This is why simple balances are such a brilliant idea despite their simplicity. You don't need to calibrate to the local conditions, if I have a 250g mass on one side, and I put something on the other side and it balances, that's 250 grams, done. Only the (often provided with the balance) prototype masses need to be calibrated and that can be done by experts far from your local environment.
Until as recently as 2019 this approach - using a prototype - was the only extant mass definition, the prototype kilogram lived at a specialised laboratory and its clones were used around the world to define mass (yes including the pound if you're an American).
[ Today instead the Planck constant is defined to be exactly 6.62607015×10^−34 kg x m^2 per second and it's possible to build devices such as a Kibble balance to estimate what the kilogram is from knowing this definition, the better your Kibble balance the better the estimate ]
Until as recently as 2019 this approach - using a prototype - was the only extant mass definition, the prototype kilogram lived at a specialised laboratory and its clones were used around the world to define mass (yes including the pound if you're an American).
[ Today instead the Planck constant is defined to be exactly 6.62607015×10^−34 kg x m^2 per second and it's possible to build devices such as a Kibble balance to estimate what the kilogram is from knowing this definition, the better your Kibble balance the better the estimate ]