If you using clean lead you shouldn't have much of a problem. Lead poisoning comes from ingestion most of the time and the reason is simple. Lead does not produce fumes or vapor below 1200 degrees, if you have any smell it is usually impurities and good ventilation is sufficient to carry out the fumes if you are using good lead. I get most of my lead from Rotometals , 99% pure and 3% -5% antimonial and with 2 windows open and a fan blowing in between to create good air circulation there are no problems. I had a serious illness and since then I have to have my blood checked on a regular basis and one thing I have the doctor check for is the lead levels in my blood, in more than 20 years of pouring I can say that I'm fine but, if you are melting down wheel weights or old lead pipes and other forms of scrap lead well then I'd be outside or I'd have a hood and exhaust fan. It also pays to be cautious and a good exhaust fan and hood is something I think is beneficial if pouring indoors but if you aren't pouring for 6 to 8 hours a day a shop that isn't confined with good ventilation will work as long as you are using clean lead.