I frequent both indoor and outdoor ranges. Indoor ranges obviously have the advantage of being sheltered from bad weather and other outdoor inconveniences like mud and insects. Also the indoor ranges I frequent have targets hanging on mechanized tracks, whereas the outdoor ranges have hot / cold periods for hanging new targets, which eats into your shooting time. The local outdoor range I frequent has the advantage of multiple spacious bays with different types of steel targets, which for me are the most enjoyable targets to shoot with my CZ pistol or plink with my .22 rifle. There are generally also longer distance targets available, although we now have a local indoor range with a 100 yard rifle range, which is plenty far enough for me.
There are several indoor ranges in my local area. One is old and dirty with poor ventilation. I don't go there. All the rest are relatively new, clean, and claiming to have state-of-the-art ventilation systems that recycle the air X number of times per hour and filter down to Y size particles.
As far as lead, these indoor ranges with their industrial strength HVAC systems are designed to suck lead gas and other bad stuff downrange towards the berm. As far as COVID-19, some of these same ranges claim that these same systems will filter airborne droplets that may be carrying a virus out the same way they filter out lead and other contaminants. That may be true, but unlike the gases coming out of your firearm at the firing line, the stuff coming out of the cluster of people standing behind you and talking, caughing, etc. is going to get pulled right over you on its way downrange.
Of the two different indoor ranges I have been to since the COVID-19 thing happened in the Spring, they both have notes on the front door saying masks are mandatory, then you get inside the lobby area and find usually half of the customers, but none of the employees or the owner, actually wearing masks. Once you are out on the range, then there are even fewer people wearing masks. You can debate the actual risk of catching this virus, but for above-mentioned reasons I don't think their HVAC system provides any magical protection from airborne droplets coming out of maskless people standing behind the firing line, so I wear a mask.
Back around May I decided that I should probably go and see how I would do with my pistols while wearing nitrile gloves and a mask. So I went and tested that. I got premature slide lockback as a left-handed shooter because the glove was interfering with the slide lock.
Back on the subject of lead, another thing I do is I keep an old pair of shoes in a plastic bag, and my range bag, both in a plastic tote. At home these items stay in the tote. When I go to the range, the tote goes into the trunk of the car. When I get there, I change my shoes in the parking lot. When I leave, I change back into my regular shoes before driving home. I also have lead removal wipes in my range bag, and lead removal hand soap and shampoo at home for after I return.
At the outdoor range I don't feel the need to wear a mask if I don't have anyone other than my household members nearby me, which is usually the case. Of course there's the one odd RSO who wants to come over maskless and chit chat for some reason totally unrelated to our safe use of the range. Normally I would be receptive to this but not at the moment. So I tell my sons to keep their masks handy and mask up when we see him coming. He seems offended and leaves. That's alright I guess. If we aren't doing anything unsafe, and he isn't calling a cease fire, then he doesn't need to tell us anything.
Anyway, I don't know all of the regulatory details, but I thought OSHA or some similar agency regulated lead levels at gun ranges. Either way I manage my own lead exposure risks by not going into indoor ranges with stale air and decrepit old HVAC systems, not tracking lead on my shoes through my car or home, and not eating or drinking on the range or with unwashed hands after shooting.
I'll mention another funny thing. When I go shopping I wear a mask, which is mandatory, and I also wear a set of 3M safety glasses. So I'm walking around Walmart or Kroger with this stuff on, also strapped with my P-07 and extra mag. If I popped in some ear pro and put on my lead-contaminated shoes, I'd be range ready. God Bless America.