The role of public-private partnership investment and eco-innovation in environmental abatement in USA: evidence from quantile ARDL approach

The current research investigates the role of public-private partnership investment (PPPI) and ecological innovation (ECO) along with economic growth on the environmental abatement (i.e., carbon dioxide emission, particulate matters 2.5) in the USA. Quantile autoregressive lagged (QARDL) method was employed during the study period of 1990-2015. The study findings confirm that under long-run estimation, GDP and PPPI are causing more environmental abatement in the form of CO2 emission and haze pollution like PM2.5. The factors like ecological innovation and GDP2 are playing their role towards lowering the CO2 emission and PM2.5 under different quantiles. Furthermore, it is observed that under short-run estimation, past values of the carbon emissions and PM2.5 have their significant and positive relationship with their current values. Besides, the findings through Wald test estimation confirm that parameter constancy of the speed of adjustment parameter is rejected at 1% significance level for the CO2 emission and haze pollution like PM2.5 in USA. Besides, present study also provides some policy implications.