I have a brand new 300,000 square foot warehouse building.  The
building is used only to store and distribute brand new automobile
tires.  There has never been any other use of the building.  My
problem is that when the heat turns on, we get a heavy haze (not
smoke) throughout the building.  The haze mainly resides in the upper
portion of the building (toward the ceiling).  We have had the heater
manufactures representatives and two HVAC contractors check the
heating units which they all say are working exactly has they should
be.

When the heat turns off, the haze goes away.  It only takes about one
hour for the haze to return after turning on the heat.  The type of
heaters used are two high volume and high efficient natural gas
heaters/blowers mounted from the ceiling 1 million BTU each.

The intake from the heaters processes about 90% indoor air and 10%
exterior fresh air and the emissions is to the interior of the
building, not the exterior.  There seems to be a very fine black dust
on the floor of the building.  Our only thought is that the tires are
coated with some type of material that is getting pulled in from the
intake of the two heaters, burned, and then emitted as a haze in the
warmer ceiling area.  We have called several other tire distributors
but nobody else seems to have this problem.

Can anyone shed light on what is happening and a solution?.  If you
have had a similar experience is there an exposure risk to worker
safety?  What are the risks (i.e. health based, fire, explosion, etc.)

---

Request for Question Clarification by pafalafa-ga on 09 Feb 2006 10:40 PST

John,

Wow, what a mystery.  I have some IAQ experience, but I really don't
have a clue about this one.

One question though...have you run the scenario past any of the tire
manufacturers themselves?

They're the ones with the familiarity as to what's in/on the tires,
and what sort of experiences have been the case at other storage
locations.

Let me know what sort of input you've had from them.

Good luck...

pafalafa-ga

---

Clarification of Question by john25-ga on 09 Feb 2006 18:01 PST

We have contacted the tire manufacturers but have not received any
helpful input yet.  We have also contacted approximately 5 other tire
warehouses and they do not have the same problem, but we beleive that
they do not have the same type of heaters.  Our heaters use an open
flame to heat the air as opposed to the more commonly used heat
exchanger.

I will suggest steps leading to the solution

1) Install dust monitor
 
    These instrument use an air pump and air filter to collect dist
     A bit like a small vaccuum cleaner.
2) Take collected sample to a lab and have content analysed
 

      Actually, a small vacuum cleaner would do, but there are industrial
      instruments built for this purpose. In some industries (mining) they are
      requred.

Here are few examples:

The DUSTTRAK is a portable, battery-operated laser photometer which
gives you a real-time digital readout with the added benefits of a
built-in data log
ttp://www.industrysearch.com.au/products/viewrecord.asp?id=8413

 Grimm 1100 series dust monitors utilize a built-in flow-controlled
pump to draw the sample in through the sampling head at a rate of 1.26
1pm as required for many industrial hygiene applications.
http://www.industrialsafetytalk.com/news/qua/qua105.html

http://www.laboratorytalk.com/news/qua/qua114.html



Health hazzard?
Yes. Particle size is an important factor:

Dusts greater than 10 microns in diameter tend to be trapped by the
cilia in the nose, while those particles in the 6 to 10 micron range
tend to travel only as far as the trachea. Dust and particulates, 3 to
5 microns. travel as far as the bronchia.

http://www.dustmonitor.com/articles/provides_data.htm
http://www.ciwmb.ca.gov/LEACentral/Cleanup/Projects/LaMontana/HealthSafety.doc.


Some instruments measure the opacity (visual manifestation of haze)
The AethalometerTM measures ambient pollutant species of suspended
carbonaceous particles, which are a ubiquitous component of traffic
and industrial combustion emissions. (See Appendix B.)

Continuous Particulate Monitors (CPM) are variants of opacity meters
used for stack sampling of PM emissions and moniyors
http://www.rand.org/pubs/monograph_reports/MR974/MR974.AppA.html


You may want to describe where you are. Chances are that local EPA office
would know how to measure the aerosol.

