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Why are masks recommended for outdoor workers at lower PSI than for the general public?

The threshold for usage of N95 masks or equivalent for protection of outdoor workers is suggested at lower PSI than for the general public as work commitments may require prolonged outdoor exposure or strenuous work on a regular basis. Employers should refer to the MOM guidelines for more details on situations where suitable masks or respirators have to be used. In general, work arrangements to reduce outdoor work such as frequent breaks and job rotation should be made to reduce prolonged or strenuous outdoor work. Use of mechanical aids such as trolleys, lifts or hoists instead of manual lifting and carrying could also reduce the strenuous nature of these activities.

Where outdoor work is unavoidable, employers should provide suitable masks (based on the MOM’s guidelines) to protect workers.

If N95 masks are used, employers and employees should note that these increase the effort of breathing. For some employees, this may cause discomfort in breathing, tiredness or headache. This may be due to their masks causing increased resistance to breathing, and a reduction in the volume of air breathed. Employers should consider instituting regular breaks and encourage hydration of employees using masks. Risk assessment, taking into account the usage of the respirators, individual employee’s heath conditions and nature of outdoor work must be conducted.

Last Updated: 16 September 2015