Tara Parker-Pope

If you attend a social event and find yourself in close conversation with someone from outside your household, even outdoors, wear a mask. Keep music levels low so people don’t have to shout. (Loud speaking expels more droplets than a quiet voice.) Don’t share food or serving utensils.
By Tara Parker-Pope
https://www.nytimes.com/2020/07/03/well/live/coronavirus-spread-outdoors-party.html