Table 3.

Noise exposure and the risk of IHD: summary of findings.

Noise Source	Outcome $	Number of Study Design (s) *	RR † per 10 dB (95% CI)	Participants (Cases)	Quality of Evidence ‡
Air traffic	Prev	2 CS	1.07 (0.94–1.23)	14,098 (340)	$\oplus$
	Inc	2 ECO	1.09 (1.04–1.15)	9,619,082 (158,977)	$\oplus$
	Mort	2 ECO	1.04 (0.97–1.12)	3,897,645 (26,066)	$\oplus$
		1 CO	1.04 (0.98–1.11)	4,580,311(15,532)	$\oplus \oplus$
Road traffic	Prev	8 CS	1.24 (1.08–1.42)	25,682 (1614)	$\oplus \oplus$
	Inc	1 ECO	1.12 (0.85–1.48)	262,830 (418)	$\oplus$
		3 CO, 4CC	1.08 (1.01–1.15)	67,224 (7033)	$\oplus \oplus \oplus \oplus$
	Mort	1 CC, 2 CO	1.05 (0.97–1.13)	532,268 (6884)	$\oplus \oplus \oplus$
Rail traffic	Prev	4 CS	1.18 (0.82–1.68)	13,241 (283)	$\oplus$

^$ Outcome: Prev = prevalence of IHD, Inc = incidence of IHD, Mort = mortality due to IHD; * ECO = ecological study, CS = cross-sectional study, CC = case-control study, CO = cohort study; ^†: RR = Relative Risk per 10 decibel (dB change in noise level, 95% CI = 95% Confidence Interval. For air, road –and, rail traffic, noise levels are expressed in L_DEN.; ^‡ GRADE Working Group Grades of Evidence: High quality (⊕⊕⊕⊕): Further research is very unlikely to change our confidence in the estimate of effect, Moderate Quality (⊕⊕⊕): Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate, Low Quality (⊕⊕): Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate, Very low quality (⊕): We are very uncertain about the estimate.