Delhi is one of the most polluted cities across the globe. During recent years, with the air quality routinely reaching hazardous levels during the winter season1, there has been increased focus and demand for action regarding ambient air quality. This has created momentum among government agencies to form policies and design interventions to address the issue. However, indoor air quality (IAQ) has not received any such attention. Information is a key determinant in the demand for clean air, which in turn, can drive the introduction and implementation of public policies that can address air pollution. Indoor air quality monitors (IAQMs), which measure and communicate real-time levels of indoor PM2.5 and other pollutants—can potentially address any market failures related to awareness and information.
In this study, researchers first look at the comparison between indoor and outdoor quality, establishing the need for awareness. Next, they look at behavioral changes and participants’ demand for clean air after being exposed to air quality information of the household.

To understand the indoor-outdoor air quality researchers look at two sections of populations in the city, divided based on their socio economic status (SES), and compare the indoor PM2.5 levels with the corresponding ambient levels. The study takes into account ~ 300 low SES households mostly consisted of poor, non-migrant individuals living in Delhi2. 1248 medium and high SES households were sampled from 90 neighborhood clusters across the city. Additionally, researchers also assessed the effect of information on high SES households and the subsequent demand for clean air through investments in defensive mechanisms over the month. A small section of high SES households was also provided wifi-enabled IAQ monitoring devices, which allowed the researchers to collect minute-wise IAQ information for the
treatment period (4 weeks). Using geotagged locations, researchers matched these data points with the corresponding ambient air quality collected via the nearest government-installed monitor.
By combining data collected using both air quality monitors with survey data collected at the beginning and end of the study period, researchers investigated the effect of different levels of air quality information on participants’ knowledge of air quality, changes in their behavior, demand for clean air and the eventual change in their indoor air quality.

Relative to the ambient air, indoor PM2.5 rise more quickly in the morning and evening hours, at periods where the household is likely to be cooking. There is a substantial degree of spatial variation in PM2.5, evidenced by the wide variation in PM2.5 levels captured by Delhi’s government monitors at any given point in time. The user trial did not result in higher investments in defensive mechanisms against indoor air pollution (like the purchase of air purifiers, door seal gaps, etc.)

In this study, researchers found that indoor air pollution levels are 20 times higher than WHO standards, regardless of socio-economic strata. Despite these levels, the study observes relatively low ownership of air purifiers (4.9 percent in the medium and high SES household sample), suggesting that the demand for defensive technologies may be modest. The experiment results suggest that a month-long experience with an indoor air quality monitor may not lead to investments in air purifiers. The findings suggest that the high-frequency IAP information provided by an IAQM does not fully address the information gaps about air pollution that may exist in this setting. Providing households with more substantial information about the health impacts of air pollution, for instance, may lead to different outcomes and is an area that deserves further study.

Learn more about the findings: Research Highlights