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Silent Killers

Published: 03rd Mar 2014 in OSA Magazine

Dr Sammy Wan explores behavioural change in the use of respiratory protective equipment on Hong Kong construction sites.
When people think of hazards on construction sites, images of collapsed scaffolding, overturned machinery or electrocution often spring to mind.

In fact, it is the silent killers such as dust inhalation, asbestos, heat stroke/exhaustion, lung function failure, strain and heart failure that are more likely to kill people in the construction industry than quick action accidents.

In Hong Kong, there were 280 confirmed cases of occupational disease in 2012. Of these, 44 cases of silicosis were reported in the construction industry. Each of the cases involved workers who had been exposed to silica dust for many years. In the same year there were 14 cases of gas poisoning. Interestingly enough, there were also 12 confirmed cases of compressed air illness, some of which may have been as a result of the tunnel works taking place on various railway projects in Hong Kong. It is clear from the statistics in Table 1 that more than 35 percent of occupational diseases could have been prevented if respiratory protective equipment (RPE) had been properly used.

In Hong Kong, the awareness of wearing RPE is low when compared with other forms personal protective equipment (PPE) such as safety helmets and shoes (Tam and Fung, 2008). Some workers may find that wearing RPE is not comfortable when carrying out work in hot, humid, poorly ventilated, and confined areas of construction sites such as machine rooms, water tanks, shafts and tunnels. Often workers are not aware of the detrimental effects that not wearing the correct RPE can have to their health. In many cases, signs of disease many not appear straight away, but instead may develop later - weeks or even years after exposure.

Capelo and Dias (2009) indicated that managers must assess the behaviour of critical components and acquire a sharper understanding of the impact of different decisions in order to drive improvement. Feola et al (2011) explored behavioural change of using PPE among pesticide applicators in Colombia. They suggested that changing farmers’ behaviour with respect to PPE might require considerable effort through normative pressure and participative processes.

RPE in Hong Kong

In Hong Kong, it is common for workers to use RPE to protect themselves from airborne hazards. In accordance with both the country’s Occupational Safety and Health Ordinance and also its Factories and Industrial Undertakings Ordinance, employers have a duty to ensure the safety and health of their employees at work (Labour Department, 2011).

For the use of RPE, employers should provide and maintain safe systems of work to adequately protect their employees’ safety and health. At the same time, employees need to cooperate with their employers in using RPE to protect their own health and enable the latter to comply with relevant legal requirements.

RPE is broadly divided into two types in Hong Kong: air purifying and air supplying. Air purifying respirators filter the contaminated air in the working environment when it is being inhaled by the user. They are often used when carrying out tasks where oxygen is not deficient and the levels of contaminants are not very high.

Air supplying RPE, on the other hand, provides uncontaminated air from an independent source to the user. It includes self-contained breathing apparatus which provides air from a gas cylinder, and compressed air line breathing apparatus which provides uncontaminated air from a source through a long hose. In protecting workers from airborne hazards, a high priority should be accorded to engineering measures which effectively control the contaminants at their source or, failing that, at their transmission.

RPE should only be used as the last line of protection, when residual risks still remain after all reasonably practicable control measures have already been taken.

The commissioner for labour has approved a list of RPE products that should be used for protecting workers against asbestos dust under the Factories and Industrial Undertakings (Asbestos) Regulation.

They are grouped into five categories:

• Disposable half face particulate respirators
• Half face particular filter (cartridge) respirators
• Full face particular filter (cartridge) respirators
• Powered air purifying respirators
• Supplied air respirators

A list of breathing apparatus has also been approved for use in confined spaces under the Hong Kong Factories and Industrial Undertakings (Confined Spaces) Regulation.

According to the Construction Site Safety Handbook for Public Works Programmes (Works Bureau, 2000), suitable RPE should be worn when conducting the following construction processes:

• Sanding and rubbing down wood, filling materials and old paint
• Spray painting
• Steam cleaning
• Cleaning cooling coils and filters with high pressure jets
• Working with asbestos or asbestos based products, lead and harmful or toxic chemicals in open vessels
• Working with materials that may give out silica dust or mercury vapour

The Handbook also stipulates that the correct RPE must be worn in atmospheres that contain nuisance, harmful or toxic dusts or gases, when working in confined spaces, and for rescue purposes.

Of course, necessary training should be provided to all persons on the correct fitting, use and limitations of RPE, as well as in how to recognise symptoms of exposure.

The high risk construction industry recorded 3,160 industrial accidents in 2012 and the industry recorded the highest number of fatalities and accidents of all industry sectors (Labour Department, 2013). When money or work schedules are tight, it appears that contractors may try to cut corners on site safety.

To encourage contractors in Hong Kong to adopt good safety practises when working on public contracts such as housing, there are incentive schemes under which the contractors can be reimbursed if they adopt good practises on site. The country’s Occupational Safety and Health Council also offers various sponsorship schemes for small and medium enterprises, giving financial assistance where work safety improvements are made.

Situations requiring RPE

Before introducing RPE into the workplace, employers should set up and implement a respiratory protection programme to properly manage the provision and use of RPE, based on the individual safety management systems.

Sometimes, however, workers fail to comply with the requirements. This is often the case among construction workers in Hong Kong. Training or education may be claimed to be useful for fostering behavioural change, but it seems that it should not be regarded as the only factor to induce such change. Indeed, there are still various factors that may influence the workers to change their behaviour.

The Health and Safety Executive (HSE) of the United Kingdom published a practical guide on RPE at work (HSE, 2013) and specified many factors that may affect the workers when selecting and wearing RPE. Some factors include work rate, wear time, vision requirements, temperature, humidity and mobility. In Hong Kong, the comparable hot, humid and confined work environment when on a construction site can discourage workers from wearing RPE. In some circumstances, workers may behave according to the social standards set by their peers (Feola et al, 2011). They tend to conform to the most common behaviour in the work sites, reinforcing failure to wear RPE as the ‘normal’ behaviour.

History has proven that the safest workplaces are also the most productive, but there are still many companies that continue to cut corners by putting workers’ lives at risk for the sake of higher profits. Cooke and Rohleder (2003) advocated that there is a causal loop relationship showing the balance that must be maintained between productivity and safety. Short term pressures to maintain the production schedule may cause risky shortcuts to be made, or unsafe conditions or acts to be tolerated.

Chartered safety and health practitioners from the Institution of Occupational Safety and Health’s (IOSH) Hong Kong branch have created a loop diagram, right, based on system dynamics, to assist in understanding the behaviour patterns mentioned previously. In this diagram, variables have been connected by arrows denoting the causal influences between them for systemically identifying, analysing and communicating a feedback loop structure (Richardson, 1986). Each causal link was assigned a polarity to indicate how a dependent variable was impacted when an independent variable changes. As illustrated in the following stock-and-flow diagram, positive or reinforcing loops tended to reinforce or amplify whatever was already occurring, while negative or balancing loops counteracted and opposed change.

The conceptual causal loop diagram representing the dynamic behaviour of using RPE in the construction sites in Hong Kong was brainstormed as shown in Figure 1. A focus group of IOSH’s Hong Kong branch identified a few key reinforcing loops that may produce vicious circles and ultimately snowball the undesirable consequences of particular situations. All constituents of the entire causal loop diagram were only accepted as valid if there was 90 percent agreement within the focus group.

Heinrich (1936) has long advocated in Domino Theory that the removal of the central factor of unsafe conditions and unsafe acts can prevent accidents and injuries. As shown in Figure 1, industrial accidents arise continuously at a rate determined by the unsafe conditions and acts, and they will usually hurt productivity and eventually increase productivity pressure. This causes more pressure on the commitment of management to health and safety, as represented by the first reinforcing loop (R1), which indicates that more productivity pressure leads to poor safety performance. If the management’s commitment to health and safety is strong, an organisational safety culture can restrain the productivity pressure and risky shortcuts.

The willingness to use RPE properly depends highly on safety behaviour. This behaviour is influenced by personal awareness of health and safety in a company, which is propelled by the management’s commitment to health and safety. It is identified in Figure 1 that the provision of peer pressure in practising health and safety, and adequacy of training and experience sharing, can help reinforce the positive behaviour of using RPE properly on site, as represented by the second reinforcing loop (R2). Some suitability factors such as work nature, temperature, humidity and mobility, however, can influence the decision to use RPE onsite, along with the cost of RPE and provision of monitoring.

Some workers tend to accept a certain level of adverse health as ‘normal’. The level of personal tolerance is built up by unsafe conditions and unsafe acts onsite and will eventually cause work related health deterioration. It is an undeniable fact that workers with health conditions and those at high risk from problems definitely affect productivity levels, which leads to productivity pressure (Mitchell and Bates, 2011).

This additional reinforcing loop (R3) should be counteracted by the positive culture of wearing RPE at work, established by the good behaviour of using RPE properly. It takes time for the cultivation of another reinforcing loop (R4), and this can be propelled through various incentive schemes, reward systems or initiatives by clients, government bodies and professional institutions.


RPE is vital in many workplaces to protect workers against harmful fumes and contaminants. Despite the strides we have made in our community to reduce respiratory hazards in Hong Kong, our work is not finished as there are still many occupational related diseases. Regardless of the statutory and regulatory requirements imposed on construction sites for the proper selection, use and maintenance of RPE, there are still factors that influence the workers to properly use the protection available on the country’s construction sites.

The system dynamics approach can complement other methods in understanding behaviours concerning the use of RPE. It may also help to explore possible ways of cultivating positive health and safety behaviours.

For this feature, a specially convened focus group of local experts in IOSH was established for the brainstorming and development of the generic system dynamics model. Although a series of simulation exercises should be performed, the model suggests that changing workers’ behaviour towards using RPE might require cooperative efforts in a number of areas. Safety culture of wearing RPE on site should be reinforced by incentive initiatives or reward schemes to encourage good behaviour.

Local suppliers should consider various suitability factors when designing RPE for the Hong Kong work environment. A reduction in the price of RPE, for example, may cause an increase in the number of workers with access to the correct equipment. If wearing RPE is seen as ‘normal’ on sites, then it is more likely that all workers will comply - in fear of being the odd one out.

Certainly, it would not go amiss for government bodies and professional institutions in Hong Kong to promote the use of RPE widely. Knowledge sharing of good practises is helpful for imbuing good safety behaviour. A reasonable and realistic work schedule can relieve productivity pressure so as to reduce the dangers of cutting corners and putting workers’ lives at risk for the sake of finishing projects on time.

As these discussions are based on arguably narrow data samples, this imposes some limitations on the findings. Further studies targeting a wider range of data and more real cases can serve to improve the generic simulation capability of the model.

Good health and safety will always play an important part in driving efficiencies, reducing lost work days, and sustaining a thriving business. No one can simply shrug their shoulders and say that little can be done about respiratory protection. It is necessary to develop insight when striving for a balance to sustain our occupational health in hazardous industries.

Published: 03rd Mar 2014 in OSA Magazine


Dr Sammy Wan

Dr Sammy Wan received his PhD from the University of Hong Kong. He specialises in the evaluation of industrial strategies in construction engineering and has published numerous articles and technical papers in this area.

Dr Wan is a qualified engineer, quality professional, environmentalist, and safety and health practitioner and is now the head of quality, safety and environment of the Analogue Group of Companies. As part of his work within the industry, he has been serving extensively on several study groups, task groups and public committees in Hong Kong.

He is the immediate past chairman of IOSH’s Hong Kong branch and the former president of the Hong Kong Chapter of Institute of Industrial Engineers. He is currently the chairman of the Electrical and Mechanical and the Vehicle Maintenance Service Trade Committees of the Occupational Safety and Health Council.

Dr Wan was the recipient of the first place award in the construction division paper competition of the Institute of Industrial Engineers in 2009 and received the award for best paper at the 2011 Asian Network for Quality (ANQ) Congress. He was also awarded the IOSH President’s Distinguished Service Award in 2013. In 2013, Dr Wan became one of the experts in the field of industrial engineering of the Chinese Mechanical Engineering Society.

IOSH Hong Kong Branch

The Institution of Occupational Safety and Health (IOSH) is the biggest professional health and safety organisation in the world with more than 43,000 individual members.

IOSH was founded in 1945 and is a registered charity. The Institution is an independent and not for profit organisation that sets professional standards and supports, develops and connects members with resources, guidance, events and training on health and safety.

IOSH’s Hong Kong branch was founded in 1999 and is one of the leading health and safety institutions in Hong Kong. The branch currently has more than 800 members.

Dr Sammy Wan



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