The sustainable potential of efficient air-transportation industry and green innovation in realising environmental sustainability in G7 countries

Figures & data

Figure 1. G-7 countries annual air transportation CO₂ emission. Source: OECD. Stat Data set of Air transportation carbon emission.

Figure 2. Annual exposure of fine particulate matter (PM_2.5) of G-7 countries. Source: OECD. Stat Data set of exposure to Fine particulate matter (PM_2.5) data aggregated from over 80,000 data points.

Table 1. Data description.

Variables	Symbols	Definition & measures	Data source
Environmental degradation	CE	Carbon emission measured in metric tons	OECD statistics
Eco-innovation	ECO	Environmental related technologies % of total technologies measured in terms of patents.	OECD statistics
Air quality	PM2.5	Annual Fine Particulate Matter (PM2.5) concentration of G7 countries. measure in microgram per cubic meter (µg/m^3)	OECD statistics
Economic growth	GDP	Real Gross Domestic Product per capita measured in constant US Dollar (Base year 2010 = 100)	WDI
EKC hypothesis	GDP^2	Quadric term of GDP per capita measured in constant US Dollar (Base year 2010 = 100)	WDI

WDI: World development indicator.

OECD: Organization of economic co-operation and development.

Source: generated by authors.

Table 2. Results of cross-sectional dependence analysis.

Variable	Test statistics (p-values)
CE	16.212*** (0.000)
PM2.5	19.121*** (0.000)
GDP	15.231*** (0.000)
GDP^2	18.301*** (0.000)
TRA	22.231*** (0.000)
ECO	17.123*** (0.000)

Note: ***, ** & * explain the level of significance at 1%, 5% and 10%, respectively, whereas the values are in parentheses contains p-values.

Source: generated by authors.

Table 3. Results of unit root test with & without structural break Pesaran (2007).

	Level I(0)			First difference I(1)
Variables	CIPS	M-CIPS		CIPS		M-CIPS
CE	−3.025***	−7.018**		–		–
PM2.5	−5.002***	−6.001**		–		–
GDP	−4.012***	−8.101**		–		–
GDP^2	−5.001***	−6.021**		–		–
TRA	−3.011***	−7.102**		–		–
ECO	−4.102***	−7.121**		–		–
Bai and Carrion-I-Silvestre (2009)
	Z	Pm	P	Z	Pm	P
CE	0.447	0.835	21.149	−5.036***	6.215***	66.154***
PM2.5	0.529	0.733	17.148	−4.006***	5.556***	73.058***
GDP	0.449	0.531	24.365	−5.657***	6.059***	96.187***
GDP^2	0.564	0.672	16.176	−5.067***	6.389***	67.089***
TRA	0.538	0.856	19.765	−4.561***	5.005***	83.058***
ECO	0.429	0.732	17.048	−5.005***	6.556***	74.058***

Note: The level of significance is determined by 1%, 5%, and 10% indicated through ***, ** and *, respectively. For Bai and Carrion-I-Silvestre (2009) test, 1%, 5% and 10% critical values (CV) for Z and Pm statistics are 2.326, 1.645 and 1.282 while the critical values (CV) for P are 56.06, 48.60 and 44.90, separately.

Source: generated by authors.

Table 4. Results of slope heterogeneity analysis.

Statistics	Test value (p-value)
Dependent variable: CE
Delta tilde	57.289*** (0.000)
Delta tilde Adjusted	63.357*** (0.000)
Dependent variable: PM2.5
Delta tilde	38.299*** (0.000)
Delta tilde Adjusted	41.267*** (0.000)

Note: ***, ** & * explain the level of significance at 1%, 5% and 10%, respectively, whereas the values are in parentheses contains p-values.

Source: generated by authors.

Table 5. Results of Westerlund and Edgerton (2008) panel cointegration analysis.

Test	No break	Mean shift	Regime shift
Dependent variable: CE
Zφ(N)	−4.234***	−3.901***	−5.021***
Pvalue	0.000	0.000	0.000
Zτ(N)	−3.123***	−2.910***	−4.001***
Pvalue	0.000	0.000	0.000
Dependent variable: PM2.5
Zφ(N)	−3.357***	−2.951***	−4.101***
Pvalue	0.000	0.000	0.000
Zτ(N)	−4.789***	−3.347***	−5.100***
Pvalue	0.000	0.000	0.000

Note: ***, ** & * explain the level of significance at 1%, 5% and 10%, respectively, whereas the values are in parentheses contains p-values.

