These conclusions have important policy implications in the context of creating guidelines to reduce transmission of SARS-CoV-2. Breathing produces smaller particles than singing and speaking, suggesting that vocalisation may carry higher risk than breathing if the potential SARS-CoV-2 dose delivered by an individual infected with the virus scales with particle mass. Size distributions are comparable across speaking and singing at the same volume and generate relatively similar, yet statistically significantly different, numbers of particles. Most importantly, number concentrations from speaking and singing rise in parallel with increasing volume. Given that speaking and singing produce numbers of particles of the same order of magnitude, and that increasing volume increases that number by orders of magnitude, guidelines from public health bodies should focus on the volume at which the vocalisation occurs, the number of participants (source strength), the environment (ventilation) in which the activity occurs and the duration of the rehearsal and period over which performers are vocalising. For certain vocal activities and venues, amplification may be a practical solution to reduce the volume of singing by the performers. Based on the differences observed between vocalisation and breathing and given that it is likely that there will be many more audience members than performers, singers may not be responsible for the greatest production of aerosol during a performance, and for indoor events measures to ensure adequate ventilation may be more important than restricting a specific activity.