Inhalation exposure

The lungs have a huge surface designed for moving gases into the blood, so inhaled chemicals can reach the circulation within moments. Effects may be local, such as irritation or lung scarring, or systemic, such as dizziness or organ damage elsewhere.

What happens depends on the form of the material. Gases and vapors travel deep into the lungs, while larger particles tend to be caught in the nose and throat. Very fine dusts can reach the deepest airways. Water solubility also matters: highly soluble gases often irritate the upper airways first, while less soluble ones reach farther down.

Control of inhalation exposure follows the Hierarchy of controls. Ventilation and enclosure come first, with respirators as the last line of defense when controls are not enough. Respirator use must follow 29 CFR 1910.134, which requires a program, medical evaluation and a Respirator fit test where needed. Air contaminant limits are in 29 CFR 1910.1000 and related standards.

Smell is a poor safeguard. Some hazardous gases have no odor, and others deaden the sense of smell. The Odor threshold is not a safe limit, and monitoring or detectors may be needed.