Is there a timelier solution to air pollution in today's cities?
Authors: Bin Zhao, Chen Chen, Bin Zhou
Journal: The Lancet Planetary Health (2018)

70 years have passed since the Great Smogs broke in two of the world's largest cities: Los Angeles, CA, USA, in 1942 and London, UK, in 1952. It had been decades before legislations—eg, the Clean Air Acts—were enforced, and air pollution levels were brought down. But the problem has never gone away. The latest WHO urban air quality database suggests that 98% of cities with more than 100 000 inhabitants in low-income and middle-income countries, and 56% of those in high-income countries, do not meet WHO air quality guidelines.1WHOWHO global urban ambient air pollution database (update 2016). World Health Organization, Geneva2016http://www.who.int/phe/health_topics/outdoorair/databases/cities/en/Date accessed: June 13, 2016Google Scholar As happened in Los Angeles and London, it is expected that air pollution will persist in these cities for decades to come. However, being in an era when technological advances have made fictions reality, can scientists and stakeholders find a timelier solution to these same old problems? We want to share one possibility. People spend the overwhelming majority of time indoors every day (up to 85–90% according to the US Environmental Protection Agency), which leaves a huge opportunity to reduce exposure to air pollution if a clean indoor environment can be provided. Air cleaners are an obvious candidate. These simple devices clean indoor air that people are mostly exposed to, with recent evidence supporting their health benefits.2Cosselman KE Navas-Acien A Kaufman JD Environmental factors in cardiovascular disease.Nat Rev Cardiol. 2015; 12: 627-642Crossref PubMed Scopus (311) Google Scholar, 3Chen R Zhao A Chen H et al.Cardiopulmonary benefits of reducing indoor particles of outdoor origin: a randomized, double-blind crossover trial of air purifiers.J Am Coll Cardiol. 2015; 65: 2279-2287Crossref PubMed Scopus (181) Google Scholar They are affordable too: an average low-power air cleaner with enough capacity to clean fine particles in a middle-sized living room costs only US$90 in China, according to our survey on China's major online-shopping sites. However, despite their effectiveness and affordability, less than 10% of Chinese families had air cleaners in 2015,4China Electronics News2015 China's air purifier industry report (in Chinese).http://jydq.cena.com.cn/2016-03/20/content_321705.htmDate accessed: June 13, 2016Google Scholar with even fewer using them regularly owing to a lack of awareness. This limited use of air cleaners results in a huge preventable proportion of morbidity and mortality due to air pollution in cities. Back in 1968, William Hildemann defended their proactive actions against air pollution despite the absence of conclusive scientific evidence on its health effects: "Twenty years from now we might have lots of hard evidence, but by that time it may be too late for hundreds of thousands of people."5Boffey PM Smog: Los Angeles running hard, standing still.Science. 1968; 161: 990-992Crossref PubMed Scopus (4) Google Scholar The same is to be said in today's situation: 20 years from now it might be possible to reduce air pollution to an acceptable level, but by then it could be too late for hundreds of millions of people. Well designed policies—eg, government subsidies—are needed to make sure that the benefits also reach the less privileged, but there is no excuse not to take immediate action when a feasible, timelier solution is readily at hand. We have received funding from the National Key Research and Development Program of China (2017YFC0702700) and funding from the Innovative Research Groups of the National Natural Science Foundation of China (51521005).