Vapour section head head

VGDF (Vapours, Gases, Dusts, Fumes)

The term vapours, gases, dusts & fumes (VGDF) describes a group of inhalation hazards that are known to increase the risks of certain  respiratory diseases, including chronic obstructive pulmonary disease (COPD) and idiopathic pulmonary fibrosis (IPF). In other words, VGDF represents a mixture of harmful airborne agents present in the workplace, such as mineral dusts and toxic gases/fumes. VGDF does not have a single occupational exposure limit or other maximum exposure, and will not represent a uniform exposure. VGDF exposure represents an overall exposure to inhaled respiratory hazards. VGDF may be identified in self-reported questionnaires, job exposure matrices, or other qualitative or semi-quantitative measures of inhalational hazards.

lungsLungs don’t process each individual exposure separately, but are processing the overall cumulative exposure. When exposed to aVGDF mixture, our lungs process different respiratory irritants simultaneously and the lungs experience toxic effects of the agents in an additive manner (sometimes multiplicative). In cases where different agents contained in the VGDF have the same target organ, it’s appropriate to apply a “mixture” calculation to the occupation exposure monitoring.

The mixture calculation is the sum of every measured concentration (C) divided by every chemical’s occupational exposure limit (OEL). If the mixture calculation exceeds 1, then the threshold limit of the mixture is exceeded:


This equation recognizes that the individual effects are additive. This calculation would be an underestimate of the synergistic effects of chemicals within the mixture. Therefore, this calculation can’t be applied when the effects are multiplicative (“potentiation”).

*Potentiation = one chemical increases the potency, or adverse effects, of another chemical

*Synergistic = two chemicals combined to have health effects that are greater than additive

The mixture equation is also difficult to apply to: 1) carcinogens and; 2) complex mixtures, particularly when these mixtures only have 1 or perhaps 2 chemicals monitored, such as complex solvent mixtures or diesel exhaust.


Chronic Obstructive Pulmonary Disease (COPD): Occurrence and Associations with Occupational Exposures and Smoking

Occupational Lung Disease: Overview, Risk Assessment, Diagnosis

OCC-TOBER 2020: Leading into November: Lung Month (Work-Related Lung Disease)

Position Statement: The Occupational Burden of Nonmalignant Respiratory Diseases: An Official American Thoracic Society (ATS) and European Respiratory Society (ERS) Statement