I don’t really leave the house that often, mostly to walk the dog, but I don’t then cuz it’s a huge open air space.
I do on the bus because of how confined it is and how many people use/touch it, but besides that I have no idea.
Do you always have to wear a mask in these places? Or just when there is a covid spike?
How do you even know when there is a covid spike for that matter?
Covid can hang in the air like smoke, so basically any public indoor space, and any busy outdoor space. One sick person shedding virus, whether they present as sick or not, can fumigate a small area with covid for a while. It's best to assume there's covid around even when cases are low.
A small room with a few people? I don't worry about it that much outside of covid peaks, personally, but it kinda depends on how much you trust them to not lie about symptoms or recently being around someone sick.
If peer pressure or malaise of not doing stuff gets the best of you (this happened to a few people I know who are otherwise pretty covid aware still), at the very least look into nasal sprays like betadine.
What do nasal sprays do?
They typically coat your nasal passage in with stuff that makes it hard for virus/allergens to survive. Betadine has something called iota-carageenen, which comes from seaweed, and it envelops small particles like a virus before it interact with your nasal passage and infect you. Other sprays have different formulas and do slightly different things, but essentially attempt the same type of thing. Betadine helps my allergies so in my experience I can tell it's intercepting allergens at the very least.
Not foolproof, and not a good sub for masks, but it helps your odds a bit.
And one of the ways covid can enter your brain is through the olfactory bulb in your nose, which is why so many people have long term problems with smell, so protecting that is probably a good idea.
What other nasal sprays would be helpful?
Of the ones I've had experience with, I would recommend all the iota-carageenan based sprays: Betadine, Luca V-defense, Flo Travel Spray. What little studies they've done have shown at least some effectiveness. It coats your nasal passage with a thin film of carageenan which is derived from seaweed and traps small particles like dust and virus. Super-snot, basically. Doesn't irritate the nose like other sprays do.
I've also seen generic saline sprays with iota-carrageenan added, which should basically do the same thing.
Covixyl has done animal studies that showed effectiveness, but it stings which some people don't like. I used this a lot unti they added an xylitol that irritated my nose and made it start running for an hour.
Xylitol based sprays supposedly work, but it bothers my nose so I can't vouch for them. The main brand is called Xclear. They are easy to find. Supposedly changes the ph of your nose to make it hostile to viruses. Didn't work for my friend who used it when their partner was sick, but that might just be a limitation of nasal sprays generally.
There's also nitric oxide sprays, but the main developer of those types of sprays (Enovid) is based in Israel and it's not authorized for distribution in the US so you have to import it.
There were also some evidence that the ingredient in neosporin can trigger an immune response and fight of viruses that way, with some people suggesting you take a q-tip and apply a little bit to the inside of your nose when going someplace high risk, like taking a flight or whatever. But that's anti-bacterial and probably not a good idea to do too often. If you are doing something particularly high risk, like a concert in a crowded bar or something, I would do the q-tip thing on top of a nasal spray.
But if you are exposed to a lot of virus in the air for a long duration, these probably won't be enough to prevent infection, but reducing the amount of virus you are exposed to is a good thing.