Bioaerosols - Aerosols: Measurement, Dosimetry, and Health Effects - page 300

2%-3% in New Zealand, 91 2%-6% in the United Kingdom, 92 although one study estimated 28%, 93
and 17% and 29% in Finland for men and women, respectively. 94
12.2.2.2 Rhinitis
Rhinitis is caused by allergic or nonallergic inlammation in the mucosa of the upper respiratory
tract. Typical symptoms include sneezing, rhinorrhea, and nasal congestion (runny or stuffy nose)
often accompanied by tears, itchy eyes, and red and swollen eyelids (conjunctivitis). One of the con-
sequences of the nasal obstruction associated with rhinitis is greater oral breathing, which bypasses
some of the body's defenses and may lead to greater susceptibility to airborne infectious agents
(Section 12.5.1). 95
As with asthma, rhinitis has increased in the last few decades, and approximately half of all rhi-
nitis appears to be allergic. 96 Episodic symptoms are the hallmark of “hay fever” or allergic rhinitis
caused by pollen or fungi. The list of pollen types that may cause hay fever is long and includes rag-
weed; Russian thistle; English plantain; timothy, rye, and other grasses; and birch, maple, oak, and
willow trees. 77 The outdoor environment is the primary source of pollen exposure, although indoor
occupational allergy to lower pollen also has been documented. 97 While rhinitis is associated with
asthma they are separate conditions. 98
Nonallergic rhinitis in the general population is common and is most likely caused by air pollut-
ants and other chemical exposures. Bioaerosols also may play a role, for example, endotoxins and
fungi, but most studies linking bioaerosol exposure and nonallergic rhinitis have been conducted
in the occupational environment (Section 12.3.3). Occupational, nonallergic rhinitis is sometimes
referred to as “mucous membrane irritation” and is characterized by dry cough and irritation of the
eyes, nose, and throat. It is among the most commonly observed occupational conditions associated
with occupations with high bioaerosol exposure, for example, farming.
12.2.2.3 Organic Dust Toxic Syndrome
ODTS is a nonallergic, acute, febrile illness, characterized by fever, shivering, dry cough, chest
tightness, dyspnea, headache, muscle and joint pains, fatigue, nausea, and general malaise. 86 The
symptoms resemble those of inluenza but usually disappear in 1 day. ODTS is also known as “toxic
alveolitis” or “inhalation fever.” Historically, this syndrome of symptoms was named after the par-
ticular environment in which it was observed, for example, “mill,” “grain,” or “humidiier” fever or
“silo unloaders syndrome.” ODTS is based on an acute, intense, airway inlammation characterized
by neutrophilia, typically requiring 4-8 h to manifest fully following exposure. No prior sensitiza-
tion is required and, with suficiently high exposures, all exposed persons may develop the disease.
Repeated exposures can induce adaptation or tolerance, and ODTS may not reappear until there is
an unusually high re-exposure or after a period of absence, for example, a holiday.
ODTS is relatively common where workers are highly exposed to bioaerosols, but may also
occur in the home or ofice environment where heavily microbially contaminated humidiiers or
air-conditioning systems are in use. The disease is particularly common among farmers and work-
ers in the textile iber processing industry. Microorganisms and bacterial endotoxin are believed to
be the main causes. 86
12.2.2.4 Hypersensitivity Pneumonitis
HP is used synonymously with extrinsic allergic alveolitis, “farmer's lung,” or “pigeon breeder's
lung.” HP is a generic term used to describe a restrictive, obstructive or mixed restrictive/obstruc-
tive, pulmonary condition with delayed, febrile, systemic symptoms, manifested by an inlux of
inlammatory cells to the lung parenchyma and the formation of granulomas there. Prior sensitiza-
tion is required, which is believed to involve Type-III or -IV hypersensitivity, but the immunological
mechanisms are still only partly understood. 99
Typical symptoms of acute HP include systemic ones, such as fever and chills, as well as chest
tightness, dyspnea, and cough, and closely resemble those of ODTS. 100 HP symptoms develop 4-8 h