[Greenbuilding] Indoor Air Quality

[JAY WALSH]

My recent post “No place for wood burning open fireplaces in Green
Building” had more to do with the adverse health effects of indoor air
pollution (though I have an equal concern for outdoor pollution).  My post was
in response to the use of open fireplaces and the suggestion to abandon the
use of a range hood vented to the outside for an internal circulating filtered
type range hood. 

I see indoor air pollution and energy conservation in three ways: 

1. Remove Dangerous Gasses: Carbon Monoxide from heating (including wood
burning sources) and cooking appliances, and Radon which attaches to dust in
the home and particulates from unvented cooking appliances and is then inhaled
into the lungs.
2. Energy Conservation: Insulate well, build tight, but ventilate right!
3. Humidity Control: Control humidity levels to combat the development of
toxic mold within the home.

As one of my primary jobs is to test homes for the items above, I am very
concerned by carbon monoxide and the levels I find in the typical home. While
heating systems can be deadly sources of CO I have a growing concern over the
recent health studies on the health effects of long term low level CO
exposure.  A typical gas cooking stove produces a constant 15-35 parts per
million (ppm) of CO and at the start up of the oven as much as 400 ppm. 
For these reasons I am suggesting that you should always choose to ventilate
the gasses and particulates from cooking appliances to the outside. P.S. Never
ventilate the range hood into your Heat recovery ventilator (HRV).

Effects on health of prolonged exposure to low concentrations of carbon
monoxide 
C L Townsend and R L Maynard 
Department of Health, London, UK 
Several studies have attempted to determine levels of carbon monoxide in
people’s homes.9,10 Schaplowsky et al measured blood COHb levels in about
3000 children in the USA, as well as CO concentrations in 1820 randomly
selected homes.9 They found that 22.5% of children (n = 517) had blood COHb
levels above 3%. Highest levels were around 8%. Of the homes tested for CO
concentrations, about 17% (n = 306) had levels above 10 ppm. These raised
levels of CO were primarily caused by defective or improperly vented fuel
burning appliances. However, passive smoking was not taken into account, and
it is known that this can play an important part in raising indoor
concentrations of CO. Nevertheless, this study suggests that a large
proportion of the population may be unknowingly exposed to carbon monoxide
levels above those considered safe….
As it seems likely that many people are exposed to CO in their homes, it is
important to determine what effects this may have on their health. For normal,
healthy individuals, the effects may be small or non-existent. However certain
individuals, such as children, the elderly, pregnant women, and people with
chronic diseases involving impaired blood supply to the heart and brain may be
more susceptible to increased levels of CO….

Long Term Effects of Carbon Monoxide Poisoning
SilentShadow.org
Some of the long term effects of low level exposure are still unknown, so it
can often be difficult to ascertain what sort of effect this hazardous gas may
have upon your life. 
Although the majority of people that suffer long-term effects from carbon
monoxide poisoning do recover in time, there are those that will suffer
permanent damage. 

Environmed Research Inc., Sechelt, British Columbia, Canada 
Indoor Air Quality .Carbon monoxide (CO)
Carbon monoxide gas is produced when fossil fuel burns incompletely because of
insufficient oxygen. During incomplete combustion, the carbon and hydrogen
combine to form carbon dioxide, water, heat, and deadly carbon monoxide. In
properly installed and maintained appliances gas burns clean and produces only
small amounts of carbon monoxide. Anything which disrupts the burning process
or results in a shortage of oxygen can increase carbon monoxide production.
Wood, coal, and charcoal fires always produce carbon monoxide, as do gasoline
engines.

I apologize to the long posting here but the issue of indoor air quality is of
great concern to me as we are building tighter homes.

Sincerely, Jay Walsh, Center for Ecological Technology