TABLE 1.

Heart rate variability, exposure to 10 µg/m³ at rest, difference from baseline^a

ECG parameter/ exposure	During exposure	Hours after exposure				ANOVA
		0	3.5	15	21
RR (msec)
Air	20 ± 42	169 ± 34	–4 ± 25	80 ± 48	–34 ± 39	NS
UFP	16 ± 40	140 ± 31	–37 ± 45	71 ± 28	0.6 ± 21
SDNN (msec)
Air	29 ± 12	16 ± 17	–7 ± 8	0 ± 9	–6 ± 11	NS
UFP	35 ± 13	26 ± 8	13 ± 12	2 ± 17	33 ± 12
rMSSD (msec)
Air	19 ± 15	20 ± 21	–10 ± 9	8 ± 10	–13 ± 11	UFP × time: p = 0.032
UFP	31 ± 19	27 ± 9	2 ± 11	9 ± 22	25 ± 12
Low frequency (Hz)
Air	1411 ± 707	1213 ± 1435	–401 ± 511	366 ± 529	–228 ± 791	NS
UFP	1692 ± 449	693 ± 336	508 ± 321	458 ± 635	833 ± 482
High frequency (Hz)
Air	2022 ± 1706	672 ± 1665	–917 ± 680	686 ± 537	–1188 ± 925	NS
UFP	2566 ± 1459	1315 ± 696	44 ± 779	1022 ± 1655	2407 ± 1261
Low frequency/high frequency
Air	0.68 ± 0.45	–0.46 ± 0.29	0.15 ± 0.25	0.12 ± 0.59	0.42 ± 0.42	NS
UFP	0.30 ± 0.23	–0.28 ± 0.24	0.31 ± 0.58	0.10 ± 0.31	–0.03 ± 0.17

^aData are means ± SE.