They shouldn't be condensed into smaller areas, they should be at home
Outside exercise is listed as an allowable activity in every state. Leaving aside whether you think this is the right thing to do or not (and personally I think it's very important for health and well being), because it's permitted then sensible provision needs to be undertaken to allow it to happen. Blanket closures are potentially counter productive. Here's an example, and yes it's a personal one so I have skin in the game, but I'm happy to be convinced if I am being illogical.
I live in Coningham, Tasmania, and over my back fence is the Coningham reserve, a 1000+ acre recreation area managed by Tas Parks and Wildlife. When I say managed, they look after the external signage and have a description of the reserve on their website, and they send a patrol around probably twice per year. Any on ground management (weeding, tree planting, trail maintenance) is undertaken in collaboration with Parks (i.e we tell them we want to do something and they assist) by the Friends of Coningham Landcare group and the Coningham Mountain Biking Club, both of which I am a member. The reserve has no picnic or camping grounds, toilets, gates to open, hand rails, and multiple access points, none of which are large car parks. So zero touchy surfaces to transmit droplets (unless you are the sort of walker who goes out of your way to touch every tree you walk past), and limited spots for groups to congregate. If I go for a walk or a bike ride in the reserve on an ordinary day I would be lucky to see one other person. However because it is Parks land it is now closed.
Less than 100m away at some points is a coastal reserve trail managed by the local council. It's a pretty narrow strip of land, mostly around 50-75 metres wide with a single trail running between a few small beaches. There's a toilet block at one beach and a few picnic tables and benches at several locations on the trail. This is still open, and friends of mine who's properties border this trail, estimate that foot traffic on it has tripled since the reserve closed. I've walked it a few times with the kids since closure and have run into several people both times.
The local roads have no footpaths, and it being quite a bushy and hilly area, nature strips bordering the roads are basically non existent. So in summary the options to undertake a listed allowable activity are as follows:
1: Walk/ run/ bike ride down the middle of fairly hilly roads. Unattractive at best, and with little kids potentially dangerous.
2: Walk/ run/ bike/ do beach activities using access points that limited, have surfaces for COVID transmission, and now see very frequent visitation.
Or I can:
3: Walk/ run/ bike ride in a 'closed' reserve where contact with other people is extremely unlikely (even if it was open) and surfaces for droplet contamination essentially don't exist
What do you think is the safest option?
- The virus remains viable for hours in the air. you can be out in yhe middle of nowhere and still transmit it to anyone that walks through yhe space in the next few hours. Therefore one could not possible "guarantee" anything in that regard. It certainly isn't 100% safe
I am interested to know where you have seen this information as what you are described is aerosol based transmission and there is
no evidence that COVID-19 is transmitted in this fashion