It Starts at the Beginning: Effect of Particulate Matter In Utero

Impact of prenatal and postnatal household air pollution exposure on lung function of 2-year old Nigerian children by oscillometry

RATIONALE

Lung function is adversely affected by exposure to household air pollution (HAP). Studies investigating the impact of prenatal and postnatal HAP exposure on early childhood lung development are limited, especially from Sub-Saharan Africa.

OBJECTIVE

We used oscillometry to investigate the impact on lung function of prenatal and postnatal HAP exposure of children born to Nigerian women who participated in a randomized controlled cookstove intervention trial.

METHODS

We performed oscillometric measurements (R: airway resistance; X: airway reactance; Fres: resonant frequency; AX: reactance area) in 223 children starting at age of 2 years (ethanol stove, n = 113; firewood/kerosene, n = 110). Personal exposure monitoring assessed mothers' prenatal exposure to particulate matter less than 2.5 μm in aerodynamic diameter (PM2.5). Postnatal HAP exposure was measured by determining household PM2.5 levels. We employed linear regression analysis to examine the association of prenatal and postnatal HAP exposures with children's lung function. Models were adjusted for age, gender, weight, height, group (intervention or control), birthweight and gestational age.

RESULTS

Mean age of the children was 2.9 years (standard deviation = 0.3); 120 were boys (53.8%) and 103 were girls (46.2%). Higher postnatal PM2.5 exposures were significantly associated with higher airway reactance at 5 Hz (X5 Hz; p = 0.04) in adjusted models. There were no significant associations between prenatal or postnatal PM2.5 exposure levels and other oscillometry parameters in adjusted regression analysis.

CONCLUSIONS

This is the first study to use oscillometry to explore the relationship between HAP exposure and lung function in children as young as 2 years. The findings provide some evidence that increased postnatal HAP exposure may result in poorer lung function in children, although larger studies are needed to confirm observed results. This study indicates that oscillometry is a low-cost and effective method to determine lung function in early childhood.

Data fusion for air quality mapping using low-cost sensor observations: Feasibility and added-value

In Nantes, low-cost sensors were installed in the city center and deployed on driving school cars, ambulances and service vehicles to measure PM₁₀ concentrations. This work aims to use the large amount of observations provided by the sensors for air quality mapping at the urban scale in order to show the potential added-value with respect to the dispersion model (ADMS-Urban) calculations. A preprocessing is applied to the raw sensor dataset to remove the unreliable observations based on an outlier detection technique and to compensate for the measurement drift by adjusting the estimated daily variation of the underlying background PM₁₀ concentrations with the reference stations. Then, data fusion is performed by combining the preprocessed fixed and mobile low-cost sensor observations and the 2016 annual average of the ADMS-Urban outputs. The measurement uncertainty related to the low-cost sensors and the dispersion of the data are considered in data fusion as the Variance of Measurement Error (VME). The spatial interpolation is achieved at hourly resolution and results are presented for November 29th, 2018 from 7 am to 7 pm. Hourly fused maps show disparate responses to data fusion mainly depending on the variability of the sensor data and the correlation between the sensor observations and the drift. The data fusion performance has been investigated by comparing the daily average of the estimated concentrations, the reference observations and the hourly model outputs at each station of the Air Pays de la Loire network. Results show that considering the model alone implies 8% bias whereas including the LCS observations reduces the bias to 2.5%. However, the concentration distributions related to the data fusion are characterized by a lower dispersion than the reference observations and the model estimation. Thus, the fusion smooths the PM₁₀ peaks. In addition, the effect of the measurement uncertainty has been investigated by doubling it or reducing it to the reference station measurement uncertainty. The sensitivity study demonstrates that the performance is increasing by reducing the uncertainty. This highlights the importance to estimate accurately the measurement uncertainty of the devices to ensure relevant air quality mapping. The method efficiency is also quite limited by the low correlation between the sensor observations and the model used as external drift in the kriging that may be explained by the remaining bias on LCS data. Efforts on this issue might increase the performance of the spatial interpolation.

Assessment of hair cell damage and developmental toxicity after fine particulate matter 2.5 μm (PM 2.5) exposure using zebrafish (Danio rerio) models

OBJECTIVES

Particulate matter (PM) exposure has become one of the most serious problems. The aim of the present study was to evaluate the hair cell damage and possible developmental toxicity caused by PM_2.5 exposure using a zebrafish model.

METHODS

Zebrafish embryos were exposed to various concentrations of PM_2.5. Developmental toxicity was evaluated based on general morphology score (GMS) system and Panzica-Kelly score, and by measurement of body length and heart rate. To evaluate hair cell damage, the average number of total hair cells within four neuromasts exposed to various concentrations of PM_2.5 was compared with that of the control group.

