412 Energy Project Financing: Resources and Strategies for Success
nella may also be present in potable water systems and aspiration of
potable water is also thought to be a potential source of infection with
Legionella. Some fungi, from sources within a building, can also infect
individuals who are immune compromised.
Infectious communicable bioaerosols generated by one person
may cause disease in others. These bioaerosols contain bacteria or virus
within small droplet nuclei produced from the drying of larger liquid
droplets, often expelled during coughing or sneezing. Examples of re-
spiratory diseases transmitted, at least in part, by bioaerosols include
tuberculosis, influenza, measles, and some types of common colds. Sev-
eral studies, as reviewed in Fisk and Rosenfeld (1997), have indicated
that building characteristics may significantly influence the incidence of
respiratory disease among building occupants.
Fibers in indoor air include those of asbestos, and man-made
mineral fibers such as fiberglass, and glass wool. The primary indoor
sources are building materials, especially insulation products. Exposures
to asbestos in industrial settings have been shown to cause lung cancer
and other lung disease. Fiberglass and glass wool fibers are a source
of skin irritation. The link between fiberglass and glass wool fibers and
lung cancer remains uncertain.
Environmental tobacco smoke (ETS) is the diluted mixture of pol-
lutants caused by smoking of tobacco and emitted into the indoor air by
a smoker (as opposed to the mainstream smoke inhaled by a smoker).
Constituents of ETS include submicron-size particles composed of a
large number of chemicals, plus a large number of gaseous pollutants.
ETS is a source of odor and irritation complaints. Panels of experts
have reviewed the scientific evidence pertaining to the health effects
of ETS and concluded that ETS is causally associated with lung cancer
and heart disease in adults and asthma induction, asthma exacerbation,
acute lower respiratory tract infections, and middle ear infection in
children (EPA 1992, California EPA 1997).
4.5 CONTROLLING INDOOR POLLUTANT CONCENTRATIONS
The indoor concentration of a particular air pollutant depends on
the outdoor concentration, the indoor pollutant generation rate, and
on the total rate of pollutant removal by ventilation, air cleaning, and
other removal processes. A simple mass balance equation can be used
to illustrate the relationship among these variables at steady state in a
space with well-mixed air: