Figs. 4–5.

(a) Average size distributions measured during 60 h of testing in truck traffic on a New York State freeway. Results are shown with and without a thermal denuder that removes semi-volatile particles. (b) Normalized particle size distributions measured during 60 h of testing in truck traffic on a New York State freeway. They have been normalized to give a constant number concentration in the accumulation mode so that the relative size of the nucleation and accumulation mode can be seen. Results are shown for an ambient temperature range from 9.6 to 23.2 C.

Adapted from Kittelson, Watts, Johnson, et al. (2004).