Geoffrey Morgan

Maternal exposure to particulate air pollution and term birth weight : a multi-country evaluation of effect and heterogeneity

Background: A growing body of evidence has associated maternal exposure to air pollution with adverse effects on fetal growth; however, the existing literature is inconsistent. Objectives: We aimed to quantify the association between maternal exposure to particulate air pollution and term birth weight and low birth weight (LBW) across 14 centers from 9 countries, and to explore the influence of site characteristics and exposure assessment methods on between-center heterogeneity in this association. Methods: Using a common analytical protocol, International Collaboration on Air Pollution and Pregnancy Outcomes (ICAPPO) centers generated effect estimates for term LBW and continuous birth weight associated with PM10 and PM2.5 (particulate matter ≤ 10 and 2.5 µm). We used meta-analysis to combine the estimates of effect across centers (~ 3 million births) and used meta-regression to evaluate the influence of center characteristics and exposure assessment methods on between-center heterogeneity in reported effect estimates. Results: In random-effects meta-analyses, term LBW was positively associated with a 10-μg/m3 increase in PM10 [odds ratio (OR) = 1.03; 95% CI: 1.01, 1.05] and PM2.5 (OR = 1.10; 95% CI: 1.03, 1.18) exposure during the entire pregnancy, adjusted for maternal socioeconomic status. A 10-μg/m3 increase in PM10 exposure was also negatively associated with term birth weight as a continuous outcome in the fully adjusted random-effects meta-analyses (–8.9 g; 95% CI: –13.2, –4.6 g). Meta-regressions revealed that centers with higher median PM2.5 levels and PM2.5:PM10 ratios, and centers that used a temporal exposure assessment (compared with spatiotemporal), tended to report stronger associations. Conclusion: Maternal exposure to particulate pollution was associated with LBW at term across study populations. We detected three site characteristics and aspects of exposure assessment methodology that appeared to contribute to the variation in associations reported by centers.

Air pollution and Hospital admissions in Sydney, Australia, 1990 to 1994

OBJECTIVES This study examined the effects of outdoor air pollutants on daily hospital admissions in Sydney, Australia. METHODS A time-series analysis of counts of daily hospital admissions and outdoor air pollutants (1990 to 1994) was performed, by means of Poisson regression that allowed for overdispersion and autocorrelation. RESULTS An increase in daily maximum 1-hour concentration of nitrogen dioxide from the 10th to the 90th percentile was associated with an increase of 5.29% (95% confidence interval = 1.07, 9.68) in childhood asthma admissions and 4.60%(-0.17,9.61) in chronic obstructive pulmonary disease (COPD) admissions. A similar increase in daily maximum 1-hour particulate concentration was associated with an increase of 3.01% (-0.38, 6.52) in COPD admissions. An increase from the 10th to the 90th percentile in daily maximum 1-hour nitrogen dioxide, daily maximum 1-hour ozone, and daily mean particulate was associated with an increase in heart disease admissions among those 65 years and older of 6.71% (4.25, 9.23), 2.45% (-0.37, 5.35), and 2.82% (0.90, 4.77), respectively. Heart disease and childhood asthma were primarily associated with nitrogen dioxide; COPD was associated with both nitrogen dioxide and particulates. CONCLUSIONS Current levels of air pollution in Sydney are associated with increased hospitalization for respiratory and heart disease.

Extreme air pollution events from bushfires and dust storms and their association with mortality in Sydney, Australia 1994–2007

INTRODUCTION Extreme air pollution events due to bushfire smoke and dust storms are expected to increase as a consequence of climate change, yet little has been published about their population health impacts. We examined the association between air pollution events and mortality in Sydney from 1997 to 2004. METHODS Events were defined as days for which the 24h city-wide concentration of PM(10) exceeded the 99th percentile. All events were researched and categorised as being caused by either smoke or dust. We used a time-stratified case-crossover design with conditional logistic regression modelling adjusted for influenza epidemics, same day and lagged temperature and humidity. Reported odds ratios (OR) and 95% confidence intervals are for mortality on event days compared with non-event days. The contribution of elevated average temperatures to mortality during smoke events was explored. RESULTS There were 52 event days, 48 attributable to bushfire smoke, six to dust and two affected by both. Smoke events were associated with a 5% increase in non-accidental mortality at a lag of 1 day OR (95% confidence interval (CI)) 1.05 (95%CI: 1.00-1.10). When same day temperature was removed from the model, additional same day associations were observed with non-accidental mortality OR 1.05 (95%CI: 1.00-1.09), and with cardiovascular mortality OR (95%CI) 1.10 (95%CI: 1.00-1.20). Dust events were associated with a 15% increase in non-accidental mortality at a lag of 3 days, OR (95%CI) 1.16 (95%CI: 1.03-1.30). CONCLUSIONS The magnitude and temporal patterns of association with mortality were different for smoke and dust events. Public health advisories during bushfire smoke pollution episodes should include advice about hot weather in addition to air pollution.

