In beach climate zones, salt particles in the air corrode metal and degrade other materials, and this is enhanced if the climate has lots of sunshine.
Small particles are also a significant human health hazard. Individuals with respiratory issues can have severe reactions, including asthma attacks which can be life threatening. These salt particles are specifically intended to be very small so they can stay in the air and travel long distances, making the geographic footprint even greater.
This is a horrible experiment to perform in an urban area. It is dangerous and possibly illegal. The agencies that fund this kind of work have well defined protocols addressing the human impact of experiments, and there is no way this would have been approved if the work had been correctly evaluated. Someone was negligent, cut corners or deliberately ignored the rules. Whoever is responsible will be in big trouble, like having the project canceled, being excluded from getting grants, or being fired trouble.
Before HD camera were in cellphones and doorbells I worked on a project with a 720p camera. It was big, cost well over a hundred thousand dollars, and was very rare. When testing the camera it was decided we would not take pictures out of the windows since we could capture images of people walking outside. The protocol for the funding agency had very strict guidelines about human experimentation and we didn't want to have any problems. For motion image tests we bought some lava lamps and other electric motion toys so it was manifest that people were not experimental subjects.