UV Study
VCH Hygiene
23 December, 2025
November 4th UV on
n = 3
n = 3
November 12th UV on
November 18th UV off
n = 3
n = 3
NWCA bacteria breathing zone sample 3 = TNTC
November 25th UV Off
n = 3
n = 3
UV On & Off Comparison West Wing
Statistical Analysis
West Wing Vent Height - Bacteria
##
## Shapiro-Wilk normality test
##
## data: filtered_data$concentration
## W = 0.65568, p-value = 2.372e-09##
## Shapiro-Wilk normality test
##
## data: filtered_data$log_concentration
## W = 0.98066, p-value = 0.6065The log-transformed concentrations are approximately normal.
##
## Welch Two Sample t-test
##
## data: log_concentration by uv
## t = -1.9496, df = 44.978, p-value = 0.05747
## alternative hypothesis: true difference in means between group off and group on is not equal to 0
## 95 percent confidence interval:
## -0.94106269 0.01531909
## sample estimates:
## mean in group off mean in group on
## 3.617556 4.080428No statistically significant reduction in concentration was observed between UV off and on.
## # A tibble: 2 × 3
## uv mean_concentration median_concentration
## <chr> <dbl> <dbl>
## 1 off 48.5 30
## 2 on 85.4 55## [1] -75.96567The bacterial concentration with UV on was ~76% higher than with UV off.
West Wing Vent Height - Fungi
##
## Shapiro-Wilk normality test
##
## data: filtered_data$concentration
## W = 0.61215, p-value = 5.005e-10##
## Shapiro-Wilk normality test
##
## data: filtered_data$log_concentration
## W = 0.96963, p-value = 0.245The log-transformed concentrations are approximately normal.
##
## Welch Two Sample t-test
##
## data: log_concentration by uv
## t = -3.5531, df = 45.994, p-value = 0.0008929
## alternative hypothesis: true difference in means between group off and group on is not equal to 0
## 95 percent confidence interval:
## -1.4036904 -0.3884282
## sample estimates:
## mean in group off mean in group on
## 2.376771 3.272830UV on concentrations were significantly higher than UV off
## # A tibble: 2 × 3
## uv mean_concentration median_concentration
## <chr> <dbl> <dbl>
## 1 off 14.6 10
## 2 on 39.0 25## [1] -167.1429The fungal concentration with UV on was ~167% higher than with UV off.
West Wing Breathing Zone - Bacteria
##
## Shapiro-Wilk normality test
##
## data: filtered_data$concentration
## W = 0.59535, p-value = 3.716e-10##
## Shapiro-Wilk normality test
##
## data: filtered_data$log_concentration
## W = 0.97143, p-value = 0.3001The log-transformed concentrations are approximately normal.
##
## Welch Two Sample t-test
##
## data: log_concentration by uv
## t = -2.575, df = 44.707, p-value = 0.01341
## alternative hypothesis: true difference in means between group off and group on is not equal to 0
## 95 percent confidence interval:
## -0.9848439 -0.1202842
## sample estimates:
## mean in group off mean in group on
## 3.623586 4.176151Bacterial concentrations were significantly higher with UV on than UV off.
## # A tibble: 2 × 3
## uv mean_concentration median_concentration
## <chr> <dbl> <dbl>
## 1 off 45 40
## 2 on 89.4 65## [1] -98.61111The bacterial concentration with UV on was ~99% higher than with UV off.
West Wing Breathing Zone - Fungi
##
## Shapiro-Wilk normality test
##
## data: filtered_data$concentration
## W = 0.90471, p-value = 0.0008952##
## Shapiro-Wilk normality test
##
## data: filtered_data$log_concentration
## W = 0.94772, p-value = 0.03247##
## Wilcoxon rank sum test with continuity correction
##
## data: concentration by uv
## W = 111.5, p-value = 0.0002323
## alternative hypothesis: true location shift is not equal to 0##
## Welch Two Sample t-test
##
## data: log_concentration by uv
## t = -4.0882, df = 44.217, p-value = 0.0001807
## alternative hypothesis: true difference in means between group off and group on is not equal to 0
## 95 percent confidence interval:
## -0.9621385 -0.3268140
## sample estimates:
## mean in group off mean in group on
## 2.581490 3.225966Both parametric (Welch t-test on natural log-transformed data, p = 0.00018) and non-parametric (Wilcoxon rank-sum test, p = 0.00023) analyses confirmed a significant increase in bacterial concentrations with UV on.
