Table 1

Modelled average traffic contribution along HTRs (>10 000 vehicles circulating per day) to the annual average of NO₂ and PM₁₀ concentrations (in micrograms per cubic metre) by circular zone in Rome

Circular zone	Number of segments with traffic data	Length of segments (m)	Number of HTR segments	Length of HTR segments (m)	2001		2005 without policy scenario		2005 with optimistic policy scenario		2005 with pessimistic policy scenario
Circular zone	Number of segments with traffic data	Length of segments (m)	Number of HTR segments	Length of HTR segments (m)	NO₂	PM₁₀	NO₂	PM₁₀	NO₂	PM₁₀	NO₂	PM₁₀
Outside main ring	2004	1 323 052	543	463 192	21.3	6.8	16.2	5.5	16.2	5.5	16.2	5.5
Main ring	1147	541 428	459	214 046	22.9	7.6	17.4	6.1	17.4	6.1	17.4	6.1
Green strip	1584	472 273	710	202 360	26.3	9.7	20.2	7.6	20.2	7.6	20.2	7.6
Railway ring	1653	292 502	501	96 913	23.3	9.3	17.7	7.2	13.6	6.5	14.7	6.6
Limited traffic zone	201	35 771	15	2936	19.7	6.5	14.8	5.1	11.8	4.6	12.5	4.7
Total	6589	2 665 026	2228	979 447	22.9	7.8	17.4	6.2	17.0	6.1	17.1	6.1

We assumed that traffic composition only changed in the Railway ring and in the limited traffic zone.
HTR, high-traffic roads.