The Air Purifier Paradox in South Asia: Underused Despite Suffocating Air Quality
In the first week of June 2023, New York City (NYC) faced an unprecedented level of air pollution. The harmful PM2.5 particle levels reached a record high of 117 micrograms per cubic meter (μg/m^3) on June 7th, due to smoke from wildfires in Quebec, Canada. This level not only shattered the city's previous record of 86 μg/m^3 but was also three times higher than the guideline of 35 μg/m^3 set by the US Environmental Protection Agency (EPA) and over eight times higher than the World Health Organization (WHO) guideline of 15 μg/m^3. While this event was extraordinary for NYC, such pollution levels are a daily reality for over 350 cities around the world, mainly in developing countries (Kelly, 2023). In fact, in cities across Bangladesh, India, and Pakistan, daily average PM2.5 levels surpassing the NYC record of 117 μg/m^3 are almost a routine occurrence.
Air pollution remains a leading cause of mortality, responsible for 9 million premature deaths annually, which equates to roughly 16% of all deaths worldwide, along with a staggering 268 million disability-adjusted life-years (Landrigan et al., 2018). The issue is particularly severe in South Asia, where air pollution causes an estimated 2 million deaths per year. Moreover, the per capita death rate from air pollution in South Asia has increased by 21% in the last decade, whereas it has decreased by 25% in high-income countries (IHME, 2020; The World Bank, 2023). Beyond its impact on public health, air pollution also significantly affects worker productivity (Graff Zivin & Neidell, 2012; Adhvaryu, Kala, and Nyshadham, 2022).
For decades, weak regulatory institutions and inconsistent enforcement of environmental laws have allowed high levels of pollution to persist in South Asia (Greenstone and Hanna, 2014). In this context, the importance of private defensive investments, such as air purifiers in households and workplaces, cannot be overstated.
Early findings from two field experiments (randomized control trials) in Dhaka, Bangladesh offer insights into the effectiveness of air purifiers. Preliminary results indicate that factories equipped with air purifiers between April and June 2023 saw a 37% reduction in indoor air pollution, with indoor PM2.5 concentrations measuring 25 µg/m^3 lower than those in environments without air purifiers (68 µg/m^3) (Garg, Jagnani, and Lozano-Garcia, 2023). Remarkably, workers in firms with air purifiers produced, on average, 27% more output than those in firms without air purifiers, despite indoor pollution levels remaining above the WHO's recommended limits. A cost-effectiveness analysis revealed that the average firm-level gains in productivity amounted to $5,710, yielding a benefit-cost ratio of 8.15 within just one month. Yet, firms in Bangladesh have not adopted air purifiers more widely, possibly due to financial constraints, lack of information, and other related factors.
In a pilot study involving households between December 2022 and March 2023, the provision of an air purifier reduced indoor air pollution levels by 27%, translating to a PM2.5 reduction of 74 μg/m^3 (Chowdhury et al., 2024). Importantly, owning an air purifier did not guarantee regular use; only about half of the households used their air purifiers for more than two hours a day on average, despite air pollution levels being 15 times higher than the WHO recommendation at 279 μg/m^3. The low cost of electricity for running air purifiers—approximately half the cost of a ceiling fan—suggests that financial considerations are unlikely to be the primary factor behind their underuse. This points to the influence of non-monetary factors on usage patterns.
Overall, further investigation into private strategies for combating air pollution is essential, especially in developing regions like South Asia. There is a critical need to evaluate the effectiveness, cost-efficiency, and usage of interventions such as air purifiers in homes and workplaces. Understanding these elements is crucial for guiding policies, business decisions, and individual actions in areas plagued by regulatory shortcomings or limited state capacity. Additionally, identifying the factors that motivate people and organizations to adopt and consistently use air purifiers is key to enhancing their deployment and efficacy in polluted environments.
Maulik Jagnani is an Assistant Professor of Economics at The Fletcher School, Tufts University.