Relationship between life-time exposure to ambient fine particulate matter and carotid artery intima-media thickness in Australian children aged 11-12 years

Increased vascular stiffness in children exposed in utero but not children exposed postnatally to emissions from a coal mine fire

Background

Chronic, low-intensity air pollution exposure has been consistently associated with increased atherosclerosis in adults. However, there was limited research regarding the implications of acute, high-intensity air pollution exposure during childhood. We aimed to determine whether there were any associations between early-life exposure to such an episode and early-life vascular function changes.

Methods

We conducted a prospective cohort study of children (<9 years old) who lived in the vicinity of the Hazelwood coal mine fire (n = 206). Vascular function was measured using noninvasive diagnostic methods including carotid intima-media thickness and pulse wave velocity (PWV). Exposure estimates were calculated from prognostic models and location diaries during the exposure period completed by each participant's parent. Linear mixed-effects models were used to determine whether there were any associations between exposure and changes in vascular outcomes at the 3- and 7-year follow-ups and over time.

Results

At the 7-year follow-up, each 10 μg/m3 increase in daily PM2.5 in utero was associated with increased PWV (β = 0.13 m/s; 95% confidence interval [CI] = 0.02, 0.24; P = 0.02). The association between in utero exposure to daily PM2.5 was not altered by adjustment for covariates, body mass index, and maternal fire stress. Each 1 µg/m3 increase in background PM2.5 was associated with increased PWV (β = 0.68 m/s; 95% CI = 0.10, 1.26; P = 0.025), in children from the in utero exposure group. There was a trend toward smaller PWV (β = -0.17 m/s; 95% CI = -0.366, 0.02) from the 3- to 7-year follow-up clinic suggesting that the deficits observed previously in children exposed postnatally did not persist.

Conclusion

There was a moderate improvement in vascular stiffness of children exposed to PM2.5 from a local coal mine fire in infancy. There was a mild increase in vascular stiffness in children exposed to PM2.5 from a local coal mine fire while their mothers were pregnant.

Associations of time-weighted individual exposure to ambient particulate matter with carotid atherosclerosis in Beijing, China

BACKGROUND

Time-location information (time spent on commuting, indoors and outdoors around residential and work places and physical activity) and infiltrated outdoor pollution was less considered estimating individual exposure to ambient air pollution. Studies investigating the association between individual exposure to particulate matter (PM) with aerodynamic diameter < 10 μm (PM₁₀) and < 2.5 μm (PM_2.5) and carotid atherosclerosis presented inconsistent results. Moreover, combined effect of pollutants on carotid atherosclerosis was not fully explored. We aimed to investigate the association between long-term individual time-weighted average exposure to PM_2.5 and PM₁₀ and the risk of carotid atherosclerosis, and further explore the overall effect of co-exposure to pollutants on carotid atherosclerosis.

METHODS

The study population included 3069 participants derived from the Beijing Health Management Cohort (BHMC) study. Daily concentration of ambient air pollutants was estimated by land-use regression model at both residential and work addresses, and one- and two-year time-weighted average individual exposure was calculated by further considering personal activity pattern and infiltration of ambient air pollution indoors. We explored the association of PM_2.5 and PM₁₀ with carotid atherosclerosis and pooled the overall effect of co-exposure to ambient air pollutants by quantile g-computation.

RESULTS

A significant association between time-weighted average exposure to PM_2.5 and PM₁₀ and carotid atherosclerosis was observed. Per interquartile range increase in two-year exposure to PM_2.5 (Hazard ratio (HR): 1.322, 95% confidence interval (CI): 1.219-1.434) and PM₁₀ (HR:1.213, 95% CI: 1.116-1.319) showed the strongest association with carotid atherosclerosis, respectively. Individuals in higher quartiles of pollutants were at higher risk for carotid atherosclerosis compared with those in the lowest quartile group. Concentration response functions documented the nearly linear and nonlinear relationship and interpreted the upward trends of the risk for carotid atherosclerosis with increasing level of pollutant concentrations. Moreover, effect estimates for the mixture of pollutants and carotid atherosclerosis were larger than any of the individual pollutants (HR (95% CI) was 1.510 (1.338-1.704) and 1.613 (1.428-1.822) per quartile increase for one-year and two-year time-weighted average exposure, respectively).

