lec 4 Occupational Respiratory diseases

Occupational lung diseases
are a broad group of pulmonary disorders that develop from inhalation of specific particles.
Historically, they have been a major cause of morbidity and mortality before workplace safety guidelines were rigorously established and enforced.
Although each disease has a slightly unique presentation, they all lead to progressive deterioration in lung function that can cause severe respiratory compromise if appropriate measures are not undertaken.


Occupational asthma
airflow limitation and airway hyper-responsiveness caused by specific agents inhaled in the workplace.
It does not include activation of pre-existing asthma or airway hyper-responsiveness induced by non-toxic irritants or physical stimuli such as cold air.
Two types of occupational asthma are recognised:
Immunological asthma appears after a latent period of occupational exposure;
Non-immunological occupational asthma develops without a period of latency and is associated with exposure to high concentrations of irritants also called (reactive airways disease).

Byssinosis
Hypersensitive airways and acute reduction in FEV1 (asthma-like breathing) in susceptible individuals when they are exposed to dusts of cotton or flax.
Also called Monday fever or cotton workers lung.
Acute dyspnoea with cough and chest tightness on the first day of the working week, then symptoms improve on subsequent working days, despite continued exposure to the sensitizing agent.
As the disease progresses the symptoms recur on subsequent days of the week, and eventually even occur at weekends and during holidays.
If the workers who develop byssinosis are not removed from further exposure, they go on to develop long term respiratory impairment and subsequently have an excess risk of mortality from respiratory disease.