'Return Dust value.'

@property
def state(self):

    if self._device.environmental_state:
        temperature_kelvin = self._device.environmental_state.temperature
        if (temperature_kelvin == 0):
            return STATE_OFF
        if (self._unit == TEMP_CELSIUS):
            return float('{0:.1f}'.format((temperature_kelvin - 273.15)))
        return float('{0:.1f}'.format((((temperature_kelvin * 9) / 5) - 459.67)))
    return None
