Growing Risks Ahead - Energy and Climate: How to Achieve a Successful Energy Transition - page 16

Effects of energy consumption on the environment at local
and regional levels

Energy consumption results in emissions of pollutants. Local pollution,
characteristic of urban areas or caused by emissions from an industrial
plant (factory, cement works, refinery, etc.), is converted into regional
pollution through accumulation of pollutants in the atmosphere.
Pollution becomes global when it concerns the entire planet, a situation
we are facing with the greenhouse gas effect.
Local pollution in an urban environment is duemainly to transport. The
main pollutants discharged by automotive vehicles are carbon monoxide,
unburnt hydrocarbons, nitrogen oxides and particulates.
High contents of nitrogen oxides and unburnt hydrocarbons in the
atmosphere favour photochemical reactions which occur in the presence
of high solar radiation, and therefore mainly in summer. These reactions
result in the formation of ozone and other oxidising compounds (hydro-
gen peroxide, aldehydes, peroxyacetylnitrate or PAN). The ozone which
therefore forms in the lower atmospheric layers (tropospheric ozone) is
irritating and noxious to breathe. It has an adverse effect on health,
especially on the respiratory system, as well as on the environment since it
attacks vegetation, thereby acting as a pollution indicator, unlike the
ozone present in the higher atmospheric layers (stratospheric ozone)
which protects against excessive ultraviolet radiation and which must
be preserved.
The fine particulates emitted in particular by diesel engine vehicles
represent a source of pollution which is especially serious in urban areas.
Particulates with diameters less than 10 m (PM 10 ) are taken into account

when analysing atmospheric pollution. Particulates with diameters less
than 2.5

m

m (PM 2.5 ) seem to be the most dangerous. The finest particu-
lates, with diameters between 0.01

m

m, penetrate deeply into
the respiratory tracts, into the pulmonary alveoli, from where they are
only eliminated very slowly provided that exposure to the pollution is not
permanent, causing pulmonary and cardiac risks. Pollutants adsorbed on
the particulates also penetrate into the organism via this pathway.
In addition, some aromatic organic compounds (benzene), polycyclic
compounds (PAHs) and aldehydes (e.g. formaldehyde) emitted by auto-
mobiles are potentially carcinogenic. In the industrialised countries (USA,
European countries, Japan), significant progress has been made in the
reduction of pollutant emissions, through the introduction of increasingly
stringent standards for new vehicles.

m m and 0.1 m