Data from: Indoor air quality in California homes with code-required mechanical ventilation

Data were collected in 70 detached houses built in 2011-2017 in compliance
with the mechanical ventilation requirements of California’s building
energy efficiency standards. Each home was monitored for a one-week period
with windows closed and the central mechanical ventilation system
operating. Pollutant measurements included time-resolved fine particulate
matter (PM2.5) indoors and outdoors and formaldehyde and carbon dioxide
(CO2) indoors. Time-integrated measurements were made for formaldehyde,
NO2 and nitrogen oxides (NOX) indoors and outdoors. Operation of the
cooktop, range hood and other exhaust fans was continuously recorded
during the monitoring period. One-time diagnostic measurements included
mechanical airflows and envelope and duct system air leakage. All homes
met or were very close to meeting the ventilation requirements. On average
the dwelling unit ventilation fan moved 50% more airflow than the minimum
requirement. Pollutant concentrations were similar or lower than those
reported in a 2006-2007 study of California new homes built in 2002-2005.
Mean and median indoor concentrations were lower by 44% and 38% for
formaldehyde and 44% and 54% for PM2.5. Ventilation fans were operating in
only 26% of homes when first visited and the control switches in many
homes did not have informative labels as required by building standards.