Dataset description These data files contain calibrated measurements of ambient air methane (CH₄) and carbon dioxide (CO₂) mole fractions collected using a Picarro G1301 cavity ring-down spectrometer. Measurements were conducted inside a boiler room between July 25, 2024 and July 17, 2025. The objective of this measurement campaign was to characterize methane enhancements in the boiler room and produce a dataset suitable for estimating methane emissions associated with building-level combustion and gas infrastructure. File format The data files are provided as ASCII text files (CSV format) with the following characteristics: - Missing values are represented by the string "NaN". - Variables are separated by commas (,). - Records are separated by newline characters (\n). - The first line of each file contains a header row describing the variable names. - Time stamps are reported in UTC. Instrumentation Measurements were performed using a Picarro G1301 cavity ring-down spectrometer configured for continuous monitoring of CH₄, CO₂, and H₂O mole fractions. All reported gas mole fractions were: - Corrected for water vapor dilution, and - Calibrated using periodic reference gas measurements. Variables included in the dataset: - Time_utc: Time of measurement in UTC, formatted as YYYY-MM-DD hh:mm:ss.sss. - Instrument: Instrument model used for data collection (Picarro G1301). - CH4_raw_ppm: Raw ambient air methane mole fraction measured by the instrument in ppm. - CH4_dry_ppm: Ambient air methane mole fraction corrected to dry air in ppm. - CH4_calibrated_ppm: Calibrated ambient air methane mole fraction in ppm. - CO2_raw_ppm: Raw ambient air carbon dioxide mole fraction measured by the instrument in ppm. - CO2_dry_ppm: Ambient air carbon dioxide mole fraction corrected to dry air in ppm. - CO2_calibrated_ppm: Calibrated ambient air carbon dioxide mole fraction in ppm. - H2O_raw_percent: Raw ambient air water vapor mole fraction measured by the instrument in %. - H2O_reported_percent: Corrected ambient air water vapor mole fraction in %. - Cavity_Pressure_torr: Gas pressure in the instrument optical cavity in Torr. - Cavity_Temperature_celsius: Optical cavity temperature in °C. Notes on data processing - Dry mole fractions (*_dry_ppm) are computed by correcting raw wet mole fractions for water vapor dilution using the measured H₂O mole fraction. - Calibrated mole fractions (*_calibrated_ppm) are obtained by applying instrument-specific calibration factors derived from reference gas measurements. - For most scientific analyses, including emission estimation, calibrated dry mole fractions should be used.