Indoor, outdoor, and regional summer and winter concentrations of PM10, PM2.5, SO42-, H+, NH4+, NO3-, NH3, and nitrous acid in homes with and withoutkerosene space heaters

Twenty-four-hour samples of PM10 (mass of particles with aerodynamic diamet er less than or equal to 10 mu m), PM2.5, (mass of particles with aerodynam ic diameter less than or equal to 2.5 mu m), particle strong acidity (H+), sulfate (SO42-), nitrate (NO3-), ammonia (NH3), nitrous acid (HONO), and su lfur dioxide were collected inside and outside of 281 homes during winter a nd summer periods. Measurements were also conducted during summer periods a t a regional site. A total of 58 homes of nonsmokers were sampled during th e summer periods and 223 homes were sampled during the winter periods. Seve nty-four of the homes sampled during the winter reported the use of a keros ene heater. All homes sampled in the summer were located in southwest Virgi nia. All bur 20 homes sampled in the winter were also located in southwest Virginia; the remainder of the homes were located in Connecticut. For homes without tobacco combustion, the regional air monitoring site (Vinton, VA) appeared to provide a reasonable estimate of concentrations of PM2.5 and SO 42- during summer months outside and inside homes within the region, even w hen a substantial number of the homes used air conditioning. Average indoor /outdoor ratios for PM2.5 and SO42- during the summer period were 1.03 +/- 0.71 and 0.74 +/- 0.53, respectively. The indoor/outdoor mean ratio for sul fate suggests that on average approximately 75% of the fine aerosol indoors during the summer is associated with outdoor sources. Kerosene heater use during the winter months, in the absence of tobacco combustion results in s ubstantial increases in indoor concentrations of PM2.5, SO42-, and possibly H+, as compared to homes without kerosene heaters. During their use, we es timated that kerosene heaters added, on average, approximately 40 mu g/m(3) of PM2.5 and 15 mu g/m(3) of SO42- to background residential levels of 18 and 2 mu g/m(3), respectively. Results from using sulfuric acid-doped Teflo n (E.I. Du pont de Nemours & Co., Wilmington, DE) filters in homes with ker osene heaters suggest that acid particle concentrations may be substantiall y higher than those measured because of acid neutralization by ammonia. Dur ing the summer and winter periods indoor concentrations of ammonia are an o rder of magnitude higher indoors than outdoors and appear to result in lowe r indoor acid panicle concentrations. Nitrous acid levels are higher indoor s than outdoors during both winter and summer and are substantially higher in homes with unvented combustion sources.