Air pollution - Drivers and pressures (Belgium)

Ozone precursors (NOx and VOC) emissions, expressed in TOFP (Total Ozone Formation Potential) units decreased by 40 % between 1990 and 2007. Because the different ozone precursors have a different share in the tropospheric ozone formation, the photochemically relevant sum of the precursors is expressed in TOFP units. Besides NOx and VOC, CO and CH4 also play a role in the photochemical ozone formation reactions. Their role, however, is less important and the TOFP used here is only the relevant sum of NOx and VOC.

The VOC emissions have decreased more significantly than the NOx emissions. VOC emissions decreased by more than 50 %, and NOx emissions only by 30 % between 1990 and 2007. The NEC (National Emission Ceiling) target for 2010 for VOC is within reach. The NOx target, however, is totally out of reach. It is estimated (EEA, 2009) that the Belgian NOx emissions in 2010 will be around 43 % higher than the target. The main reason is the increasing share of diesel fueled cars in the Belgian vehicle fleet (see hereunder). Diesel cars emit significantly more NOx than gasoline and LPG cars. Almost 80 % of new cars sold in Belgium are diesel cars now. This is further stimulated by the Belgian government due to ’environmental‘ subsidies that are given only on the basis of CO2 emissions. Diesel cars generally emit less CO2 than comparative gasoline cars so that only diesel cars (with the exception of very small gasoline and hybrid cars) are eligible for these subsidies. Another reason for the increasing share of diesel cars is the lower taxes which makes diesel cheaper (per liter) than gasoline.