## # A tibble: 2 × 3
## uv mean_concentration median_concentration
## <chr> <dbl> <dbl>
## 1 off 15.2 15
## 2 on 28.1 25## [1] -84.93151The fungal concentration with UV on was ~85% higher than with UV off.
Nov 12 East & West Wing Vent Height - Bacteria
##
## Shapiro-Wilk normality test
##
## data: filtered_data$concentration
## W = 0.92994, p-value = 0.2723##
## Shapiro-Wilk normality test
##
## data: filtered_data$log_concentration
## W = 0.86964, p-value = 0.03333Normality assumptions not met.
##
## Wilcoxon rank sum test with continuity correction
##
## data: concentration by uv
## W = 9, p-value = 0.0383
## alternative hypothesis: true location shift is not equal to 0There was a statistically significant difference in bacterial concentration between UV on and UV off.
## # A tibble: 2 × 3
## uv mean_concentration median_concentration
## <chr> <dbl> <dbl>
## 1 off 32.5 20
## 2 on 78.9 75## [1] -142.735The bacterial concentration with UV on was ~143% higher than with UV off.
Nov 12 East & West Wing Vent Height - Fungi
##
## Shapiro-Wilk normality test
##
## data: filtered_data$concentration
## W = 0.75514, p-value = 0.001033##
## Shapiro-Wilk normality test
##
## data: filtered_data$log_concentration
## W = 0.98816, p-value = 0.9982The log-transformed data are consistent with a normal distribution.
##
## Welch Two Sample t-test
##
## data: log_concentration by uv
## t = -0.49069, df = 12.989, p-value = 0.6318
## alternative hypothesis: true difference in means between group off and group on is not equal to 0
## 95 percent confidence interval:
## -1.2690904 0.7993246
## sample estimates:
## mean in group off mean in group on
## 3.359825 3.594708##
## Wilcoxon rank sum test with continuity correction
##
## data: concentration by uv
## W = 23.5, p-value = 0.723
## alternative hypothesis: true location shift is not equal to 0There is no statistically significant difference between UV off and UV on.
## # A tibble: 2 × 3
## uv mean_concentration median_concentration
## <chr> <dbl> <dbl>
## 1 off 35.8 25
## 2 on 60 40## [1] -67.44186The fungal concentration with UV on was ~67% higher than with UV off.
Nov 12 East & West Wing Breathing Zone - Bacteria
##
## Shapiro-Wilk normality test
##
## data: filtered_data$concentration
## W = 0.95072, p-value = 0.5359##
## Shapiro-Wilk normality test
##
## data: filtered_data$log_concentration
## W = 0.87225, p-value = 0.03642Normality assumptions not met.
##
## Wilcoxon rank sum test with continuity correction
##
## data: concentration by uv
## W = 10, p-value = 0.05099
## alternative hypothesis: true location shift is not equal to 0There is no statistically significant difference between UV off and UV on.
## # A tibble: 2 × 3
## uv mean_concentration median_concentration
## <chr> <dbl> <dbl>
## 1 off 34.2 32.5
## 2 on 67.2 70## [1] -96.74797The bacterial concentration with UV on was ~97% higher than with UV off.
Nov 12 East & West Wing Breathing Zone - Fungi
##
## Shapiro-Wilk normality test
##
## data: filtered_data$concentration
## W = 0.84697, p-value = 0.01574##
## Shapiro-Wilk normality test
##
## data: filtered_data$log_concentration
## W = 0.95893, p-value = 0.6738##
## Wilcoxon rank sum test with continuity correction
##
## data: concentration by uv
## W = 26, p-value = 0.952
## alternative hypothesis: true location shift is not equal to 0##
## Welch Two Sample t-test
##
## data: log_concentration by uv
## t = 0.0066502, df = 6.4187, p-value = 0.9949
## alternative hypothesis: true difference in means between group off and group on is not equal to 0
## 95 percent confidence interval:
## -0.9295146 0.9346614
## sample estimates:
## mean in group off mean in group on
## 3.474321 3.471748There is no statistically significant difference between UV off and UV on.
## # A tibble: 2 × 3
## uv mean_concentration median_concentration
## <chr> <dbl> <dbl>
## 1 off 44.2 27.5
## 2 on 34.4 35## [1] 22.01258The fungal concentration with UV on was ~22% lower than with UV off.