Spatiotemporal characterization of irradiance and photolysis rate constants of indoor gas‐phase species in the UTest house during HOMEChem

Abstract

Photochemistry indoors has recently been recognized as an important factor affecting indoor air quality. A number of studies have shown that gas phase photochemical reactions can affect the oxidative capacity of the indoor environment by forming radicals: Gomez Alvarez et al. reported elevated hydroxyl radical (OH) levels in a sunlit classroom from nitrous acid (HONO) photolysis indoors, 1 and Lakey et al. reported enhanced OH radicals during bleach cleaning that can be largely explained by a cascade of reactions initiated via molecular chlorine (Cl 2 ) photolysis. 2 Gas-phase oxidant precursors such as formaldehyde (HCHO) and hydrogen peroxide (H 2 O 2 )have also been predicted to photolyze under illumination by indoor sunlight and electric lighting to form OH radicals, 1,3-10 whereas nitryl chloride (ClNO 2 ) and hypochlorous acid (HOCl) released during the use of sodium hypochlorite bleach-based cleaners can be photolyzed by indoor light leading to the production of Cl atoms that react efficiently with most volatile organic compounds (VOCs). 5,11,12

Environmentally persistent free radicals in indoor particulate matter, dust, and on surfaces

“…The high concentrations on windows could be influenced by the increased photochemical EPFR production via transmitted solar radiation, which is highest on/near windows, and leads to greater rates of OH generation, photolysis of photolabile compounds, and possible photosensitized reactions. 17,45–49…”

“…The high concentrations on windows could be influenced by the increased photochemical EPFR production via transmitted solar radiation, which is highest on/near windows, and leads to greater rates of OH generation, photolysis of photolabile compounds, and possible photosensitized reactions. 17,[45][46][47][48][49] The total dust samples (i.e. loose dust under furniture) analyzed separately also had substantial EPFR (2.0×10 10 spins µg -1 ).…”

Reactive Chlorine Emissions from Cleaning and Reactive Nitrogen Chemistry in an Indoor Athletic Facility

“…Rate coefficients were calculated using measured photon fluxes, along with reported absorption cross sections and quantum yields (Text S2). ,− Although the spectrometer fiber optics collect light from multiple angles, we do not account for any spatial differences in photon fluxes, which have been shown to occur indoors. , Loss and production rates of NO 3 were also determined. For NO 3 , the formation was by and , along with losses by , , (as limonene, one of the most abundant organics measured in the room and among the most reactive with NO 3 ), ,, and .…”

Measurements of Hydroxyl Radical Concentrations during Indoor Cooking Events: Evidence of an Unmeasured Photolytic Source of Radicals

“…Photon flux from windows was measured with an Ocean Optics USB4000 spectrometer equipped with a cosine corrector. 31 This spectrometer was located on top of the OH instrument for the two cooking episodes examined. Photon fluxes were used to calculate photolysis rates of relevant indoor species.…”