Impacts of coal mine fire-related PM2.5 on the utilisation of ambulance and hospital services for mental health conditions

Climate change and an increase in the number of major fire events occurring around the world have drawn attention to the importance of understanding the association between air pollution events and mental health. In 2014, the Morwell open-cut brown coal mine adjacent to the Hazelwood power station in the Latrobe Valley region of Victoria, Australia, caught fire as a result of nearby wildfires, and exposed the local community to a prolonged period of deteriorated air quality. The aim of this study was to examine how exposure to coal mine fire-related fine particulate matter (PM2.5) during the event affected the utilisation of local health services for mental health conditions (ambulance attendances; emergency department (ED) presentations; hospital admissions). A time-series analysis indicated that mine fire-related PM2.5 exposure was associated with short-term increases in ambulance attendances and ED presentations but not hospital admissions. To allow for delays between exposure and changes in service utilisation, different lag periods were assessed. The most prominent effects were observed over a 5-day lag period where, for each 10µg/m3 increase in daily mean mine fire-related PM2.5, the risk of an ambulance attendance for anxiety increased by 34% (95%CI: 8% to 67%) and the risk of an ED presentation for depression increased by 36% (95%CI: 3% to 79%). Accordingly, ambulance and hospital services should expect to encounter an increase in the number of people seeking assistance for mental health conditions during extreme air pollution events and mechanisms need to be in place to ensure that surges in demand for mental health care during these circumstances can be accommodated.

68Maternal exposure to PM2.5 from a severe smoke event and birth outcomes in Victoria, Australia

Background The 2014 Hazelwood coal mine fire was an unprecedented six-week severe smoke event in the Latrobe Valley, southeastern Australia. We aimed to determine whether maternal exposure to fine particulate matter (PM2.5) attributable to the event was associated with adverse fetal growth or maturity, including birthweight, small for gestational age, term low birthweight or preterm birth. Methods A cohort of babies born within the affected region was defined used administrative perinatal data. Maternal average and peak PM2.5 was assigned to residential address at time of delivery using a chemical transport model. Maternal, infant, meteorological and temporal variables were included in final linear and log-binomial regression models. Results 3,591 singleton livebirths were included; 763 were exposed in utero. Average PM2.5 exposure was 4.4 µg/m3 (IQR 2.1 µg/m3); average peak was 45.0 µg/m3 (IQR 35.1 µg/m3). No association between PM2.5 and fetal growth or maturity was observed. Gestational diabetes mellitus was an effect modifier in the relationship; babies of exposed gestational diabetic mothers were 97 grams heavier per 10 µg/m3 increase in average PM2.5 exposure (95%CI 74, 120 grams), compared to mothers without gestational diabetes. Conclusions Maternal PM2.5 exposure from a smoke event was not associated with adverse fetal growth or maturity. There was a trophic response amongst babies of mothers with gestational diabetes. Key messages Babies born to mothers with gestational diabetes may be more susceptible to the effects of smoke events on birthweight.

67Maternal Exposure to PM2.5 from a Coal Mine Fire is Associated with Gestational Diabetes Mellitus

Background In 2014, the Hazelwood coal mine fire was an unprecedented six-week severe smoke event in the Latrobe Valley, southeastern Australia. We aimed to determine whether maternal exposure to fine particulate matter (PM2.5) attributable to coal mine fire smoke was associated with gestational diabetes mellitus (GDM), hypertensive disorders of pregnancy and abnormal placentation. Methods We defined a cohort of all births >20 weeks in the Latrobe Valley from 1 March 2012 - 31 Dec 2015 utilising administrative perinatal data. Average and peak PM2.5 was assigned to residential address at delivery using a chemical transport model. Maternal, meteorological and temporal variables were included in final log-binomial regression models. Results 3,612 singleton pregnancies were included; 766 were exposed to the smoke event. Average maternal PM2.5 exposure was 4.4 µg/m3 (IQR 2.1). Average peak PM2.5 exposure was 44.9 µg/m3 (IQR 35.0). An interquartile range increase in average and peak PM2.5 was associated with a 7% and 16% increased likelihood of GDM respectively (Average PM2.5 95%CI 1.03, 1.10; <0.0001; Peak PM2.5 95%CI 1.09, 1.22; <0.0001). No association for hypertensive disorders or abnormal placentation was observed. Conclusions This is the first study to examine obstetric complications relating to a discrete smoke event. These findings may guide the public health response to future similar events. Key messages Exposure to a smoke event was associated with an increased risk of GDM. The public health implications may be substantial with a changing climate.

Markers of Cardiovascular Disease among Adults Exposed to Smoke from the Hazelwood Coal Mine Fire

Little research has examined the effects of high concentration, medium-duration smoke exposure on cardiovascular health. We investigated whether six weeks of exposure to smoke from the 2014 Hazelwood coal mine fire in Victoria (Australia), was associated with long-term clinical or subclinical cardiovascular disease approximately four years later, in adult residents of the towns of Morwell (exposed, n = 336) and Sale (unexposed, n = 162). The primary outcome was serum high sensitivity (hs) C-reactive protein (CRP). Blood pressure, electrocardiogram, flow mediated dilatation and serum levels of hs-troponin, N-terminal pro B-type natriuretic peptide and lipids were secondary outcomes. There was no significant difference in weighted median hsCRP levels between exposed and unexposed participants (1.9 mg/L vs. 1.6 mg/L, p = 0.273). Other outcomes were comparable between the groups. hsCRP was associated in a predictable manner with current smoking, obesity and use of lipid-lowering therapy. Four years after a 6-week coal mine fire, this study found no association between smoke exposure and markers of clinical or subclinical cardiovascular disease in exposed adults.

Sub-Clinical Effects of Outdoor Smoke in Affected Communities

Many Australians are intermittently exposed to landscape fire smoke from wildfires or planned (prescribed) burns. This study aimed to investigate effects of outdoor smoke from planned burns, wildfires and a coal mine fire by assessing biomarkers of inflammation in an exposed and predominantly older population. Participants were recruited from three communities in south-eastern Australia. Concentrations of fine particulate matter (PM2.5) were continuously measured within these communities, with participants performing a range of health measures during and without a smoke event. Changes in biomarkers were examined in response to PM2.5 concentrations from outdoor smoke. Increased levels of FeNO (fractional exhaled nitric oxide) (β = 0.500 [95%CI 0.192 to 0.808] p < 0.001) at a 4 h lag were associated with a 10 µg/m3 increase in PM2.5 levels from outdoor smoke, with effects also shown for wildfire smoke at 4, 12, 24 and 48-h lag periods and coal mine fire smoke at a 4 h lag. Total white cell (β = −0.088 [−0.171 to −0.006] p = 0.036) and neutrophil counts (β = −0.077 [−0.144 to −0.010] p = 0.024) declined in response to a 10 µg/m3 increase in PM2.5. However, exposure to outdoor smoke resulting from wildfires, planned burns and a coal mine fire was not found to affect other blood biomarkers.