My new terrace sativa stealth grow + dust probs

I have 3 girls growing on my terrace, I used a screen to limit the height to about 35 cm, or about as high as the concrete on the terrace. Since it's the tallest building around nobody can see what's happening there. I have a police station about 50 meters from my place so I am a little worried, but I think it's safe as long as nobody knows. What do you think?

I also have some dust issues, as I grow in the city and it's very dusty here I have all kinds of crap on my plants, so I was wondering if I should wash them a little after harvest, or maybe even water cure.

I grow in soil, occasionally use some nutes.

Here is a pic of the "setup" - the plants are about 5 weeks old. The plant in the middle is grown from seed, the 2 plants in the sides are from clones. The middle plant started making crystals but the clones are still vegging I guess. I have direct sunlight from 1pm till the sun sets down, about 6 hours, it's not much but the plants are going well IMO.

as for dust, how quickly does it build up?
I would try a was off maybe a day or two before, and let it have time to dry again before harvesting.
Going into the dry box with extra moisture is just asking for mold problems...

Well, it depends, there was some construction work on the street the last few weeks, with lots of sand and dust, so I guess the plants became dusty in about 4-5 days. Now they stopped digging and also some rain dropped, so I hope from now on there won't be that much dust. The older fan leafs are pretty much dusty but the new growth looks clean, I just hope there is not too much dust in the buds by harvest time.