Bizarre idea a motorcycle helmet as virus defense.
I'm a magnificant virus detector since I can catch a cold standing in line at a store, when nobody sneezes or coughs. I used to get 10 respiratory diseases a year when I worked. I'm down to about 3 a year when in only do volunteer work with one other guy. I'm the grandson of a half native american guy that died of a bad cold age 44. The other side had Native Am history, too. Since I don't get out much since I quit work, I know where I got things by the 36-48 hour rule. 3 - 4 days after I'm out somewhere, If I come down with a fever, where I was 3-4 days ago was the source. Stores, busses, Amtrak, Airports or airliners, church, restaurant buffets.
The droplet in the air theory applies IMHO, to Europeans, Africans, Asians. I just need a few virus in the air to catch something. A virus will blow right through a M95 mask, and around the bottom of any helmet not a sealed respirator. The only safety would be nerve gas tight masks, like the Army uses, and those are not specified against viruses, only nerve and tear gas. I'm not wearing a mask. I am keeping away from other people, at least until the sun burns this off in May or so. I very rarely catch a fever in the summer.
Best defense against virus is the wind, outdoor space. The large volume cuts the number of particles per breath. I don't catch viruses outdoors. The 6' space rule is quite useful.
Due to my history, I've developed quite a concious management of the touching my face reflex. I do it, but I touch my face with my right hand. I handle door handles, money, surfaces, with the left hand. I find toilet rooms particularly problematic, and don't touch anything in one. I wear long sleeves so I can do door handles and faucet handles as required without touching them.
The covid-19 is a virus like any other, the same size as the common cold. The difference is, it kills 100 to 300 times more people that get it than flu does. I would expect my experience with cold & flu viruses would predict the maximum risk of catching it, in most circumstances. So my advice is, get out and ride the bike, walk the dog, jog, whatever. Stay 2 m away from other people. Don't touch anything, or if you do, don't touch your face until after you've washed the hands. Wash fresh vegetables, most other food in packages I find non-infectous. Buffets have always been a problem for me, especially "family " style dinners, where people use their personal utensils to get food out of the serving plate. I frequently get a cold 3 days after such events, unless I limit myself to dishes kept extremely hot - 140 deg.
The unfortunate thing about "shelter in place" rules, apartment ventilation systems don't filter out viruses. The experience of the 460 patients who caught covid 19 on the Diamond Princess would be fairly typical of apartment dwellers. Indoors is dangerous if other people are in the same ventilation system.
The cool thing about aerobic exercise, it builds your lung capacity so that you might not need a ventilator when your lungs fill up with fluid. Having been diagnosed with "walking" pneumonia 8 times and having similar diseases 20-25 times, I work out relentlessly. I ride the bicycle everywhere without power unless the wind is >12 mph in my face. Come up yourself with some sort of aerobic routine. Read Dr. Ken Cooper's book(s). As I caught a cold in the gym, I do not recommend them. Too many people, not enough space. The governor in KY closed them, good idea IMHO. I'm glad most people do well in public pools. I caught a cold nearly every summer I got in one, quit pools age 16. The ocean is okay, for some reason. Never caught a cold at Galveston or Freeport.
Too late now, but get the pneumonia shot. I haven't had a bacterial lung infection since the 13 valent one came out. Only viruses. 7-10 day recovery instead of 3-4 weeks with the bacterial after infection.