Respiratory Diseases and the Fire Service - IAFF

18 Chapter 1-2 • Occupational Risks of Chest Disease in Fire Fighters
helium, nitrogen and nitrogen oxide. Examples of chemical asphyxiants are
carbon monoxide, cyanide, hydrogen sulfide and arsine gas. 3 The symptoms
and signs of hypoxemia and anoxia (low oxygen in the blood) can include
lightheadedness, shortness of breath, chest pain, coma or death.
The effects of exposure to irritants such as hydrogen chloride, sulfur
dioxide, phosgene, acrolein, ammonia and particulates are dependent on
the size of the particle and how readily the chemical dissolves in water. These
properties determine where in the respiratory tract the chemical or particle
is deposited and absorbed. Hydrogen chloride is very soluble therefore injury
occurs in the upper airway as opposed to phosgene which effects mainly in the
lower respiratory tract (the lungs). 3 At high dose exposure, particle size and
solubility are less predictive of the site of injury and there may be a pan-airway
inflammatory response involving upper and lower airways and even alveoli.
The irritants cause injury to the epithelial lining of the respiratory tract and
inflammation. As discussed above this causes a variety of symptoms such
as cough, shortness of breath, chest pain and increased mucous production.
A number of studies of smoke inhalation in fire fighters have demonstrated
increased symptoms, transient hypoxemia, hyperreactive (spasmodic or
twitchy) airways and changes in pulmonary function test measurements.
However, other studies have showed little effect and this is thought to be
due to the increased use of respiratory protective equipment in more recent
times. 4 A brief description of the studies of pulmonary function in fire fighters
is found below.
Chronic Effects on Pulmonary Function, Respiratory Illnesses
and Mortality
Studies of the long term effects of repeated exposure to smoke have not been
conclusive. Many of the studies summarized below do not indicate that fire
fighters have a significant decline in lung function over time. The findings of
these studies may be influenced by factors such as fire fighters with respiratory
disease transferring to non-firefighting duties or retiring or an underestimate
of the effect because of the healthy worker effect. Improvement in respiratory
protective equipment and its use is also likely preventing the development of
chronic lung disease. 4
SUMMARY OF STUDIES OF PULMONARY
FUNCTION IN FIRE FIGHTERS
The Forced Vital Capacity (FVC) is the total amount a person can breathe in
or out with a single breath. The Forced Expiratory Volume in the first second
of exhalation (FEV1) and Force Expiratory Flow measured in the mid-portion
of exhalation (FEF25-75) can be used as measures of airway resistance. More
can be found about these and other pulmonary function tests in the separate
chapter on pulmonary function testing in this book. What follows here is a brief
description of the relevant literature on pulmonary functions in fire fighters.
Peters et al 1974: Measured pulmonary function at the start of the study
and then one year later in 1,430 Boston fire fighters. The FVC and FEV1 both
decreased more than expected over a one year time period. The rate of loss for