Air Pollution

The study by researchers at Lawson Health Research Institute; evidence of a strong association between exposure to sulfur dioxide during pregnancy and adverse birth outcomes. “This is the first study in Southwestern Ontario to investigate the association between air pollution and adverse outcomes; while also considering the other determinants of health; including socioeconomic, medical, psychosocial and behavioral-related factors that are also with birth outcomes,” explains Dr. Jason Gilliland.
The objective of the study was to test the relative influence of these factors on low birthweight and preterm birth in this region. The final sample consisted of over 25,000 live births at London Health Sciences Centre (LHSC) between February 2009 and February 2014.

Variables in the mode

Pregnant women in Southwestern Ontario 3.4 times more likely to have a low birthweight baby and two times more likely to have a preterm birth for every 1-parts per billion increase in sulfur dioxide; adjusting for all other variables in the model. This translates to a 30 % increase in low birthweight and a 20 % increase in preterm birth when comparing a typical high exposure to sulfur dioxide to a typical low exposure to sulfur dioxide.

Their findings are in keeping with other research; evidence is accumulating that toxic air travels through pregnant women’s lungs and are found in their placentas. “There is definitely a major concern for pregnant women who live in areas with high exposure to sulfur dioxide.”

About 67 % of sulfur dioxide emissions come from smelters and utilities; 25 % from other industrial sources. Sulfur dioxide is also present in motor vehicle emissions. The research team found that the best predictor of both adverse birth outcomes was previous preterm birth. Sulfur dioxide was the only physical environment variable highly with low birth weight and preterm birth.

The adverse birth outcomes

Their next step will identify geographical clusters or ‘hotspots’ of sulfur dioxide exposure and adverse birth outcomes in Southwestern Ontario. The identification of these clusters will provide knowledge on where health promotion interventions need to be focused in the future. While many factors contribute to a healthy pregnancy, the takeaway message is that the quality of airwomen breathe is also important.

If health care providers could informed of the hazards of air pollution to developing fetuses; they could make recommendations to pregnant patients about limiting exposure when air quality is poor.” Such recommendations could include more time spent indoors with windows closed, particularly during commuter rush hours, or taking other means to limit exposure when local air quality is poor.

This information could also incorporated when making public health warnings related to air quality. Other measures are sticking to indoor exercise when pollution levels are high and keeping windows when traveling by car. The study, “Geospatial analyses of adverse birth outcomes in Southwestern Ontario: examining the impact of environmental factors,” has published in Environmental Research.