ASHRAE Journal - February 2013 - 76

iaq applications
steps to determine what these health impacts would do to our
lives in terms of money.14
The concept that allows us to compare the health impacts
of different indoor hazards is known as disability adjusted
life years (DALYs). One DALY is the equivalent of one year
of healthy life. The DALY loss from given contaminates
was estimated by Logue et al.,13 using population exposure
and harm data. We can use this approach to find out how
important the stuff we breathe actually is for chronic health
impacts.
Very Important. From the point of health damage to the
population there is one contaminant that stands above all others—particulate matter, specifically PM2.5.15 Logue found that
most of the DALY damage of indoor air was from exposure to
particles.16 Particles come from both indoor17 and outdoor18
sources.

Important. There are two volatile organic compounds
(VOCs) that show up as important: formaldehyde19 and acrolein.20 Acrolein is principally produced by combustion of
carbon-based fuels. If products of combustion were not emitted into the indoor environment, acrolein would not likely be
a significant problem.
There is one other compound that might be included in this
category: water. Water21 itself is not the health hazard, but the
microbiologicals22 that poor water or humidity management
can allow to grow. This has not been studied much in the U.S.
as far as its DALY impact, but the Europeans23 have found it
to be important.24
Sometimes Very Important. There were three contaminants
that had a lesser, but noticeable, impact on the health of the
population as a whole: secondhand smoke (SHS), ozone and
Radon. For each of these, there is a significant portion of the

14You’ll be happy to know that a year of your life is worth something like $100,000 (to within a factor of two), depending on who you are and if you were
happy with the Presidential elections. This number actually can be useful when trying to compare IAQ impacts with energy and productivity impacts, but I am not
about to do that here. 15Particle mass below 2.5 microns in size. 16The “know not enough” will tell us—quite rightly—that not all particles are equal and that
some particles are more equal than others. This admonition is a reason to continue relevant research, but not to back off acting on the information we have now.
17Important indoor sources include cooking, combustion and indoor chemistry.18Important outdoor sources are from combustion processes including cars and power
plants. 19Formaldehyde is principally emitted (and stored in) materials, although there is some produced by indoor chemistry. 20Acrolein, which is a simple aldehyde,
is an extremely irritating gas that was used in the chemical warfare campaigns in world war two. 21Indoor humidity control is an important part of HVAC, which
is often ignored and therein lies a whole different story—and a lot of lawsuits. 22Think mold, fungus and their spores. 23Fernandes, E., et al. EnVIE Co-ordination
Action on Indoor Air Quality and Health Effects, Project no. SSPE-CT-2004-502671. 24OK, The U.S. is not Europe and it may not be as much of a problem, but it
might be. It could be more of a problem, especially in the southeast of the country. So I am provisionally putting it in this category.

ASHRAE Journal

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February 2013

ASHRAE Journal - February 2013

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