About the Field Research and Consultation Group (FRCG)
Since 1956, the Field Research and Consultation Group has served the
occupational safety and health needs of the state of Washington. Our
services are provided without charge to businesses and labor groups in
the state. Part of our funding comes from employers and workers in
Washington State through their contributions to the Medical Aid and
Accident Funds.
http://depts.washington.edu/frcg/prj_concrete.html





Search terms:
 dust analysis
 dust monitor
 aerosols and particulates
  Air Sampler 
Hedgie

You are burning NG at the top of the building to heat it ?

That is rather inefficient.

Probably, yes, you are raising particles of rubber, incinerating them
and creating clouds.

If the system was expensive, and you do not want expend much more
capital, then I suggest that you install some ducting that draws hot
air from the top of the building down to the bottom level (recycle
heat as it wants to go), but it would be sensible to filter the air.

On the plus side you have a visible sign of a problem, on the down
side, you have selected incompetent heating contractors.

I'm not sure about the filters for micro particles of rubber,
diffusing (or solidifying) it through water is unlikely ... perhaps an
expert will pop up

However, I know for sure that your heating system is upside down, and
you need to clear out the rubber gunge, before somebody twigs what is
happening.

At a guess, ducting extracted air and detritus from the ceiling, could
be run round the base of the warehouse for very little cost, filtering
the crud is more of a problem, but if you are not that worried about
heating bills, then you could simply pump it through cold wet sand

Sunshine, you got a problem, a rubber haze could ignite

Any experts on filters ?
.... Cmon Captain F - this is your forte

My solution would be cleaning the particles by ion bombardment. Just
install a tube with a fan in the ceiling and connect with a high
voltage power source. That would circulate the air and so you would
get no extra costs of re-heating it.
This method also filters the smallest particles unlike conventional
filters. The power consumption I would estimate at around 1-2 kW.

--Andres

I'm thinking it might be a humidity issue...  any idea what the
relative humidity is?  For the given humidity (whatever it is), is the
temperature somewhere around the dewpoint?

What are the temperatures of inside and outside air?  Any open water
inside the building?

One of the products of combustion for any hydrocarbon is water
vapor...  This might be what's accumulating at the top of your
building... depending on the temperature and RH, it might show up as
fog.

CH4 + 2(O2) --> 2(H2O) + CO2  (neglecting nitrogen)

So you're gonna get carbon dioxide and water vapor...  Unless the
combustion is fuel rich, you shouldn't get any unburned hydrocarbons
in your products.  Everything should be safe for the workers.

To be on the safe side, is there any way to increase that 10% of
outside air?  Maybe 80/20 or 75/25?

On very cold days, does the fog still appear?  I was thinking if it
was indeed water vapor, it might condense on the ceiling (if
un-insulated) on colder days...

you can find more information at www.drumair.com

As for the very fine black dust, if you utilize forklifts, I would say
its from the forklift tires. On the other matters in california
CALOSHA offers a free consultation service. I would check with your
states OSHA.

The haze observed by you is due to soot from incomplete
combustion.Either the burners are faulty or the setting is incorrect.
 The soot remains suspended in the hot air , and when this air cools
down the soot also settles down to the floor.
 Incomplete combustion can be caused both by lean mixture or rich mixture.
 The tires do not release any significant gas.
 The soot and air mixture can be highly explosive, and is dangerous
given the nature of stores.
 The soot is also hazardous to health.
 There is no necessity for filters once the combustion is corrected.

I investigated a similar situation in the UK.  This was in an unheated
paper warehouse.  A layer of black particles was being deposited on
every surface.  The warehouse has quite a heavy fork lift usage, and
concluded that this was FLT tyre dust.

You may be experiencing a similar thing, although the heating system
may well be the true cause.  I would suggest spreading the dust on
paper to see if the particles mark the paper.  If it does, you should
suspect the heating system not burning stochiometrically.  If not, it
is most likely to be FLT tyre dust.  I cannot envisage a mechanism for
the stock being the source.


Regards
Jon

My hunch is that there is rubber dust coming from the tires.

It should be quite easy to check with a small hand held vacuum cleaner.

If you can get a fair amount of black rubber dust in the bag, then you
know the cause.

It could be FLTs - but given the stock in this case, I would go for the obvious.

Piles of rubber tires will have manufacturing debris, and sufficient
movement to produce particles from friction - perhaps enough to
simulate 1000 FLTs.