FACTSHEET
Controlling dust during demolition
Demolishing a city’s central business district has provided
unique opportunities for health authorities and safety
enforcement agencies to investigate what impact a dusty
environment potentially has for workers. Inspectors also
found that despite the hazards in this environment, workers
were not taking all practicable steps to keep themselves
safe.
■ Dust monitoring project
The Ministry of Business, Innovation and Employment –
Labour (MBIE - Labour) conducted a dust monitoring project
in the Christchurch central business district (CBD) over
the summer of 2011-2012. Health and Safety Inspectors
observed:
•P2 or P3 respirators should be provided to employees
along with training in their use. These particulate
masks or filter masks are widely available, and offer
more protection than the basic P1 masks, as their filter
efficiency is more effective.
•Employees who have to wear respirators should be cleanshaven, so that the masks fit properly around the nose
and mouth. These respirators do not fit properly if the
workers have facial hair. Alternatives for workers with
facial hair include using full face-piece respirators (more
expensive than particulate masks) or transferring them
to work areas where there is no dust.
•poor dust suppression measures
•machine operators working with their cab doors open
•workers not using appropriate respiratory protection
(personal protective equipment, or PPE)
■ Findings
The dust project and its findings have national implications,
as dust is a problem for construction and demolition sites all
around New Zealand.
The findings identified that brick and masonry crushing
generated the highest levels of dust. Effective dust
suppression measures varied considerably from site to site,
along with the numbers of workers using suitable PPE (dust
masks).
However, thanks to the use of air filters inside mobile
machine cabs, machine operators working with the doors
closed were not exposed to excessive levels of dust.
Figure 1: Dust is generated by the mechanical demolition process.
■ Recommendations
MBIE - Labour recommends the following actions:
•More effective and targeted dust suppression. The use
of water sprays and even snow-making machines are
useful for dust suppression. Water spray hoses are less
effective than water spray machines, particularly in high
wind conditions.
•Machine cab doors and windows should be closed at all
times when demolition is in progress.
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•Air filters in machine cabs should be serviced or changed
according to the manufacturers’ recommendations.
A written schedule should be in place and available for
inspection.
•A non-smoking policy should be implemented to prohibit
smoking while operating machinery or working on site.
The Ministry of Business, Innovation and Employment
– Labour takes no responsibility for the results of any
actions taken on the basis of this information, or for any
errors or omissions.
Figure 2: A water spray unit is used to wet down truckloads of
demolition debris.
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FACTSHEET
■ Additional requirements if using respirators
■ Follow-up action
Respirators only minimise the user’s exposure to dust - it
does not prevent the user from exposure and potential
harm. Employers are required to take all practicable steps
to ensure that the work environment is safe, and the use
of respirators over other methods that may eliminate or
isolate atmospheric contaminants from employees is not
recommended.
Since the conclusion of the dust control project, there
has been a significant improvement in dust control
methods within the Christchurch CBD. However, some work
sites have not implemented any of the Labour Group’s
recommendations.
However, if the employer has determined that respirators
have to be used, either on its own or as part of a combination
of other hazard controls, other duties are required to ensure
that respirators are used most effectively. These include:
•ensuring that respirators are the most appropriate for
the task, environment and contaminant(s)
•providing training to employees so that they can fit the
respirators correctly, how to clean, store and care for
them, and when to change disposable parts (such as
filters) so that the respirator continues to function as
required
Health and Safety Inspectors assess dust control compliance
on demolition sites nationwide, and will take enforcement
action where repeated non-compliance is observed.
■ Further information
Best Practice Guidelines for Demolition in New Zealand
(2011). New Zealand Demolition and Asbestos Association.
The guideline is available to view at http://www.osh.govt.
nz/order/catalogue/demolition.shtml and is available for
purchase at www.demolition-asbestos.co.nz.
•ensuring that employees use the respirators
appropriately and when required
•monitoring the employees’ exposure to the hazard, to
ensure that it is not excessive or beyond the means of
hazard controls
•taking all practicable steps to obtain employee consent to
monitor their health in relation to the hazard.
If employees are required to use respirators, they are legally
required to wear or use them.
The Department of Labour takes no responsibility
for the results of any actions taken on the basis of
this information, or for any errors or omissions.
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