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Lasek, J.A.;  Lajnert, R. Dualistic Nature of NOx Impact on Greenhouse Effect. Encyclopedia. Available online: (accessed on 09 December 2023).
Lasek JA,  Lajnert R. Dualistic Nature of NOx Impact on Greenhouse Effect. Encyclopedia. Available at: Accessed December 09, 2023.
Lasek, Janusz Andrzej, Radosław Lajnert. "Dualistic Nature of NOx Impact on Greenhouse Effect" Encyclopedia, (accessed December 09, 2023).
Lasek, J.A., & Lajnert, R.(2022, November 03). Dualistic Nature of NOx Impact on Greenhouse Effect. In Encyclopedia.
Lasek, Janusz Andrzej and Radosław Lajnert. "Dualistic Nature of NOx Impact on Greenhouse Effect." Encyclopedia. Web. 03 November, 2022.
Dualistic Nature of NOx Impact on Greenhouse Effect

Nitrogen oxides (NOx = NO + NO2) emitted from a stationary combustion chamber (including waste to energy plants) or engines cause numerous undesirable environmental effects. These include negative influences on human and animal health, detrimental effects on plants and vegetation, acid rain, and smog. These negative influences are commonly accepted by the scientific community. However, the impact of NOx on the greenhouse effect (GHE) is not generally accepted by the scientific community.

NOx greenhouse effect (GHE) indirect greenhouse gas direct greenhouse gas

1. Introduction

It has already been mentioned that global warming potential (GWP) can be negative or positive. Indeed, the warming and cooling effect of NOx in the atmosphere is highlighted in the literature [1][2][3]. The nature of this effect depends on the mentioned parameters such as NOx source, horizontal and vertical location, and the co-existence of other compounds. In the next section, an explanation of the cooling and/or warming nature of NOx is provided.

2. Warming Nature

The presence of NOx can influence global warming. The results of investigations suggest that the main process responsible for this effect is the impact of NOx on the conversion of tropospheric ozone (O3) [4], which is recognized as a GHG [5]. Depending on the concentration of NOx in the atmosphere and the equilibrium between other compounds contained in the atmosphere, O3 can either be created or destroyed. If the concentration of NOx are higher than the range of 10–30 pptv (parts-per-trillion (volumetric), 10−12), O3 can be created in the atmosphere. Furthermore, the rate of O3 creation because of the presence of NOx depends on the latitudes and seasons [4]. Namely, it has been postulated that the presence of NOx (NO/NO2) influences the catalytic conversion of O3, according to the following reactions ((2)–(5)) [6]:
OH + CO + O2 → CO2 + HO2     
HO2 + NO → NO2 + OH           
NO2 + hν → NO + O(3P)         
O(3P) + O2 + M → O3 + M       
Summarizing reactions (2)–(5), the overall process reaction (6) is
CO + 2O2 + hν → CO2 + O3     
Thus, this proves and provides clear evidence that the presence of NOx causes the creation of O3 and CO2 under sunlight irradiation. Hence, they influence global warming because of the creation of GHGs. The effect of the presence of NOx on O3 conversion in the atmosphere was confirmed by Renyi Zhang, Xuexi Tie, and Donald W. Bond [7].
Another phenomenon potentially influencing global warming due to the presence of NOx is their impact on N2O conversion [4][8]. Namely, NOx emitted into the atmosphere can be converted into N2O (a direct GHG) in the complex processes occurring in the soil. The simplified description of this complex mechanism of converting NOx into N2O is as follows: Emitted NO is transformed into NO2, and next to nitrogen acids and other compounds in the form of aerosols. These compounds are then transferred into the soil by precipitation. Further transformation in the soil (such as by the denitrification process) leads to incidental emissions of N2O from the soil to the atmosphere. It was estimated that the N2O emissions from soil (as a consequence of NOx transformation) are 1.2%–3.6% of the total N2O emissions from other sources [4]. Nevertheless, understanding the soil N cycling processes is still being discussed [9].

