Personal exposure to particulate matter and heart rate variability among informal electronic waste workers at Agbogbloshie: a longitudinal study

Table 2 Variation in Heart rate variability among e-waste and non-e-waste worker

Variable	E-waste –workers (n = 142)	Comparable group (n = 65)	p-value
5-min resting Heart Rate Variability, Mean (SD)
RI (Dry season)
Mean NN	5.97 ± 0.31	6.35 ± 0.21	≤ 0.001
Log SDNN	4.23 ± 0.68	5.88 ± 0.08	≤ 0.001
Log RMSSD	4.88 ± 0.84	5.72 ± 0.30	≤ 0.001
Log LF	9.98 ± 1.98	11.12 ± 0.68	≤ 0.001
Log HF	9.25 ± 2.25	10.77 ± 0.91	≤ 0.001
LF/HF ratio	2.75 ± 2.33	1.84 ± 1.66	0.004
R II (Rainy season)
Mean NN	6.01 ± 0.29	6.24 ± 0.30	≤ 0.001
Log SDNN	5.28 ± 0.67	5.60 ± 0.55	≤ 0.001
Log RMSSD	4.85 ± 0.93	5.48 ± 0.74	≤ 0.001
Log LF	10.00 ± 2.07	10.71 ± 1.53	0.030
Log HF	9.19 ± 2.49	10.28 ± 1.83	0.010
LF/HF ratio	3.50 ± 5.12	1.85 ± 1.31	0.010
R III (Harmattan season)
Mean NN	5.89 ± 0.26	5.91 ± 0.84	0.841
Log SDNN (ms)	5.02 ± 0.82	5.34 ± 0.67	0.030
Log RMSSD (ms)	4.55 ± 0.94	5.05 ± 0.83	0.010
Log LF (ms²)	9.36 ± 2.38	10.22 ± 1.71	0.030
Log HF (m/s)	8.45 ± 2.57	9.57 ± 2.06	0.010
LF/HF ratio	3.60 ± 2.93	2.46 ± 1.81	0.010
Heart rate (beats/min), Mean (SD)
Round I	73.91 ± 10.16	74.09 ± 13.63	0.960
Round II	70.16 ± 10.64	69.52 ± 10.54	0.050
Round III	73.91 ± 10.16	74.00 ± 12.67	0.960

Sampling rounds were aligned to annual seasonal changes in study area, i.e. R I, II and III were aligned to the dry, rainy and harmattan respectively
Abbreviations: R round, Mean NN mean normal to normal beats, SDNN standard deviation of normal-to-normal, RMSSD; LF low frequency, HF high frequency, LF/HF ratio ratio of high frequency and low frequency
Bold p-values are significant at p ≤ 0.05

ISSN: 1471-2458