Effects of Bushfire Smoke on Daily Mortality and Hospital Admissions in Sydney, Australia

Background: Little research has investigated the health effects of particulate exposure from bushfires (also called wildfires, biomass fires, or vegetation fires), and these exposures are likely to increase, for several reasons. We investigated associations of daily mortality and hospital admissions with bushfire-derived particulates, compared with particulates from urban sources in Sydney, Australia from 1994 through 2002. Methods: On days with the highest particulate matter (PM)10 concentrations, we assumed PM10 was due primarily to bushfires. We calculated the contribution of bushfire PM10 on these days by subtracting the background PM10 concentration estimated from surrounding days. We assumed PM10 on the remaining days was from usual urban sources. We implemented a Poisson model, with a bootstrap-based methodology, to select optimum smoothed covariate functions, and we estimated the effects of bushfire PM10 and urban PM10, lagged up to 3 days. Results: We identified 32 days with extreme PM10 concentrations due to bushfires or vegetation-reduction burns. Although bushfire PM10 was consistently associated with respiratory hospital admissions, we found no consistent associations with cardiovascular admissions or with mortality. A 10 &mgr;g/m3 increase in bushfire PM10 was associated with a 1.24% (95% confidence interval = 0.22% to 2.27%) increase in all respiratory disease admissions (at lag 0), a 3.80% (1.40% to 6.26%) increase in chronic obstructive pulmonary disease admissions (at lag 2), and a 5.02% (1.77% to 8.37%) increase in adult asthma admissions (at lag 0). Urban PM10 was associated with all-cause and cardiovascular mortality, as well as with cardiovascular and respiratory hospital admission, and these associations were not influenced by days with extreme PM10 concentrations. Conclusions: PM10 from bushfires is associated primarily with respiratory morbidity, while PM10 from urban sources is associated with cardiorespiratory mortality and morbidity.

Impact of ambient air pollution on birth weight in Sydney, Australia

Background: Studies in Asia, Europe, and the Americas have provided evidence that ambient air pollution may have an adverse effect on birth weight, although results are not consistent. Methods: Average exposure during pregnancy to five common air pollutants was estimated for births in metropolitan Sydney between 1998 and 2000. The effects of pollutant exposure in the first, second, and third trimesters of pregnancy on risk of “small for gestational age” (SGA), and of pollutant exposure during pregnancy on birth weight were examined. Results: There were 138 056 singleton births in Sydney between 1998 and 2000; 9.7% of babies (13 402) were classified as SGA. Air pollution levels in Sydney were found to be quite low. In linear regression models carbon monoxide and nitrogen dioxide concentrations in the second and third trimesters had a statistically significant adverse effect on birth weight. For a 1 part per million increase in mean carbon monoxide levels a reduction of 7 (95% CI −5 to 19) to 29 (95% CI 7 to 51) grams in birth weight was estimated. For a 1 part per billion increase in mean nitrogen dioxide levels a reduction of 1 (95% CI 0 to 2) to 34 (95% CI 24 to 43) grams in birth weight was estimated. Particulate matter (diameter less than ten microns) in the second trimester had a small statistically significant adverse effect on birth weight. For a 1 microgram per cubic metre increase in mean particulate matter levels a reduction of 4 grams (95% CI 3 to 6) in birth weight was estimated. Conclusion: These findings of an association between carbon monoxide, nitrogen dioxide, and particulate matter, and reduction in birth weight should be corroborated by further study.

Ambient Air Pollution and Birth Defects in Brisbane, Australia

Background Birth defects are a major public health concern as they are the leading cause of neonatal and infant mortality. Observational studies have linked environmental pollution to adverse birth outcomes, including congenital anomalies. This study examined potential associations between ambient air pollution and congenital heart defects and cleft lip or palate among births in Brisbane, Australia (1998–2004). Methods Ambient air pollution levels were averaged over weeks 3–8 of pregnancy among 150,308 births. Using a case–control design, we used conditional logistic regression and matched cases to 5 controls. Analyses were conducted using all births, and then births where the mother resided within 6 and 12 kilometers of an ambient air quality monitor. Findings When analyzing all births there was no indication that ambient air pollution in Brisbane was associated with a higher risk of cardiac defects. Among births where the mother resided within 6 kilometers of an ambient air quality monitor, a 5 ppb increase in O3 was associated with an increased risk of pulmonary artery and valve defects (OR 2.96, 95% CI: 1.34, 7.52) while a 0.6 ppb increase in SO2 was associated with an increased risk of aortic artery and valve defects (OR 10.76, 95% CI: 1.50, 179.8). For oral cleft defects among all births, the only adverse association was between SO2 and cleft lip with or without cleft palate (OR 1.27, 95% CI: 1.01, 1.62). However, various significant inverse associations were also found between air pollutants and birth defects. Conclusions This study found mixed results and it is difficult to conclude whether ambient air pollution in Brisbane has an adverse association with the birth defects examined. Studies using more detailed estimates of air pollution exposure are needed.

Air pollution and daily mortality in Sydney, Australia, 1989 through 1993.