3. Cooling Nature

It was previously mentioned that the presence of NOx can lead (in some specific conditions) to global cooling. This is why the GWP values are sometimes negative. Furthermore, NOx are sometimes termed as cooling gases [10][11][12][13]. It was proven that the presence of NO can influence the increase in the concentration of OH radicals in the atmosphere, and OH radicals contribute to destroying methane, according to the following reactions [12]:
HO2 + NO ↔ OH + NO2   
OH + CH4 ↔ H2O + CH3   
Here, CH4 belongs to the direct group of GHGs, thus destroying it causes a cooling effect. Moreover, CH4 reduction results in a long-term reduction in tropospheric O3, and a long-term reduction in stratospheric water vapor from the reduced oxidation of CH4. Both of these phenomena are recognized as negative radiative forcing effects [14]. It should be explained that the cooling effect of NOx depends on the impact of other compounds existing in the atmosphere. Namely, the presence of CO can contribute to a decrease in the concentration of OH radicals. Consequently, the cooling effect of NOx can be inhibited, and the GWP for NOx is positive (a warming effect). Furthermore, the decrease in the OH concentration inhibits CH4 destruction (being a direct GHG). If the impact of NOx is considered without reference to the CO contribution, it would only be assumed that the cooling effect of NOx is from surface sources. The increase in the CO concentration in the atmosphere causes NOx to convert from cooling gases to warming gases with a positive GWP [13]. One can have reasonable hope that the development of combustion technology by increasing the combustion efficiency and decreasing CO emissions will inhibit NOx from having an effect as a warming gas.
Another phenomenon responsible for the cooling effect of NOx is the formation of aerosols (dispersion of very fine liquid droplets) in the atmosphere. Increased aerosol formation and cloud reflectivity cause a decrease in sunlight radiation and enhance the cooling effect [4][10]. The main process responsible for aerosol formation is the conversion of SO2 into H2SO4 formations, which condensate as very fine droplets (aerosols). The contribution of NOx in this process relies on OH formation. It has already been explained that an increase in NO concentration causes an increase in OH radical concentration in the atmosphere. Moreover, the presence of OH radicals intensifies SO2 conversion into aerosols, thus directly causing a cooling effect [10].

4. Summary

It has already been mentioned that the warming and cooling effects of NOx in the atmosphere are possible due to the impact of different processes. The warming and cooling effects are summarized in Table 1. These effects were divided into three groups in terms of the influence area (i.e., air, water, soil, and vegetation aboveground). Some processes seem to be opposing. Thus, examples of these cases are described in a “cross-impact” column.
Table 1. The summary of the warming and cooling effect of NOx in terms of the influence on the area.


