Acid particles and the tracheobronchial region of the respiratory system. An irritation-signaling model for possible health effects
This paper explores some detailed mechanistic hypotheses for the possible action of acid particles on the tracheobronchial region of the human respiratory system. Because of the buffering capacity and volume of mucus produced per day it appears doubtful that ordinary ambient exposures to acid particles could markedly change the overall pH of tracheobronchial mucus considered as a whole. However, it is possible that individual acidic particles could contain enough acid to deliver localized irritant signals that could be the triggers for enhanced mucus secretion and cell division in sensitive portions of the bronchial tree, and thereby contribute to the processes involved in chronic bronchitis. Depending on the exact pH depression required for a signal to be perceived by the tracheobronchial epithelium, the acid content of the incoming particles per unit weight, and the effect of neutralization by ammonia in the upper respiratory tract, the minimum size of an acidic particle required to deliver a perceptible signal might range from about 0.4 to 0.7 microns for portions of the epithelium that are frequently swept by 4-micron mucus droplets. Since particle number per unit weight declines dramatically with increasing particle size, the most potent fraction of particles in terms of signals delivered per /sup +/g/m/sup 3/ is likely to be just above the minimum size that is needed to produce an effective signal. The model developed here makes predictions of the relative potency of particles of different size and acid delivery capacity that could be tested in both experimental animal systems and human epidemiological studies.
- Research Organization:
- Massachusetts Institute of Technology, Cambridge
- OSTI ID:
- 6367124
- Journal Information:
- J. Air Pollut. Control Assoc.; (United States), Vol. 37:9
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
BRONCHITIS
EPIDEMIOLOGY
PARTICULATES
HEALTH HAZARDS
BRONCHI
EPITHELIUM
INHALATION
MATHEMATICAL MODELS
PARTICLE SIZE
PH VALUE
TRACHEA
ANIMAL TISSUES
BODY
DISEASES
HAZARDS
INTAKE
PARTICLES
RESPIRATORY SYSTEM
RESPIRATORY SYSTEM DISEASES
SIZE
TISSUES
560300* - Chemicals Metabolism & Toxicology
550900 - Pathology