Environmental Engineering Reference
In-Depth Information
dif erences. Their i ndings showed a reasonable EKC relationship between
the country GDP and CO
2
emissions. Under the Gamma functional form,
the turning points were $13 260 for all countries, $17 868 for non-OECD
countries and $15 582 for OECD countries, while under the Weibull func-
tional form, they were $13648, $17079 and $15709, respectively. They
concluded that when using non-nested tests and applying new functional
forms, such as the Gamma and Weibull, to describe the reduced-form rela-
tionship between GDP and CO
2
emissions, the emergence of a bell-shaped
EKC was possible with reasonable turning points.
In a recent study, Cavlovic et al. (2000) conducted a statistical meta-
analysis to synthesis the results of 25 existing EKC studies, with over 120
observations, and calculated new income turning points (ITPs) for 11 dif-
ferent pollutants to determine whether credible conclusions from previous
studies could be made. These pollutant categories were toxic emissions,
urban air quality, deforestation, heavy particulates, urban quality, water
quality/pollution, heavy metals, SO
2
, combustion by-products, hazardous
waste and CO
2
. They found the new ITPs ranged from $3020 for toxic
emissions to $199 345 for CO
2
. They concluded that (1) ITP results were
not necessarily representative across nations as their ITPs were higher
than those of previous studies for developed countries, (2) ITPs for emis-
sions and ambient concentrations of a particular pollutant were not com-
parable, (3) inclusion of trade ef ects variable, rather than income alone,
would tend to increase the ITPs and (4) methodological choices would
signii cantly af ect the magnitude of ITPs.
In a study by Hettige et al. (1997) on water pollution, they examined
the relationship between economic development and industrial water pol-
lution. They used panel data collected at the factory level from national
and regional environmental protection agencies (EPAs) in 13 countries:
Brazil, China, India, Korea, Finland, Indonesia, Mexico, the Netherlands,
the Philippines, Sri Lanka, Taiwan, Thailand and the United States of
America. They basically tested the ef ect of income growth on three deter-
minants of pollution: the share of industry in total output, the industry
composition/share of polluting sectors and end-of-pipe pollution abate-
ment. In order to test the impact of regulation on the demand for labour,
they did a complementary study where they added a measure of regulatory
strictness to cross-country labour intensity. They found evidence of EKC
for the manufacturing share only. The sectoral composition improved to
middle-income level and then stabilized, while end-of-pipe pollution inten-
sity strongly declined with growth of income. They attributed these results
to (1) the application of stricter regulations as income increased and (2)
the complementarity of pollution and labour in production. The results
of their study also showed that income elasticities for both the pollution
