Characterization of indoor particle sources: A study conducted in the metropolitan Boston area

Pm intensive particle monitoring study was conducted in homes in the Boston , Massachusetts, area during the winter and summer of 1996 in an effort to characterize sources of indoor particles. As part of this study, continuous particle size and mass concentration data were collected in four single-fa mily homes, with each home monitored for one or two 6-day periods. Addition ally, housing activity and air exchange rate data were collected. Cooking, cleaning, and the movement of people were identified as the most important indoor particle sources in these homes. These sources contributed significa ntly both to indoor concentrations (indoor-outdoor ratios varied between 2 and 33) and to altered indoor particle size distributions. Cooking, includi ng broiling/baking, toasting, and barbecuing contributed primarily to parti culate matter with physical diameters between 0.02 and 0.5 mu m [PM(0.02-0. 5)], with volume median diameters of between 0.13 and 0.25 mu m. Sources of particulate matter with aerodynamic diameters between 0.7 and 10 pm [PM(0. 7-10)] included sauteing, cleaning (vacuuming, dusting, and sweeping), and movement of people, with volume median diameters of between 3 and 4.3 mu m Frying was associated with particles from both PM(0.02-0.5) and PM(0.7-10). Air exchange rates ranged between 0.12 and 24.3 exchanges/hr and had signi ficant impact on indoor particle levels and size distributions. Low air exc hange rates (< 1 exchange/hr) resulted in longer air residence times and mo re time for particle concentrations from indoor sources to increase. When a ir exchange rates were higher (> 1 exchange/hr), the impact of indoor sourc es was less pronounced, as indoor particle concentrations tracked outdoor l evels more closely.