Table 3:
Summary of 24-hour indoor fine particulate matter concentrations and infiltration efficiency across subcategories of 20 households in Western Montana, June through October 2022
| Indoor PM2.5 (μg/m3) | Infiltration efficiency (95% CI) | |||
|---|---|---|---|---|
| Sampling Days | mean (sd) min, P25, median, P75, max | Estimatea (95% CI) | ||
| All study days/households | 1860 | 5.6 (8.7) 1.0, 1.3, 2.5, 5.5, 117.7 |
0.34 (0.33, 0.35) |
|
| Non-Wildfire period | 1567 | 3.6 (5.2) 1.0, 1.1, 2.1, 3.9, 55.3 |
Reference | 0.39 (0.37, 0.42) |
| Wildfire period | 293 | 15.9 (14.7) 1.0, 5.6, 10.4, 21.0, 117.7 |
358.3 (311.4, 410.6) |
0.32 (0.28, 0.36) |
| Participant age <43 years (median) | 707 | 5.7 (8.9) 1.0, 1.4, 2.7, 5.9, 117.7 |
Reference | 0.33 (0.31, 0.35) |
| Participant age 43+ years (median) | 867 | 5.6 (9.3) 1.0, 1.2, 2.2, 4.8, 68.7 |
−11.2 (−20.0, −1.5) |
0.36 (0.34, 0.38) |
| Household income <$75,000 / year | 715 | 7.2 (11.0) 1.0, 1.6, 3.0, 7.3, 117.7 |
Reference | 0.52 (0.49, 0.54) |
| Household income $75,000+ / year | 1040 | 4.8 (7.1) 1.0, 1.2, 2.4, 5.1, 68.7 |
−26.8 (−33.6, −19.2) |
0.24 (0.23, 0.26) |
| Education bachelor’s or less | 989 | 5.5 (9.1) 1.0, 1.3, 2.5, 5.3, 117.7 |
Reference | 0.41 (0.39, 0.43) |
| Education advanced degree | 871 | 5.7 (8.3) 1.0, 1.3, 2.5, 5.7, 68.7 |
4.4 (−4.9, 14.7) |
0.27 (0.25, 0.29) |
| Home built before 1975 (median) | 902 | 6.8 (9.8) 1.0, 1.8, 3.3, 6.9, 117.7 |
Reference | 0.41 (0.39, 0.43) |
| Home built 1975 (median) or later | 958 | 4.4 (7.4) 1.0, 1.1, 1.9, 4.2, 62.9 |
−36.9 (−42.4, −30.9) |
0.27 (0.26, 0.29) |
| Home area <167 sqm (median) | 941 | 6.2 (9.6) 1.0, 1.5, 2.8, 5.9, 117.7 |
Reference | 0.43 (0.41, 0.45) |
| Home area 167+ sqm (median) | 824 | 5.3 (8.0) 1.0, 1.3, 2.5, 5.2, 68.7 |
−12.3 (−20.3, −3.5) |
0.26 (0.24, 0.29) |
| Home <10 windows (median) | 854 | 6.1 (9.6) 1.0, 1.4, 2.7, 5.8, 117.7 |
Reference | 0.39 (0.37, 0.41) |
| Home 10+ windows (median) | 1006 | 5.2 (7.9) 1.0, 1.2, 2.4, 5.1, 68.7 |
−12.7 (−20.5, −4.1) |
0.29 (0.27, 0.31) |
| Home <3 doors | 696 | 6.0 (9.4) 1.0, 1.3, 2.6, 6.0, 117.7 |
Reference | 0.36 (0.33, 0.38) |
| Home 3+ doors | 1164 | 5.3 (8.3) 1.0, 1.3, 2.5, 5.1, 68.7 |
−8.0 (−16.5, 1.3) |
0.33 (0.31, 0.35) |
| No pets in home | 631 | 5.0 (8.1) 1.0, 1.0, 2.0, 4.6, 55.3 |
Reference | 0.24 (0.22, 0.27) |
| 1+ pets in home | 1229 | 5.9 (9.1) 1.0, 1.4, 2.8, 5.9, 117.7 |
27.6 (15.7, 40.7) |
0.39 (0.37, 0.40) |
| Central AC in home | 504 | 5.2 (9.3) 1.0, 1.1, 1.9, 4.0, 62.9 |
Reference | 0.32 (0.29, 0.35) |
| No Central AC in home | 1356 | 5.7 (8.5) 1.0, 1.4, 2.8, 5.9, 117.7 |
27.8 (15.1, 41.9) |
0.35 (0.34, 0.37) |
| Any type of AC unit | 1155 | 5.1 (8.9) 1.0, 1.1, 2.2, 4.6, 117.7 |
Reference | 0.30 (0.28, 0.32) |
| No AC unit of any kind | 705 | 6.4 (8.5) 1.0, 1.7, 3.2, 6.9, 68.7 |
41.9 (29.0, 56.0) |
0.42 (0.40, 0.45) |
| No wood stove or fireplace in home | 1593 | 5.5 (8.8) 1.0, 1.2, 2.4, 5.2, 117.7 |
Reference | 0.33 (0.31, 0.34) |
| Wood stove or fireplace in home | 267 | 6.1 (8.3) 1.0, 1.7, 3.6, 6.7, 68.7 |
25.1 (9.5, 42.9) |
0.43 (0.40, 0.46) |
| No gas stovetop in home | 1331 | 5.2 (8.1) 1.0, 1.3, 2.5, 5.3, 117.7 |
Reference | 0.33 (0.31, 0.34) |
| Gas stovetop in home | 529 | 6.4 (10.2) 1.0, 1.1, 2.5, 5.8, 68.7 |
3.1 (−7.1, 14.3) |
0.37 (0.34, 0.40) |
| Portable air cleaner in home | 1312 | 5.1 (7.4) 1.0, 1.3, 2.5, 5.3, 68.7 |
Reference | 0.25 (0.24, 0.26) |
| No portable air cleaner in home | 548 | 6.7 (11.3) 1.0, 1.4, 2.5, 5.9, 117.7 |
9.8 (−0.9, 21.6) |
0.57 (0.54, 0.60) |
| Outdoor mean daily temperatureb <24 C | 932 | 7.1 (10.8) 1.0, 1.4, 3.0, 7.9, 117.7 |
Reference | 0.32 (0.30, 0.33) |
| Outdoor mean daily temperatureb 24+ C | 910 | 4.0 (5.6) 1.0, 1.2, 2.2, 4.2, 47.5 |
−30.1 (−36.3, −23.3) |
0.40 (0.37, 0.42) |
PM2.5 = fine particulate matter; sqm = square meters; sd = standard deviation; min = minimum; P25 = 25th percentile; P75 = 75th percentile; max = maximum; CI = confidence interval; C = degrees Celsius
a
Estimates are from simple linear regression analyses with 24-hour mean PM2.5 as the outcome and household/demographic characteristics as predictor variables. Estimates are presented as percent difference in geometric mean PM2.5.
b
Outdoor temperature categorized by median daily outdoor temperature measured by PurpleAir sensors over the duration of the study (24 C).