There’s no safe level of air pollution and the health hazards tend to be greatest for vulnerable groups like pregnant women.
Research shows prolonged exposure to bushfire smoke increases the risk of pregnancy complications including high blood pressure, gestational diabetes, low birth weight and premature birth (before 37 weeks).
These conditions can have short-term and lifelong effects on a baby’s health, say researchers from the Robinson Research Institute at the University of Adelaide.
“Importantly in pregnant women, environmental pollutants can cause inflammatory damage to the placenta’s blood supply. This can interfere with the placenta’s development and function, which can in turn compromise the growth of the foetus.
“Many studies have linked poor air quality, particularly with high levels of PM2.5 (ultra-fine particles), to poor pregnancy outcomes. Data from 183 countries showed in 2010, an estimated 2.7 million premature births, 18 per cent of the total, were associated with PM2.5 pollution,” they wrote in The Conversation.
A 2019 study of more than 500,000 pregnant women from Colorado looked at the effect of bushfire smoke on pregnancy outcomes. The study found PM2.5 due to bushfire smoke was linked to spikes in premature birth, especially in women exposed during the second trimester.
For every 1 microgram/m³ increase in average daily exposure to PM2.5 during the second trimester of pregnancy, the risk of premature birth increased by 13 per cent.
To put this into context, in Canberra in the first week of January, PM2.5 levels averaged more than 200 micrograms/m³, compared with the typical background concentration of 5 micrograms/m³.