  1. Butterbach-Bahl, K.; Nemitz, E.; Zaehle, S.; Billen, G.; Boeckx, P.; Erisman, J.; Garnier, J.; Upstill-Goddard, R.; Kreuzer, M.; Oenema, O. Nitrogen as a Threat to the European Greenhouse Balance in: The European Nitrogen Assessment; Sutton, M.A., Howard, C.M., Erisman, J.W., Billen, G., Bleeker, A., Grennfelt, P., van Grinsven, H., Grizzetti, B., Eds.; Cambridge University Press: Cambridge, UK, 2011.
  2. Pinder, R.W.; Bettez, N.D.; Bonan, G.B.; Greaver, T.L.; Wieder, W.R.; Schlesinger, W.H.; Davidson, E.A. Impacts of human alteration of the nitrogen cycle in the US on radiative forcing. Biogeochemistry 2013, 114, 25–40.
  3. Mahashabde, A.; Wolfe, P.; Ashok, A.; Dorbian, C.; He, Q.; Fan, A.; Lukachko, S.; Mozdzanowska, A.; Wollersheim, C.; Barrett, S.R.H.; et al. Assessing the environmental impacts of aircraft noise and emissions. Prog. Aerosp. Sci. 2011, 47, 15–52.
  4. Lammel, G.; Graßl, H. Greenhouse effect of NOx. Environ. Sci. Pollut. Res. 1995, 2, 40–45.
  5. Mitchell, J.F. The “greenhouse” effect and climate change. Rev. Geophys. 1989, 27, 115–139.
  6. Ehhalt, D.; Prather, M.; Dentener, F.; Derwent, R.; Dlugokencky, E.J.; Holland, E.; Isaksen, I.; Katima, J.; Kirchhoff, V.; Matson, P.; et al. Atmospheric Chemistry and Greenhouse Gases; Pacific Northwest National Laboratory (PNNL): Richland, WA, USA, 2001.
  7. Zhang, R.; Tie, X.; Bond, D.W. Impacts of anthropogenic and natural NOx sources over the U.S. on tropospheric chemistry. Proc. Natl. Acad. Sci. USA 2003, 100, 1505–1509.
  8. Gutiérrez, M.; Biagioni, R.N.; Alarcón-Herrera, M.T.; Rivas-Lucero, B.A. An overview of nitrate sources and operating processes in arid and semiarid aquifer systems. Sci. Total Environ. 2018, 624, 1513–1522.
  9. Butterbach-Bahl, K.; Baggs, E.M.; Dannenmann, M.; Kiese, R.; Zechmeister-Boltenstern, S. Nitrous oxide emissions from soils: How well do we understand the processes and their controls? Philos. Trans. R. Soc. B Biol. Sci. 2013, 368, 20130122.
  10. Lawrence, M.G.; Crutzen, P.J. Influence of NOx emissions from ships on tropospheric photochemistry and climate. Nature 1999, 402, 167–170.
  11. Fuglestvedt, J.S.; Isaksen, I.S.A.; Wang, W.-C. Estimates of indirect global warming potentials for CH4, CO and NOx. Clim. Chang. 1996, 34, 405–437.
  12. Johnson, C.E.; Derwent, R.G. Relative radiative forcing consequences of global emissions of hydrocarbons, carbon monoxide and NOx from human activities estimated with a zonally-averaged two-dimensional model. Clim. Chang. 1996, 34, 439–462.
  13. Wild, O.; Prather, M.J.; Akimoto, H. Indirect long-term global radiative cooling from NOx emissions. Geophys. Res. Lett. 2001, 28, 1719–1722.
  14. Skowron, A.; Lee, D.S.; De León, R.R. Variation of radiative forcings and global warming potentials from regional aviation NOx emissions. Atmos. Environ. 2015, 104, 69–78.
  15. Adouani, N.; Limousy, L.; Lendormi, T.; Sire, O. N2O and NO emissions during wastewater denitrification step: Influence of temperature on the biological process. Comptes Rendus Chim. 2015, 18, 15–22.
  16. Kimochi, Y.; Inamori, Y.; Mizuochi, M.; Xu, K.-Q.; Matsumura, M. Nitrogen removal and N2O emission in a full-scale domestic wastewater treatment plant with intermittent aeration. J. Ferment. Bioeng. 1998, 86, 202–206.
  17. Hu, Z.; Zhang, J.; Xie, H.; Li, S.; Zhang, T.; Wang, J. Identifying sources of nitrous oxide emission in anoxic/aerobic sequencing batch reactors (A/O SBRs) acclimated in different aeration rates. Enzym. Microb. Technol. 2011, 49, 237–245.
  18. Negoro, M.; Shioji, N.; Miyamoto, K.; Micira, Y. Growth of microalgae in high CO2 gas and effects of SOx and NOx. Appl. Biochem. Biotechnol. 1991, 28, 877.
  19. Li, T.; Xu, G.; Rong, J.; Chen, H.; He, C.; Giordano, M.; Wang, Q. The acclimation of Chlorella to high-level nitrite for potential application in biological NOx removal from industrial flue gases. J. Plant Physiol. 2016, 195, 73–79.
  20. Paerl, H.W.; Scott, J.T. Throwing fuel on the fire: Synergistic effects of excessive nitrogen inputs and global warming on harmful algal blooms. Environ. Sci. Technol. 2010, 44, 7756–7758.
  21. El-Shehawy, R.; Gorokhova, E.; Fernandez-Pinas, F.; del Campo, F.F. Global warming and hepatotoxin production by cyanobacteria: What can we learn from experiments? Water Res. 2012, 46, 1420–1429.
  22. Wagner, C.; Adrian, R. Cyanobacteria dominance: Quantifying the effects of climate change. Limnol. Oceanogr. 2009, 54, 2460–2468.
  23. Kumar, K.; Dasgupta, C.N.; Nayak, B.; Lindblad, P.; Das, D. Development of suitable photobioreactors for CO2 sequestration addressing global warming using green algae and cyanobacteria. Bioresour. Technol. 2011, 102, 4945–4953.
  24. Wang, C.; Yu, X.; Lv, H.; Yang, J. Nitrogen and phosphorus removal from municipal wastewater by the green alga Chlorella sp. J. Environ. Biol. 2013, 34, 421.
  25. Yen, H.-W.; Ho, S.-H.; Chen, C.-Y.; Chang, J.-S. CO2, NOx and SOx removal from flue gas via microalgae cultivation: A critical review. Biotechnol. J. 2015, 10, 829–839.
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