For the purpose of comparison it should be specified that emissions from transport of another major greenhouse gas, namely methane, for the period from 1995 through 2001 were within the range of 0,21 and 0,36 % of the total quantity of methane emissions from all anthropogenic sources, while for 2001 they only represent 0,22 %.

Observations reveal that regions having serious environmental problems, including poor ambient air quality, labelled as “hot spots”, are in the majority of cases cities with intense car traffic, such as Sofia, Bourgas, Plovdiv, Varna etc. where the car traffic substantially contributes to air pollution. Data supplied by monitoring stations located within areas with intense car traffic show harmful substances concentrations that are several times higher, due to motor vehicles as compared to areas with normal traffic. The quantity of nitrogen oxides, carbon monoxide, and non-methane volatile organic compounds emitted is the largest, and the leading part is caused by emission from the road transport (see the figures).

The analysis of data on the total yearly emissions of the main pollutants shows that with regard to lead emissions the contribution of the transport sector and the road transport in particular to the total quantities of lead emitted is considerable. This is due to the still significant share held by leaded petrol into the overall petrol consumption in the country amounting 33 %. Lead emissions from the road transport for 2001 were considerably reduced as compared to the previous year as a result of the consumption of unleaded petrol which has increased from 249 141 tons for 2000 to 380 161 tons for 2001(see the figure below). This represents 18,8 % of the total quantity of lead emitted from different anthropogenic sources (industry, energy sector etc.) compared to 30,5 % for 2000. The distribution in percentages of the total yearly emissions from the transport sector with regard to the main pollutants for the period from 1995 through 2001 ranges from the average of 43,6 % from nitrogen oxides, 39,2 % from lead and 38,3 % from non-methane volatile organic compounds emitted by different anthropogenic sources. As can be seen on the graphics, sulphur dioxide emissions from the transport sector are insignificant. figure

Poor quality and considerable ambient air pollution in the so called “hot spots” is to a great extent due to the continuous increment added by the automobile fleet (see the figure).

Available data shows that in 2001 the total number of motor vehicles registered marked a 19,8 % increase compared to 1995 and the increase was 3,7 % as compared to 2000. In 2001 the portion of motor vehicles registered increased to 26,6 % as compared to 1995 and the total numbers of trucks and buses increased to 21,0 % and 4,5 % respectively. There was an increase of the shares of motorcars, trucks and buses of 4,7 %, 3,5 % and 1,3 % respectively as compared to 2000. The issue of ambient air pollution by motor vehicles is more problematic due to the fact that the vehicle fleet of the country is characterized by an exceptionally unfavourable age structure. Over 59 % of motor vehicles on the road were manufactured more than 15-20 years ago.

According to data supplied by the Bulgarian Car Importers Union only 10-12 % of all motor vehicles registered annually are new ones, which is the result of low purchasing capacity of the public. There is still a trend that around 90 % of all newly registered are second hand (see Table).

Year	First registration		New motor vehicles, %	End-of-life motor vehicles*	Annual increase
Year	*New and second hand motor vehicles - total**	New motor vehicles**	New motor vehicles, %	End-of-life motor vehicles*	Annual increase
1996	87977	7600	8,6	15287	72690
1997	37558	7797	20,8	13444	24114
1998	100634	12362	12,3	18734	81900
1999	122665	11958	9,7	17663	105002
2000	108037	13069	12,1	18938	89099
2001	128681	13365	10,4	25915	102766

**New motor vehicles sold in the country, based on data supplied by the Bulgarian Car Importers Union

Public bus transport also significantly contributes to ambient air pollution within settlements due to the outdated and worn-out fleet. A majority of the buses in service use are still IKARUS-280 manufactured over 15 ago. So to this end, constant efforts are made to improve ecological parameters of bus engines in order to reduce the harmful substances contained in exhaust gases. Along these lines, partial renovation of the Sofia bus fleet with new engines meeting the European standards and reconstruction of bus engines for operation on two types of fuel, namely natural gas and diesel fuel, has been carried out several times with the financial aid of the PHARE Programme and the National Environmental Protection Fund (NEPF). In 2001 the Ministry of Environment and Water launched the Project “Limiting the Negative Impact of Exhaust Gases from the Sofia Public Bus Transport” financed by the PHARE Programme and carried out with the aid of the Sofia Municipality. Within the scope of this project, 50 new diesel engines and 19 engines operating on natural gas and diesel fuel, to be installed on IKARUS-280 buses, property of CCPT Autotransport JSC, have been supplied. In addition, new natural gas compressor module and emission parameters control equipment have also been supplied. The overall cost was 2 262 761 euro.

With regard to the share of other types of transport in causing ambient air pollution (according to data supplied by the Ministry of Transport and Communications) it may be noted that emissions of harmful substances from railway transport do not exceed 1,5 % of those from the road transport. The high level of railway electrification covering over 60 % of the whole railway network has indisputably contributed to that. The share of water transport is also insignificant. With regard to air transport the potential health and ecological impacts of noise and air pollution are focused on a local scale, namely areas in the vicinity of airports.

The considerable impact of the transport sector on all environmental components, and ambient air quality in particular, determines this issue as one of the main priorities in pursuing the ecological policy under the National Environmental Strategy and the Action Plan adopted by Decision No 455 of 20 June 2001.