2. Literature review
Excessive dust emissions can cause both health and industrial
problems, e.g. health hazards, risk of dust explosions and fire, dam-
age to equipment, impaired visibility, unpleasant odours and even
problems in community relations. Excessive or long-term exposure
to harmful respirable dusts may result in a respiratory disease called
pneumoconiosis. This disease is caused by the buildup of mineral or
metallic dust particles in the lungs and the tissue reaction to their
presence. Silicosis is one of the most common pneumoconiosis in
Hong Kong. According to the Annual report by PCFB (2011), there
are 951 confirmed new cases of silicosis from 2000 to 2009, and
89% of cases have employment records in the construction/quarry
industry.
2.1. Existing guidelines and limits for silica exposure
Silicosis, which is caused by the dust of quartz and other silicates,
is irreversible, often progressive (even after exposure has ceased),
and potentially fatal. In order to control the health hazard brought
by dust, government and statutory bodies in Hong Kong and else-
where have issued a number of regulations. Besides the regulations,
a number of professional associations, e.g. the American Conference
of Governmental Industrial Hygienists (ACGIH), National Institute
of Occupational Safety and Health (NIOSH), have also adopted a
number of standards, commonly known as Threshold Limit Values
(TLVs), to evaluate the severity of health hazard in a workplace.
These values are used as guides in the evaluation of health hazards.
TLVs are time-weighted concentrations to which nearly all workers
may be exposed 8 h per day over extended periods of time without
adverse effects. Table 1 lists the current US, UK and Hong Kong
guidelines and limits for occupational exposure to crystalline silica.
2. Literature review
Excessive dust emissions can cause both health and industrial
problems, e.g. health hazards, risk of dust explosions and fire, dam-
age to equipment, impaired visibility, unpleasant odours and even
problems in community relations. Excessive or long-term exposure
to harmful respirable dusts may result in a respiratory disease called
pneumoconiosis. This disease is caused by the buildup of mineral or
metallic dust particles in the lungs and the tissue reaction to their
presence. Silicosis is one of the most common pneumoconiosis in
Hong Kong. According to the Annual report by PCFB (2011), there
are 951 confirmed new cases of silicosis from 2000 to 2009, and
89% of cases have employment records in the construction/quarry
industry.
2.1. Existing guidelines and limits for silica exposure
Silicosis, which is caused by the dust of quartz and other silicates,
is irreversible, often progressive (even after exposure has ceased),
and potentially fatal. In order to control the health hazard brought
by dust, government and statutory bodies in Hong Kong and else-
where have issued a number of regulations. Besides the regulations,
a number of professional associations, e.g. the American Conference
of Governmental Industrial Hygienists (ACGIH), National Institute
of Occupational Safety and Health (NIOSH), have also adopted a
number of standards, commonly known as Threshold Limit Values
(TLVs), to evaluate the severity of health hazard in a workplace.
These values are used as guides in the evaluation of health hazards.
TLVs are time-weighted concentrations to which nearly all workers
may be exposed 8 h per day over extended periods of time without
adverse effects. Table 1 lists the current US, UK and Hong Kong
guidelines and limits for occupational exposure to crystalline silica.
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