Hello again, everyone. I'm a little confused. My setup is: RPi Zero 2 W + mcp3008 (adc) + MQ-135 (gas sensor).
I successfully run program that read sensor value in Python. (There are examples)
Now I also successfully run similar program in Rust.
But values I get different. 
For Python it's 7000-30000 range. For Rust is 70-900.
I know that for Python I need to interpret value that I get, and for Arduino I don't. And maybe Rust already doing a good job, but sensor says that I have ~75 PPM, that is not possible. At least I think.
For Rust I use this crate: https://github.com/thecodechemist99/adc-mcp3008/ 
For Python this: https://github.com/adafruit/Adafruit_CircuitPython_MCP3xxx