Expert: David L. Russell, PE - 4/17/2007

Question
QUESTION: hello, i am designing a building for a los angeles beach and i am trying to research ways of making it respond to the pollution of air and water in the area. i have read that the pH of the air changes with pollution and have been considering the development of litmus fabric as a sunshade material. any knowledge of already developed methods to measure pollution or materials that react to it, or make it visible would be very helpful. thank you!
ANSWER: You need to pay attention to your air handling system and the air quality. Most of the pollution will be acid gas, and an alkaline scrubber system and or activated carbon will clean up most of the air quite nicely.  You also may have some issues with the fine particulate in the air.  in that case you may also want a HEPA (High Efficency Particulate Air) filtration system to remove fine particles of salt and other foreign matter.
Pay attention to your metals coating systems and provide cathodic protection where necessary on exposed materials so that they won't corrode.  that may even mean the steel within the concrete in the foundation. Get a good Corrosion Engineer, a Member of NACE (http://www.nace.org) to review your materials selection.
Now about your question.  I don't know of any materials which will perform as you suggest you want them to. The effect of sunlight and the UV oxidation of the sun will very shortly cancel out any effects of colorings or coatings on the fabric.
Measuring the particulates, and the acid gasses in the air is relatively easy. Designing a system to respond to it and change color or provide some special properties has, as far as I know, never been done. I believe that you may be into the realm of nano technology for what you want and the systems have not been developed. You would be far better off with louveres which are keyed to the sun angle and the solar insulation -- which open and close when it gets dark or too bright.  That will also help balance your heat load and you may want to consider a plenum on the outside of the building to protect the louvres and use that space to condition or pre-condition the building air.


---------- FOLLOW-UP ----------

QUESTION: hi again, thanks very much for the quick and well rounded reply. Do you know about UV protective / materials?  Also, althought the pollution and smpg of Los angeles is very high and spreads, I would like to know whether you think it would still be slightly significant on the beach 15 miles from the city centre, where the daytime ocean breeze is opposing the air from the inland city. thanks very much for your help!

Answer
UV is a strong bleaching agent.  You need to contact some of the professional coatings manufacturers regarding UV resistant paints.  Ditto with the plastics mfgrs.  I believe that there is now a UV resistance specification by ASTM, but look at their web site and then ask questions.  The darker colors tend to fade more with UV because of the energy imparted.
If you are on the beach, presumably on the west side of LA, your largest concerns will be salt air corrosion (there is an ASTM Specification on that or contact the national society of corrosion engineers).  The problem will be with electrical equipment, especially aluminum and copper (yes, the electrical wiring in the building!). Salt air tends to corrode both, and given a choice I would prefer copper rather than aluminum wire because it has less potential to be reactive. (This is important if you want to avoid electrical fires). Condition and dehumidify the air in the building.  Oversize the A/C units by about 50%.  Most idiots who occupy the building are not thinking about the bad effects of moisture and salt on minor appliances like computers.  If you have a computer room you need a high performance A/C system, otherwise the life of the unit is very very short.
Your principal concerns are not involving ozone and smog, but salt and moisture.