....feeling sick

There are plenty of people who don't realize the dangers of hydrogen sulfide. Maybe his boss doesn't even know. A proper respirator for H2S looks to be scuba gear... a regular paint respirator isn't going to cut it.

Ever have a battery go bad and smell like rotten eggs? Apparently that can kill you too.

Hydrogen sulfide inhalation killed mother, toddler found on Florida's Turnpike in June

 

I've been pumping grease traps for about a year and a half and I've never felt sick the way you're describing and I've never worn a respirator. Yeah, the first few days or even first couple weeks the smell is pretty overwhelming but honestly I don't even smell it anymore. Honestly, the best part of my day is watching people get sick to their stomach while I'm pumping the grease trap haha!
It looks like you're just pumping the small inside grease traps. Try pumping industrial sized grease traps. I have one location that I pump every 3 months and it's a 10,000 gallon grease trap! Yeah, I said 10,000 gallon grease trap!! It's at a fancy high class Hotel/Restaurant. I love watching those upper class people look like they want to hurl and giving me the stink-eye like I ruined their vacation hahaha!

I skimed through this thread but if you have any questions you want to ask me, feel free.

 

Yep, I service my local McDonald's and it stinks up the whole parking lot. Better yet pump a grease trap like Denny's that's open 24 hours and watch people leave the restaurant in disgust.

 

I service small grease traps and industrial-size grease traps.

To service an industrial-sized grease trap you have to pop off the big manhole covers, then I use a crust buster to stir it all up and then I stick a 4 inch vacuum hose in the tank and pump it out with the vacuum truck

 

Not too sure what you mean. Very few restaurants in my town have basements. Do you have a picture for an example?