There is a downside to scaremongering on pollution, especially for us walkers. If you take one of the prime arguments used for keeping people out countryside used by those, who have been conditioned to argue against public access, is the increase of cost of insurance against public liability. Although the level of actual risk is very low, being prepared to allow access beyond the RoW network, is actively lobbied against.
The more we think there is a risk the more that lobby will play on those fears, I am more likely to avoid going on an plane flight because of a likely risk of a cocktail of recycled virus and bacteria, which I know are going to affect my quality of life in the weeks to come.
Use this argument to tell the occupiers of our countryside to allow us to walk away from roadside verges, now even the most rural are cluttered by white van drivers and commuting incomers, from expensive lets landowners have made in the Victorian farm buildings, no longer wanted for agricultural use.
I had an object lesson in the use of this fear tactic some years ago. An estate manager must have acquired job lot of chemical warning notices, these were used at strategic locations around the estate together with discarded chemical containers, I knew that the particular chemicals were not likely to have been used in these locations, not many others would have known.
In lowland Scotland, I found field margins sprayed with a contact weedkiller used as a deterrent for walkers using there right of access, but that weedkiller is immediately inert on contact with the ground.