Air quality improvements may yield huge gains in health
Even small risk reductions achieved with improved air quality afford health benefits similar to that gained with smoking and systolic hypertension control, according to a study in an urban China population.
Importantly, more health benefits could be gained with more aggressive reductions in fine particulate matter (PM2.5) levels, the authors said. “Our results suggest that air quality improvement should be among the highest priority goals for preventing noncommunicable disease [NCD] deaths and disability in China.”
In the study, the authors conducted a computer simulation experiment to investigate the potential cardiovascular (CV) and non-CV health benefits of achieving three air quality targets by 2030: Beijing Olympic Games level (mean PM2.5, 55 μg/m3), China Class II standard (35 μg/m3) or World Health Organization (WHO) standard (10 μg/m3).
Resulting data indicated that reducing the mean PM2.5 to Beijing Olympic levels by 2030 was projected to yield around 241,000 life-years annually. Even greater life gains could be had if the China Class II or WHO PM2.5 standard would be met (annual average, 992,000 and 1,576,000 life years, respectively). [Circulation 2017;136:1575-1584]
Of note, the health benefits gained with reaching either the last two air quality targets would appear to be greater than that achieved with the combined WHO-recommended goals of 25-percent improvement in systolic hypertension control and 30-percent reduction in smoking (928,000 life-years annually).
“Traditional NCD risk factors [such as blood pressure and smoking] convey a higher magnitude of individual risk than air pollution, but these risk factors affect only segments of the population,” the authors noted.
In contrast, while air pollution risk is marginal at the individual level, the entire population is exposed to poor air quality, “so that our projected health benefits from more aggressive air pollution control policies were comparable in magnitude with control of 30 percent active smoking or 25 percent of systolic hypertension,” they explained.
According to simulation data, gradually improving air quality to WHO recommended PM2.5 concentration would translate to an estimated reduction of 0.6 million annual total deaths on average over 2017 to 2030 among adults aged 35 to 84 years in urban China alone.
“Thus, substantial reduction in disease burden can be achieved for entire populations by controlling air pollution mainly via legislation, government policy and joint initiatives at the national level,” the authors said. Joint efforts may include the development of green transportation, reduction of industrial emission and implementation of governmental control measures.
However, in a linked commentary, Drs Griffith A. Bell and Michael Brauer pointed out that reaching the WHO-recommended PM2.5 limits in China would require dramatic efforts. “But large-scale air pollution control efforts in other countries have shown that large reductions not only are possible but also can be cost-effective.” [Circulation 2017;136:1585-1587]
“If the assumptions made by [the simulation study] are true, reducing PM2.5 to WHO-recommended levels could prevent millions of CV deaths in urban China by 2030,” according to Bell and Brauer, who also noted that the health benefits to improving air quality extend beyond CV disease.
Even so, as the study authors themselves acknowledged, the simulation model was specifically designed for CV disease. This underestimates the pulmonary disease burden averted by improved air quality.
“As China’s per capita income continues to rise and China continues its transition from an industrial to a service-based economy, demand for environmental progress will likely increase, as it has in countries that have made similar transitions,” Bell and Brauer said.
“Indeed, air pollution in several major Chinese cities has decreased in recent years despite increasing population and urbanization. Accelerating these efforts will be important to reducing the considerable health burden caused by air pollution in China,” they added.