Source: generated by authors.

Table 6. Results of Banerjee and Carrion‐i-Silvestre (2017) cointegration analysis.

Countries	No deterministic specification	With constant	With trend
Dependent variable: CE emission
Full sample	−5.245***	−4.658***	−6.983***
France	−6.504***	−5.325***	−7.396***
Germany	−4.871***	−3.889***	−5.256***
Italy	−7.695***	−6.658***	−8.358***
Japan	−5.204***	−4.474***	−6.387***
United States	−4.007***	−3.555***	−5.287***
United Kingdom	−6.774***	−5.822***	−7.389***
Canada	−7.336***	−6.451***	−8.001***
Dependent variable: PM2.5 emission
Full sample	−4.872***	−3.761***	−5.123***
France	−3.285***	−3.174***	−4.321***
Germany	−5.145***	−4.034***	−6.124***
Italy	−6.247***	−5.136***	−7.204***
Japan	−4.276***	−3.165***	−5.301***
United States	−3.176***	−3.065***	−4.105***
United Kingdom	−4.134***	−3.303***	−5.010***
Canada	−5.278***	−4.167***	−6.202***

Note: Critical Value (CV) at 5%** and 10%* with constant is −2.32, −2.18 and with trend is −2.92 and −2.82.

Source: generated by authors.

Table 7. Results of CS-ARDL analysis (Long run CS-ARDL results).

Variables	Coefficients	t-statistics	p-values
Dependent variable: CE
GDP	0.311***	4.011	0.000
GDP2	−0.284*	−1.707	0.088
TRA	−0.253***	−3.171	0.000
ECO	−0.264**	−2.012	0.045
CSD-Statistics	–	0.044	0.601
Dependent variable: PM2.5
GDP	0.269***	5.011	0.000
GDP2	−0.350***	−3.006	0.000
TRA	−0.173*	−1.896	0.056
ECO	−0.312***	−3.426	0.000
CSD-statistics	–	0.013	0.820

Note: ***, ** & * explain the level of significance at 1%, 5% and 10%, respectively.

Source: generated by authors.

Table 8. Results of CS-ARDL analysis (short run CS-ARDL results).

Variables	Coefficients	t-statistics	p-values
Dependent variable: CE
GDP	0.097***	3.087	0.000
GDP2	−0.039***	−4.101	0.000
TRA	−0.171***	−3.843	0.000
ECO	−0.073***	−5.441	0.000
ECT(-1)	−0.212***	−4.003	0.000
Dependent variable: PM2.5
GDP	0.129***	6.062	0.000
GDP2	−0.019	−1.541	0.189
TRA	−0.023***	−3.033	0.000
ECO	−0.086***	−3.577	0.000
ECT(-1)	−0.254***	−5.381	0.000

Note: ***, ** & * explain the level of significance at 1%, 5% and 10%, respectively.

Source: generated by authors.

Table 9. Results of AMG & CCEMG for robustness check.

	Augmented Mean Group (AMG)			Common Correlated Effect Mean Group (CCEMC)
Dependent variables CE	Coefficients	t-statistics	p-values	Coefficients	t-statistics	p-values
GDP	0.156***	5.010	0.000	0.238***	5.201	0.000
GDP2	−0.058***	−3.105	0.000	−0.158***	−6.548	0.000
TRA	−0.237***	−4.658	0.000	−0.364***	−3.884	0.000
ECO	−0.402***	−5.985	0.000	−0.341***	−5.569	0.000
Wald test	–	23.310	0.000	−	14.075	0.000
Dependent variable PM2.5
GDP	0.251***	−7.010	0.000	0.103***	5.651	0.000
GDP2	−0.168***	−3.955	0.000	−0.062***	−4.025	0.000
TRA	−0.247***	−5.121	0.000	−0.208***	−6.211	0.000
ECO	−0.302***	−5.573	0.000	−0.342***	−4.846	0.000
Wald test	−	36.874	0.000	−	15.050	0.000

Note: ***, ** & * explain the level of significance at 1%, 5% and 10%, respectively.

Source: generated by authors.

Pesaran, M. H. (2007). A simple panel unit root test in the presence of cross‐section dependence. Journal of Applied Econometrics, 22(2), 265–312. https://doi.org/10.1002/jae.951

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