SGP/PGS/C1 - Suspicious 4m data

KNF pump for 4m height (channel 2) started to leak on November 24, 2004 and sampled air 
was consequently "contaminated" by indoor air. The pump was replaced on August 19, 2005.

Either use another sampled height (25m, or 60m) or use data with caution.

• calculated concentration of CO2(co2ppm)
• 90% confidence limit of co2ppm(co2ppm_se)