Home environment" could refer to the conditions where you live. The indoor air quality in your home could be degraded by second-hand smoke, formaldehyde outgassing from new furniture or carpets, or contamination by mold spores. That same indoor air could be purer than outside because of the filtering effect of plant foliage (removing particles and CO2). Your water quality could be negatively affected by lead leaching from the pipes or positively affected by a water filter.