My company is considering using the BME280 to measure temperature/humidity in a gas path which will contain potentially corrosive gases. The conerns are mainly with nitric oxide (NO), nitrogen dioxide (NO2), and nitric acid (HNO3). Are there any studies available on the chemical resistance of the BME280 to such chemicals? If not, it would be useful to know the materials which will be exposed to the air. What is the "metallic case" made of? What parts of the internal circuit are exposed to the sample hole?