Stable library from PyPi:

• Just run sudo pip install pms5003

Latest/development library from GitHub:

• git clone https://github.com/pimoroni/pms5003-python
• cd pms5003-python
• sudo ./install.sh

The serial port on your Raspberry Pi must be enabled:

# Disable serial terminal over /dev/ttyAMA0
sudo raspi-config nonint do_serial 1

# Enable serial port
raspi-config nonint set_config_var enable_uart 1 /boot/config.txt

And additionally be using a full UART (versus the default miniUART):

Add the line dtoverlay=pi3-miniuart-bt to your /boot/config.txt

This will switch Bluetooth over to miniUART, see https://www.raspberrypi.org/documentation/configuration/uart.md for more details.