Aside form the front fender hole, I observed another reason for the increased and more coarse dust in the engine cavity.

I parked in a local Walter Mart here in Pampanga. Having some road work being done in the surroundings, the parking lot was dusty than normal.

When I was leaving and going on reverse, I noticed the radiator fan was strong enough to stir up the dust and since I was on reverse, suck it from the front and bring it into the engine cavity.

This will not happen of course during forward movement where we spend most of our driving.

Hope those of you wondering where all the dust is coming from finds this info more enlightening.