LPG/NG Trucks	7 500	5 900	2 900	27	29	34	34	33	20
Light-Duty LPG/NG Vehicles	820	740	280	0.73	0.89	1.2	1.2	1.1	0.85
Motorcycles	320	440	530	640	680	700	700	700	580
Off-Road Diesel Vehicles and Equipment	330 000	360 000	280 000	170 000	130 000	140 000	150 000	150 000	140 000
Off-Road Gasoline/LPG/NG Vehicles and Equipment	53 000	37 000	28 000	30 000	29 000	30 000	31 000	31 000	30 000
Rail Transportation	160 000	150 000	130 000	98 000	88 000	93 000	93 000	94 000	88 000
Tire Wear and Brake Lining	-	-	-	-	-	-	-	-	-

Agriculture (tonnes)
Sector	1990	2000	2005	2015	2016	2017	2018	2019	2020
Sub-total	2 100	2 200	2 100	2 700	2 900	2 800	2 800	2 900	2 600
Animal Production	-	-	-	-	-	-	-	-	-
Crop Production	-	-	-	-	-	-	-	-	-
Agricultural Fuel Combustion	2 100	2 200	2 100	2 700	2 900	2 800	2 800	2 900	2 600

Commercial/Residential/Institutional (tonnes)
Sector	1990	2000	2005	2015	2016	2017	2018	2019	2020
Sub-total	74 000	78 000	76 000	72 000	70 000	74 000	77 000	75 000	71 000
Commercial and Institutional Fuel Combustion	23 000	30 000	30 000	26 000	27 000	29 000	29 000	31 000	30 000
Commercial Cooking	-	-	-	-	-	-	-	-	-
Construction Fuel Combustion	3 900	2 000	2 700	2 500	2 600	2 700	2 800	3 000	3 000
Home Firewood Burning	13 000	11 000	9 300	12 000	12 000	12 000	11 000	10 000	9 100
Human	-	-	-	-	-	-	-	-	-
Marine Cargo Handling	0.20	0.059	-	26	24	28	26	38	18
Residential Fuel Combustion	35 000	35 000	35 000	31 000	29 000	31 000	33 000	31 000	29 000
Service Stations	-	-	-	-	-	-	-	-	-
Other (Miscellaneous)	-	-	-	-	-	-	-	-	-

Incineration and Waste (tonnes)
Sector	1990	2000	2005	2015	2016	2017	2018	2019	2020
Sub-total	7 200	7 200	8 500	4 300	4 500	5 700	4 900	4 900	4 500
Crematoriums	55	78	99	150	150	160	170	170	180
Waste Incineration	2 700	2 800	3 600	2 300	2 500	2 800	2 600	2 600	2 500
Waste Treatment and Disposal	4 500	4 300	4 800	1 800	1 800	2 700	2 100	2 100	1 800

Paints and Solvents (tonnes)
Sector	1990	2000	2005	2015	2016	2017	2018	2019	2020
Sub-total	110	120	130	23	23	17	15	22	26
Dry Cleaning	1.1	1.6	-	-	-	-	-	-	-
General Solvent Use	-	-	-	-	-	-	-	-	-
Printing	110	120	130	23	23	17	15	20	19
Surface Coatings	0.12	0.12	-	-	-	-	-	1.9	6.4

Dust (tonnes)
Sector	1990	2000	2005	2015	2016	2017	2018	2019	2020
Sub-total	-	-	-	-	-	-	-	-	-
Coal Transportation	-	-	-	-	-	-	-	-	-
Construction Operations	-	-	-	-	-	-	-	-	-
Mine Tailings	-	-	-	-	-	-	-	-	-
Paved Roads	-	-	-	-	-	-	-	-	-
Unpaved Roads	-	-	-	-	-	-	-	-	-

Fires (tonnes)
Sector	1990	2000	2005	2015	2016	2017	2018	2019	2020
Sub-total	7 500	1 400	890	2 000	1 700	990	600	670	530
Prescribed Burning	7 400	1 400	850	2 000	1 600	970	570	650	500
Structural Fires	49	39	36	27	27	27	28	27	30

Totals (tonnes)
Sector	1990	2000	2005	2015	2016	2017	2018	2019	2020
Ore and Mineral Industry	100 000	99 000	110 000	81 000	77 000	86 000	82 000	80 000	74 000
Oil and Gas Industry	350 000	460 000	430 000	480 000	470 000	480 000	490 000	480 000	450 000
Electric Power Generation (Utilities)	260 000	330 000	250 000	150 000	150 000	140 000	130 000	120 000	100 000
Manufacturing	190 000	170 000	140 000	69 000	68 000	69 000	69 000	67 000	63 000
Transportation and Mobile Equipment	1 300 000	1 600 000	1 200 000	750 000	710 000	740 000	770 000	770 000	680 000
Agriculture	2 100	2 200	2 100	2 700	2 900	2 800	2 800	2 900	2 600
Commercial/Residential/Institutional	74 000	78 000	76 000	72 000	70 000	74 000	77 000	75 000	71 000
Incineration and Waste	7 200	7 200	8 500	4 300	4 500	5 700	4 900	4 900	4 500
Paints and Solvents	110	120	130	23	23	17	15	22	26
Dust	-	-	-	-	-	-	-	-	-
Fires	7 500	1 400	890	2 000	1 700	990	600	670	530
Grand Total	2 300 000	2 700 000	2 300 000	1 600 000	1 600 000	1 600 000	1 600 000	1 600 000	1 400 000

Note:
Refer to Annex 4.4 for more information on international marine navigation and air transportation reporting emissions.

Other emissions estimated in the APEI (tonnes)
Sector	1990	2000	2005	2015	2016	2017	2018	2019	2020
Domestic Air Transportation (Cruise)	28 000	26 000	27 000	30 000	31 000	33 000	35 000	36 000	19 000
International Air Transportation (Cruise)	23 000	39 000	44 000	56 000	61 000	68 000	78 000	80 000	36 000
International Marine Navigation	81 000	120 000	130 000	120 000	120 000	110 000	110 000	110 000	91 000

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Canada’s Air Pollutant Emissions Inventory Report 2022: chapter 2.3

2.3 Nitrogen oxides (NO_x)

Figure 2–3: Trends in Canadian NO_x emissions (1990 to 2020)

Table 2–5: National summary of annual NO_x emissions

Page details

Canada’s Air Pollutant Emissions Inventory Report 2022: chapter 2.3

2.3 Nitrogen oxides (NOx)

Figure 2–3: Trends in Canadian NOx emissions (1990 to 2020)

Table 2–5: National summary of annual NOx emissions

Page details

2.3 Nitrogen oxides (NO_x)

Figure 2–3: Trends in Canadian NO_x emissions (1990 to 2020)

Table 2–5: National summary of annual NO_x emissions