In 1905, the Public Health Congress convened in London, where Dr. Henry Antoine des Voeux presented a paper entitled “Fog and Smoke.” In it, he described the characteristic black smoky fog – or “smog” – that enveloped London and many of the world’s other urban centers. Credited with coining this new term, Dr. des Voeux introduced a word that over the next century would become synonymous with the traffic congestion of the sprawling Los Angeles metropolitan area.
Driven by increasing recognition of the adverse health effects of air pollution (and perhaps a dislike of the dubious distinction of being home to America’s most polluted region), California instituted aggressive pollution-reduction strategies. Many of these policies have been successful, and over the past few decades, air pollution levels have been decreasing. But do these improvements in air quality lead to important, measurable benefits for people living in southern California?
A new study published in NEJM suggests they do, demonstrating an association between decreasing pollution and improving lung function growth in children. The study included cohorts of children in five communities, from three separate time periods enrolled as part of the 20-year Children’s Health Study. The enrolled children were near 11 years of age at the start, and the cohorts were each followed with longitudinal lung function tests for four years (1994-1998, 1997-2001, and 2007-2011), as this is the period when the lungs grow substantially in size. The investigators examined the association between levels of nitrogen dioxide, particulate matter, and ozone and children’s lung function growth during the same period.
The results: for nitrogen dioxide, every decrease of 14.1 parts per billion was associated with a 91.4mL increase in the mean four-year growth of FEV1 (P<0.001). There were similar improvements in FVC. This association was also demonstrated for particulate matter, but not for ozone. Significant improvements were observed for boys and girls and for children with and without asthma. The authors conclude that these data suggest “that all children have the potential to benefit from improvements in air quality.”
A separate analysis revealed that the proportion of 15-year-old children with low FEV1 (that is, <80% predicted) declined over the study period as air quality improved: 7.9% in first cohort, 6.3% in the second and 3.6% in the most recent (P < 0.005).
Editor-in-Chief Dr. Jeffrey Drazen notes that “while an observational study alone cannot determine causation, these data are compelling and add to an important body of evidence suggesting that incremental improvements in pollution have important clinical benefits.”
In an accompanying editorial, Douglas Dockery and James Ware of the Harvard School of Public Health agree, writing, “Some have argued that the substantial improvements in air quality over the past 40 years are sufficient to protect public health…However, the current report and other studies suggest that further improvement in air quality may have beneficial public health effects.” This study, then, is good news, but there may still be work left to do to protect our children’s lungs from the smoky fog.
Also, watch the Quick Take video summary of these research results.