Fig. 4.
Association of short-term exposure to black carbon or elemental carbon (black circles) and particulate matter < 2.5 μm in diameter (open circles) with frequency domain measures of heart rate variability per interquartile range increase in mean (or median) pollutant concentration (in μg/m3). Studies are organized by endpoint (LF, HF, LFHFR), population type (i.e., healthy, pre-existing disease, older adults) and averaging time. Circles represent point estimates and horizontal lines represent 95% confidence intervals. BC = black carbon; CAD = coronary artery disease; COPD = chronic obstructive pulmonary disease; CVD = cardiovascular disease; d = day; EC = elemental carbon; h = hour; HF = high frequency; IQR = interquartile range; LF = low frequency; LFHFR = low frequency high frequency ratio; MA = moving average.