Indoor Air Quality, Information, and Socio-Economic Status: Evidence from Delhi

Michael Greenstone, Kenneth Lee, and Harshil Sahai

Key Findings:

• Researchers find that on average, indoor PM2.5 is substantially worse than the values reported by the government monitors and that this pattern holds in both low and high SES households (mean differences of +114.4µg/m3 and +122.3µg/m3, respectively).
• 24% (24.1%) of high SES households and only 2% (1.8%) of low SES households own an air purifier, but despite this difference, the indoor PM2.5 concentration is only 10 % less in high SES households as compared to low SES households.
• 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.)
• However, there was a significant increase in the air pollution awareness index4, suggesting that the information video and real-time information on PM2.5 levels increase awareness.
• Among high SES households, the study also spots a decline of 8.6% of PM2.5 levels in households that had real-time information for the same during the treatment period.
• Findings also indicate an increase in ventilation habits5 among these households, which might be linked to the decline noted above.