OBJECTIVES This study examined the effects of outdoor air pollutants in Sydney, Australia, on daily mortality. METHODS Time-series analysis was performed on counts of daily mortality and major outdoor air pollutants (particulates, ozone, and nitrogen dioxide) in Sydney (1989 to 1993) with adjustment for seasonal and cyclical factors. Poisson regression was calculated with allowance for overdispersion and autocorrelation. The effects of lagging exposure by 0 to 2 days were assessed with single- and multiple-pollutant models. RESULTS An increase in daily mean particulate concentration from the 10th to the 90th centile was associated with an increase of 2.63% (95% confidence interval 0.87 to 4.41) in all-cause mortality and 2.68% (0.25 to 5.16) in cardiovascular mortality. An increase in daily maximum 1-hour ozone concentration from the 10th to the 90th centile was associated with an increase of 2.04% (0.37 to 3.73) in all-cause mortality and 2.52% (-0.25 to 5.38) in cardiovascular mortality. An increase in the daily mean nitrogen dioxide concentration from the 10th to the 90th centile was associated with an increase of 7.71% (-0.34 to 16.40) in respiratory mortality. Multiple-pollutant models suggest that the effects of particulates and ozone on all-cause and cardiovascular mortality, and of nitrogen dioxide on respiratory mortality, are independent of the effects of the other pollutants. CONCLUSIONS Current levels of air pollution in Sydney are associated with daily mortality.

Evaluation of interventions to reduce air pollution from biomass smoke on mortality in Launceston, Australia: retrospective analysis of daily mortality, 1994-2007.

Objective To assess the effect of reductions in air pollution from biomass smoke on daily mortality. Design Age stratified time series analysis of daily mortality with Poisson regression models adjusted for the effects of temperature, humidity, day of week, respiratory epidemics, and secular mortality trends, applied to an intervention and control community. Setting Central Launceston, Australia, a town in which coordinated strategies were implemented to reduce pollution from wood smoke and central Hobart, a comparable city in which there were no specific air quality interventions. Participants 67 000 residents of central Launceston and 148 000 residents of central Hobart (at 2001 census). Interventions Community education campaigns, enforcement of environmental regulations, and a wood heater replacement programme to reduce ambient pollution from residential wood stoves started in the winter of 2001. Main outcome measures Changes in daily all cause, cardiovascular, and respiratory mortality during the 6.5 year periods before and after June 2001 in Launceston and Hobart. Results Mean daily wintertime concentration of PM10 (particulate matter with particle size <10 µm diameter) fell from 44 µg/m3 during 1994-2000 to 27 µg/m3 during 2001-07 in Launceston. The period of improved air quality was associated with small non-significant reductions in annual mortality. In males the observed reductions in annual mortality were larger and significant for all cause (−11.4%, 95% confidence interval −19.2% to −2.9%; P=0.01), cardiovascular (−17.9%, −30.6% to −2.8%; P=0.02), and respiratory (−22.8%, −40.6% to 0.3%; P=0.05) mortality. In wintertime reductions in cardiovascular (−19.6%, −36.3% to 1.5%; P=0.06) and respiratory (−27.9%, −49.5% to 3.1%; P=0.07) mortality were of borderline significance (males and females combined). There were no significant changes in mortality in the control city of Hobart. Conclusions Decreased air pollution from ambient biomass smoke was associated with reduced annual mortality in males and with reduced cardiovascular and respiratory mortality during winter months.

Impact of ambient air pollution on gestational age is modified by season in Sydney, Australia

BackgroundThe effect of individual pollutants and the period(s) during pregnancy when pollutant levels are likely to have most impact on preterm birth is not clear. We evaluated the effect of prenatal exposure to six common urban air pollutants in the Sydney metropolitan area on preterm birth.MethodsWe obtained information on all births in metropolitan Sydney between January 1, 1998 and December 31, 2000. For each birth, exposure to each air pollutant was estimated for the first trimester, the three months preceding birth, the first month after the estimated date of conception and the month prior to delivery. Gestational age was analysed as a categorical variable in logistic regression models.ResultsThere were 123 840 singleton births in Sydney in 1998–2000 and 4.9% were preterm. Preterm birth was significantly associated with maternal age, maternal smoking, male infant, indigenous status and first pregnancy. Air pollutant levels in the month and three months preceding birth had no significant effect on preterm birth after adjusting for maternal and infant covariates. Ozone levels in the first trimester of pregnancy and spring months of conception and sulphur dioxide were associated with increased risks for preterm births. Nitrogen dioxide was associated with a decreased risk of preterm births.ConclusionWe found more protective than harmful associations between ambient air pollutants and preterm births with most associations non-significant. In view of these inconsistent associations, it is important to interpret the harmful effects with caution. If our results are confirmed by future studies then it will be imperative to reduce Sydneys already low air pollution levels even further.

The reduction of rhinitis symptoms by nasal filters during natural exposure to ragweed and grass pollen

Background:  Prototype nasal filters were developed to collect inhaled pollen. This study evaluated the efficacy of the filters for prevention of rhinitis symptoms during acute outdoor pollen exposure.