CONCLUSIONS

Individual time-weighted average exposure to PM_2.5 and PM₁₀ was associated with carotid atherosclerosis. Co-exposure to ambient air pollution was also positively associated with carotid atherosclerosis.

Urban Fine Particulate Matter and Elements Associated with Subclinical Atherosclerosis in Adolescents and Young Adults

The relationships between the elemental constituents of PM_2.5 and atherosclerosis remain limited, especially in young populations. This study included 755 subjects aged 12-30 years in the Taipei metropolis. A land use regression model was used to estimate residential annual mean concentrations of PM_2.5 and eight elemental constituents. We evaluated the percent differences in carotid intima-media thickness (CIMT) with PM_2.5 and elemental constituent exposures by linear regressions. Interquartile range increments for PM_2.5 (4.5 μg/m³), sulfur (108.6 ng/m³), manganese (2.0 ng/m³), iron (34.5 ng/m³), copper (3.6 ng/m³), and zinc (20.7 ng/m³) were found to associate with 0.92% (95% confidence interval (CI): 0.17-1.66), 0.51% (0.02-1.00), 0.36% (0.05-0.67), 0.98% (0.15-1.82), 0.74% (0.01-1.48), and 1.20% (0.33-2.08) higher CIMTs, respectively. Factor analysis identified four air pollution source-related factors, and the factors interpreted as traffic and industry sources were associated with higher CIMTs. Stratified analyses showed the estimates were more evident in subjects who were ≥18 years old, females, or who had lower household income. Our study results provide new insight into the impacts of source-specific air pollution, and future research on source-specific air pollution effects in young populations, especially in vulnerable subpopulations, is warranted.

Ambient air pollution is associated with vascular disease in Ugandan HIV-positive adolescents

OBJECTIVE

In this study, we aim to investigate the relationship between particulate matter, a common proxy indicator for air pollution, and markers of inflammation, monocyte activation, and subclinical vascular disease.

DESIGN

A cross-sectional study.

METHODS

Adolescents with perinatally acquired HIV (PHIV) and HIV-uninfected adolescents between 10 and 18years living near Kampala, Uganda were included. Daily ambient concentrations of particulate matter (PM2.5) were measured from the Eastern Arica GEOHealth Hub. Outcome variables measured were carotid intima-media thickness (IMT), as well as plasma markers of systemic inflammation, oxidized lipids, and gut integrity. Multivariable quantile regression models were used to explore the relationship between PM2.5 and IMT.

RESULTS

One hundred and nineteen participants (69 PHIV, 50 HIV-uninfected) were included. The median (Q1, Q3) age was 12.7 (11.4,14.2) years, 55% were girls. Median daily PM2.5 exposure was 29.08 μg/m3 (23.40, 41.70). There was no significant difference in exposure of PM2.5 between groups (P  = 0.073). PM2.5 significantly correlated with intestinal permeability (zonulin; r = 0.43, P < 0.001), monocyte activation (soluble CD163: r  = 0.25, P = 0.053), and IMT (r  = 0.35, P = 0.004) in PHIV but not in HIV-uninfected (P ≥ 0.05). In multivariable quantile regression, after adjusting for age, sex, poverty level, soluble CD163, and zonulin, daily PM2.5 concentrations remained associated with IMT [β  = 0.005, 95% CI (0.0003-0.010), P = 0.037] in adolescents with PHIV.

CONCLUSION

Adolescents in urban Uganda are exposed to high levels of air pollution. Both PM2.5 and HIV have independently been observed to contribute to atherosclerotic disease, and our findings suggest the combined effects of HIV and air pollution may amplify the development of cardiovascular disease.