The House Observations of Microbial and Environmental Chemistry (HOMEChem) study is a collaborative field investigation designed to probe how everyday activities influence the emissions, chemical transformations and removal of trace gases and particles in indoor air. Sequential and layered experiments in a research house included cooking, cleaning, variable occupancy, and window-opening. This paper describes the overall design of HOMEChem and presents preliminary case studies investigating the concentrations of reactive trace gases, aerosol particles, and surface films. Cooking was a large source of VOCs, CO₂, NO_x, and particles. By number, cooking particles were predominantly in the ultrafine mode. Organic aerosol dominated the submicron mass, and, while variable between meals and throughout the cooking process, was dominated by components of hydrocarbon character and low oxygen content, similar to cooking oil. Air exchange in the house ensured that cooking particles were present for only short periods. During unoccupied background intervals, particle concentrations were lower indoors than outdoors. The cooling coils of the house ventilation system induced cyclic changes in water soluble gases. Even during unoccupied periods, concentrations of many organic trace gases were higher indoors than outdoors, consistent with housing materials being potential sources of these compounds to the outdoor environment. Organic material accumulated on indoor surfaces, and exhibited chemical signatures similar to indoor organic aerosol.

We spend most of our time in built environments. The cumulative exposure to particulate matter (PM) occurring in these built environments can potentially be comparable to or even exceed that occurring outdoors. Therefore, it is critical to understand the sources, dynamics, and fate of PM in built environments. This work focuses on aerosol dynamics modeling (including coagulation, deposition, and exfiltration) of sub-500 nm particles measured inside a test house during the HOMEChem campaign while performing prescribed cooking activities. Deposition characteristics of the test house, emission rates and factors, and the fate of particles are presented. Number emission rates calculated for two different heat sources (stove and hot plate) and the various meals cooked on them were highest for sub-10 nm particles. Coagulation and deposition contributed comparably to the particle number concentration decay. Most of the PM (90% number-based and 70% mass-based) deposited within the house while the remaining fraction left the test house volume via exfiltration. Simulation results show that while increased air exchange rate reduces indoor PM mass concentration, it can lead to increased number concentration. An increase from 0.5 to 5 ACH (comparable to the equivalent air change rate from running a well-dimensioned portable air cleaner) would result in a 70% reduction in PM mass-based exposure while a further increase from 5 to 20 ACH would only result in an additional 21% reduction.

Inhalation of particulate matter is associated with adverse health outcomes. The fluorescent portion of supermicron particulate matter has been used as a proxy for bioaerosols.The sources and emission rates of fluorescent particles in residential environments are not wellunderstood. Using an ultraviolet aerodynamic particle sizer (UVAPS), emissions of total and fluorescent supermicron particles from common human activities were investigated during the HOMEChem campaign, a test‐house investigation of the chemistry of indoor environments. Human occupancy and activities, including cooking and mopping,were found to be considerable sources of indoor supermicron fluorescent particles, which enhanced the indoor particle concentrations by two orders of magnitude above baseline levels. The estimated total (fluorescent) mass emission rates for theactivities tested were in the range of4–30 (1–11) mg per person‐meal for cooking, and 0.1–4.9 (0.05–4.7) mg/h for occupancy and mopping.Model calculations indicate that, once released, the dominant fate of coarse particles (2.5‐10 micrometer in diameter)was deposition onto indoor surfaces, allowing for the possibility of subsequent resuspension and consequent exposures over durations much longer than the ventilation time scale.Indoor coarse particle deposition would also contribute to soiling of indoor surfaces.

We deployed multiple low-cost air quality monitors to investigate the transport of kitchen-generated fine particulate matter (PM_2.5) into the bedrooms of four homes of different sizes over a period of more than nine weeks at each home.

Black carbon and brown carbon emissions were investigated for different indoor activities and during periods of no activity in a test house as a part of the HOMEChem study.