[Mick]

Most transmission is indoors. 
Masks help. A lot. 
There are certainly going to be some cases from outdoor transmission, but the physics of particle flow make it much less likely. I'll bet most of the "backyard barbecue" transmission involved going indoors while attending or very close contact without hand washing or masks. I don't think outdoor activities need to be banned IF people wear masks and they keep a few feet of distance. Hard to wear a mask while eating, though.

I live in Willow Glen in San Jose, and we have a three-block downtown.  The restaurants have opened up for outdoor dining.  Some had porches/patios already, some commandeered a portion of the street or the broad sidewalks.  It's interesting...some of the restaurants have gone to some elaborate lengths to create an "indoor" setting with elaborate awnings.  Some have clearly spaced tables 8-10 feet apart.  Some have placed tables essentially back to back outdoors.  I don't know what the statistics are, but I won't dine in a restaurant that has tried to replicate an "indoor" setting, nor at the restaurants where the tables are outdoors but are back to back.

[Mick]

Most transmission is indoors. 
Masks help. A lot. 
There are certainly going to be some cases from outdoor transmission, but the physics of particle flow make it much less likely. I'll bet most of the "backyard barbecue" transmission involved going indoors while attending or very close contact without hand washing or masks. I don't think outdoor activities need to be banned IF people wear masks and they keep a few feet of distance. Hard to wear a mask while eating, though.

I live in Willow Glen in San Jose, and we have a three-block downtown.  The restaurants have opened up for outdoor dining.  Some had porches/patios already, some commandeered a portion of the street or the broad sidewalks.  It's interesting...some of the restaurants have gone to some elaborate lengths to create an "indoor" setting with elaborate awnings.  Some have clearly spaced tables 8-10 feet apart.  Some have placed tables essentially back to back outdoors.  I don't know what the statistics are, but I won't dine in a restaurant that has tried to replicate an "indoor" setting, nor at the restaurants where the tables are outdoors but are back to back.