RESULTS

Morphological abnormalities evaluated by the GMS system and Panzica-Kelly score were rare and body length tended to be shorter in the PM_2.5-exposed groups. Heart rate decreased significantly in the PM_2.5-exposed group. Additionally, significant hair cell damage was observed after PM_2.5 exposure. It was dose-dependent and more severe after a longer period exposure (10 dpf).

CONCLUSIONS

In zebrafish embryos, exposure of PM_2.5 in the early stages of life decreased heart rate and caused significant hair cell damage in a dose-dependent manner.

Lung Development and Aging

The onset of chronic obstructive pulmonary disease (COPD) can arise either from failure to attain the normal spirometric plateau or from an accelerated decline in lung function. Despite reports from numerous big cohorts, no single adult life factor, including smoking, accounts for this accelerated decline. By contrast, five childhood risk factors (maternal and paternal asthma, maternal smoking, childhood asthma and respiratory infections) are strongly associated with an accelerated rate of lung function decline and COPD. Among adverse effects on lung development are transgenerational (grandmaternal smoking), antenatal (exposure to tobacco and pollution), and early childhood (exposure to tobacco and pollution including pesticides) factors. Antenatal adverse events can operate by causing structural changes in the developing lung, causing low birth weight and prematurity and altered immunological responses. Also important are mode of delivery, early microbiological exposures, and multiple early atopic sensitizations. Early bronchial hyperresponsiveness, before any evidence of airway inflammation, is associated with adverse respiratory outcomes. Overlapping cohort studies established that spirometry tracks from the preschool years to late middle age, and those with COPD in the sixth decade already had the worst spirometry at age 10 years. Alveolar development is now believed to continue throughout somatic growth and is adversely impacted by early tobacco smoke exposure. Genetic factors are also important, with genes important in lung development and early wheezing also being implicated in COPD. The inescapable conclusion is that the roots of COPD are in early life, and COPD is a disease of childhood adverse factors interacting with genetic factors.

Urban fine particulate matter exposure causes male reproductive injury through destroying blood-testis barrier (BTB) integrity

Blood-testis barrier (BTB) provides a suitable microenvironment for germ cells that is required for spermatogenesis. Exposure to particulate matter (PM) is recognized to occasion male reproductive impairment, but the mechanism of which remains unclear. Male Sprague-Dawley (SD) rats were used to establish animal models with PM_2.5 exposure concentration of 0, 10, and 20mg/kg.b.w. once a day for four weeks. Success rate of mating, sperm quality, epididymal morphology, expressions of spermatogenesis markers, superoxide dismutases (SOD) activity and expression in testicular tissues, and expressions of BTB junction proteins were detected. In addition, in vitro experiments were also performed. After PM_2.5 treatment, reactive oxygen species (ROS) production and apoptosis of Sertoli cells were analyzed. Our results indicated that after PM_2.5 exposure male rats presented inferior uberty and sperm quality, with decreased expressions of spermatogenesis markers, escalated SOD activity and expression levels, and reduced expressions of tight junction, adherens junction, and gap junction proteins in testicular tissues. Meantime, PM_2.5-treated Sertoli cells displayed increased SOD production and apoptosis. PM_2.5 exposure engenders male reproductive function injury through breaking BTB integrity.

Severe and Moderate Asthma Exacerbations in Asthmatic Children and Exposure to Ambient Air Pollutants

BACKGROUND

It is well established that short-term exposure to ambient air pollutants can exacerbate asthma, the role of early life or long-term exposure is less clear. We assessed the association between severe asthma exacerbations with both birth and annual exposure to outdoor air pollutants with a population-based cohort of asthmatic children in the province of Quebec (Canada).

METHOD

Exacerbations of asthma occurring between 1 April 1996 and 31 March 2011 were defined as one hospitalization or emergency room visit with a diagnosis of asthma for children (<13 years old) already diagnosed with asthma. Annual daily average concentrations of ozone (O₃) and nitrogen dioxide (NO₂) were estimated at the child's residential postal code. Satellite based levels of fine particulate (PM2.5) estimated for a grid of 10 km by 10 km were also assigned to postal codes of residence for the whole province. Hazard ratios (HRs) were estimated from Cox models with a gap time approach for both birth and time-dependant exposure.

RESULTS

Of the 162,752 asthmatic children followed (1,020,280 person-years), 35,229 had at least one asthma exacerbation. The HRs stratified by age groups and adjusted for the year of birth, the ordinal number of exacerbations, sex, as well as material and social deprivation, showed an interquartile range increase in the time-dependant exposure to NO₂ (4.95 ppb), O₃ (3.85 ppb), and PM2.5 (1.82 μg/m³) of 1.095 (95% CI 1.058-1.131), 1.052 (95% CI 1.037-1.066) and 1.025 (95% CI 1.017-1.031), respectively. While a positive association was found to PM2.5, no associations were found between exposure at birth to NO₂ or O₃.

CONCLUSIONS

Our results support the conclusion, within the limitation of this study, that asthma exacerbations in asthmatic children are mainly associated with time dependent residential exposures less with exposure at birth.