# B How high does a wall need to be to block smoke?

1. Jun 30, 2017

### CassieFordham

A smoker just moved into the mobile home next to the one I live in, and insists on smoking in his yard. I want to build a wall between us to block the smoke. I don't know how to calculate how high the wall needs to be, to keep the smoke from blowing into my yard. Can anyone help me to figure this out?

2. Jun 30, 2017

### Staff: Mentor

Does your mobile home park have CC&Rs? And maybe your city has laws for how close smokers can be to occupied dwellings. What country/state/province do you live in?

http://www.nolo.com/legal-encyclopedia/what-are-convenants-conditions-restrictions-ccrs-hoas.html

Last edited: Jun 30, 2017
3. Jun 30, 2017

### Drakkith

Staff Emeritus
Offhand I'd guess it needs to be at least 6-8 feet, but I'm not sure how effective a fence will be since they aren't usually airtight.

4. Jun 30, 2017

### Staff: Mentor

And the wind direction is a bigger factor anyway. Can you just ask them politely to go downwind to smoke?

5. Jun 30, 2017

### CassieFordham

Thank you all for your replies, but my question is a physics question. I'm trying to build a wall, not change the behavior of my neighbor.

I want to know how to know the formula to figure out the behavior of the smoke: e.g. under what conditions wound the smoke rise and what conditions would it fall, and what conditions are needed to ensure that itdoesn't to rise above the wall then fall into my yard where I would breath it.

6. Jun 30, 2017

### davenn

there's just too many variables .... height isn't going to make a lot of difference when as @berkeman said it is windy
the wind will just blow the smoke around the sides and over the top of the wall. And even if it isn't windy, and
you had a 20, 50, 100 ft high wall. It's still going to drift around the sides of the wall

So do you want to encase you home or his home in a plastic bubble ?
that is the guaranteed way to stop the smoke, every other way will fail to some extent

Dave

7. Jun 30, 2017

### A.T.

It's an engineering question. It's solved with engineering tools, like CFD simulations. Or by trial and error.

8. Jun 30, 2017

### Drakkith

Staff Emeritus
I'm not sure this is possible. The behavior of air patterns is enormously complex and depends on a huge number of variables, such as absolute temperature, temperature variations, the exact location and properties of surrounding structures and vegetation, amount of sunlight, exact location of your neighbor, etc.

9. Jun 30, 2017

### 256bits

There is no formula that fits all scenarios.

You could try concentration dispersion, such as how will it take for a smell ( perfume for ex ) to cross a distance, just by the movement of molecules themselves. Around a barrier adds a complication.

Wind drift, gravity fed movement, convection, smokestack, atmospheric conditions, etc all in puts and/or choices used to model movement of particles and aerosols in air for say pollutants, chemical agents, fire, etc.

Look up air dispersion modeling to see what's out there. Most programs would be for larger areas - 1000's of feet to miles and miles from the source. You might get lucky to find something for smaller areas, very low concentrations, and brief time periods. If you are more lucky, you might be able to find some expose on equations, applicability, and the importance of factors in the modelling.

wiki has a little bit
https://en.wikipedia.org/wiki/Atmospheric_dispersion_modeling

Chugg away/ A small scale model for barbeques and cigarette smoke would be an interesting application for urban dwellers, and other interested parties.