Cooking Activities in the Absence of Combustion Heating Processes

Cooking on a stove (natural gas) can be classified as light or intensive. Light cooking activities were reported in dwelling A1 as cooking soup and making chai latte (Figure S10). During these two activities, the mean calculated PM2.5 concentration was approximately 40 μg/m3. The mean submicron PN concentration was approximately 1.4 <sup>×</sup> 105 cm−<sup>3</sup> and 1.6 <sup>×</sup> 105 cm−<sup>3</sup> during cooking soup and making chai latte, respectively. The corresponding calculated PM10 concentrations were approximately 144 μg/m<sup>3</sup> and 160 μg/m3 and the coarse PN concentrations were approximately 3 cm−<sup>3</sup> and 1 cm<sup>−</sup>3, respectively. Here, the differences in the PM10 and coarse PN concentrations were unlikely due to the cooking processes, but rather driven by occupancy and occupant movement-induced particle resuspension near the instruments, which was more intense during cooking soup.

Light cooking activities (such as making tea and/or coffee) were also reported in GFA2, which had a central heating system. During the making of tea and coffee, the mean calculated PM2.5 concentrations were approximately 16 μg/m<sup>3</sup> and 31 μg/m3, respectively (Figure S17). The mean submicron PN concentrations were approximately 1.2 <sup>×</sup> 105 cm−<sup>3</sup> and 4.6 <sup>×</sup> 104 cm<sup>−</sup>3, respectively. The corresponding calculated PM10 concentrations were approximately 52 μg/m<sup>3</sup> and 42 μg/m3, respectively, and the coarse PN concentrations were about 1 cm<sup>−</sup>3. This indicates that similar activities might have different impacts on particle concentrations depending on the indoor conditions and the way in which the activity was conducted. For example, variability in dwelling ventilation may play a role, as well as the burning intensity of the natural gas stove.

Intensive cooking activities were reported in dwelling GFA2 (Figure S17, central heating) and A2 (Figure S15, AC heating). Indoor aerosol concentrations during these intensive cooking activities were higher than those observed during light cooking activities (in the absence of combustion heating processes). For example, the mean calculated PM2.5 concentrations were between 62 μg/m<sup>3</sup> and 88 <sup>μ</sup>g/m3. The mean submicron PN concentrations were between 7.4 <sup>×</sup> 104 cm−<sup>3</sup> and 2.1 <sup>×</sup> 105 cm<sup>−</sup>3. The corresponding mean calculated PM10 concentrations were between 112 μg/m3 and 201 μg/m<sup>3</sup> and the mean coarse PN concentrations were between 3 cm−<sup>3</sup> and 14 cm<sup>−</sup>3.
