  The orbital evolution of asteroidal, trans-Neptunian, and cometary dust
particles under the gravitational influence of planets, the Poynting-Robertson
drag, radiation pressure, and solar wind drag was integrated. Results of our
runs were compared with the spacecraft observations of the number density of
dust particles and with the WHAM observations of velocities of zodiacal
particles. This comparison shows that the fraction of cometary dust particles
of the overall dust population inside Saturn's orbit is significant and can be
dominant. The probability of a collision of an asteroidal or cometary dust
particle with the Earth during its dynamical lifetime is maximum at diameter
about 100 micron.
