Measurement of gases

Apparatus comprising:

• an instrument adapted for measurement of one or more target gases in a sample of ambient air, further comprising:
• an input for the sample of ambient air,
• a first path having a first inlet and a first outlet,
• at least one additional second path having a second inlet and a second outlet,
• at least one multiple-way valve having a first input port connected to the first outlet, having a second input port connected to the second outlet and having an output port,
• a connection connected to the output port,
• a electrochemical gas sensor connected to the connection for receiving the sample of ambient air,
• a humidity buffer directly connected between the output port of the multiple-way valve and the electrochemical gas sensor,
• a flow inducer connected to the instrument for flowing the one or more target gases with the sample of ambient air in the first and the second paths through the multiple-way valve, the connection and the electrochemical gas sensor,
• a selective gas scrubber in the second path for removing a target gas from the sample of ambient air,
• a gas flow divider configured as a T having an inlet gas flow port at a bottom of the T and an outlet gas flow port at a top of the T for selectively supplying the sample of ambient air to the first input port or the second input port, and
• wherein the bottom of the T is connected to the input for the sample of ambient air and wherein one end of the top of the T is connected to the first inlet and another opposite end of the top of the T is connected to the second inlet.