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Field
Trial Title
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Before
Improving Residential Indoor Air Quality in Mexico City: Effects on Wellbeing and Productivity
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After
The Adoption and Impact of Air Purifiers: Evidence from a Field Experiment in Mexico City
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Field
Abstract
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Before
Air pollution has significant negative effects on health and economic outcomes in urban centers of Latin America and unequal exposure to air pollution may be exacerbating income and health inequalities. Because individuals spend most of their lives indoors, we will study residential indoor air quality in Mexico City. First, we will measure residential indoor air quality, including levels of particulate matter, and estimate the pass-through from outdoor air quality to indoor air quality. Second, we will use a randomized controlled trial and data from household surveys to address the following two research questions: (1) What barriers do households face in improving indoor air quality and what interventions are cost-effective in improving indoor air quality? (2) What is the effect of improved indoor air quality on households’ time use, economic
outcomes, such as productivity, and self-reported as well as objective measures of health and wellbeing, such as sleep quality?
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After
According to the World Health Organization, air pollution—both ambient and residential-- is the top environmental risk to health. Accordingly, air pollution is a growing topic of study. However, the bulk of the literature is focused on two disparate issues, outdoor air quality in cities and residential air quality related to cookstoves in rural areas. In contrast, very few studies focus on residential air quality in cities of the developing world. Yet, indoor air quality, and especially residential air quality, is likely to be critical for individuals’ outcomes, as people spend 60% of their time indoors. For example, residential air quality could affect sleep duration and quality, which in turn could affect health, wellbeing, and performance. Because outdoor air pollution levels are often higher in poor neighborhoods than in rich neighborhoods and pollutants, such as particulate matter, better permeate older and poorly constructed dwellings, residential air quality may exacerbate health and economic inequalities. Documenting the extent, determinants, and effects of air quality in urban homes in Mexico City will provide an understanding of the scale of the problem. Evidence on the barriers to improving residential air quality and the policy interventions that can overcome them is key to mitigating the impacts of pollution and addressing poverty for millions of households in fast-developing and highly polluted cities of countries like Mexico, India, and China.
This project addresses the following research questions:
1. What is the level of air pollution in a home in a below median income neighborhood in highly polluted city of a middle-income country?
2. What barriers prevent adoption of mitigating technology (air purifiers) among households in a below median income neighborhood in this context and what policies can overcome them?
3. What are the health and wellbeing effects of improved residential air quality for households in a below median income neighborhood in this context?
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Trial Start Date
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Before
October 16, 2023
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After
February 16, 2026
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Field
Trial End Date
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Before
December 31, 2026
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After
August 31, 2027
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Last Published
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Before
October 04, 2023 05:04 PM
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After
February 03, 2026 01:42 PM
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Intervention Start Date
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Before
October 16, 2023
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After
February 16, 2026
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Intervention End Date
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Before
February 16, 2024
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After
November 30, 2026
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Primary Outcomes (End Points)
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Before
Residential air quality as measured by air quality monitors installed by the study team.
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After
- Air quality: Hourly PM 2.5 at the household level.
- Sleep quality: Standardized index at the participant-day level.
- Wellbeing: Standardized index at the participant level as measured at endline.
- Willingness-to-pay: Incentivized stated price at the participant level as measured at endline.
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Field
Experimental Design (Public)
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Before
- Control group: Air quality monitoring only.
- T1: Air quality monitoring + Provision of information + Free air purifier.
- T2: Air quality monitoring + Provision of information + Free purifier set in automatic mode.
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After
Households will be randomized into one of the following three mutually exclusive intervention groups prior to baseline:
• 10-day Trial (200 households): Households will receive an offer for a free 10-day purifier trial (T-10).
• 90-day Trial (200 households): Households will receive an offer for a 90-day purifier trial (T-90).
• Control (C) (200 households): Households will not receive the purifier.
In addition, at endline, we will cross-randomize households into one of three information treatments:
• General Info (200 households): Households will receive information on how purifiers improved air quality and sleep during our pilot in Mexico City.
• Personalized Info (200 households): Households will receive information on how purifiers improved air quality and sleep among households with similar observable characteristics to theirs during our pilot.
• Control (C) (200 households): Households will not receive additional information.
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Randomization Method
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Before
Randomization on the spot through Survey CTO.
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After
Prior to the baseline survey, we will randomize the order of enrolled households into the three intervention treatment groups, generating a list for each enumerator (e.g., a sequence of T10, C, C, T90, T90, T10, ....) that enumerators will follow as they recruit households. In addition, prior to endline, we will cross-randomize households into one of three information treatments.
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Planned Number of Clusters
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Before
56 households for pilot study.
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After
600 households for full study.
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Planned Number of Observations
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Before
56 households for pilot.
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After
600 households for full study.
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Sample size (or number of clusters) by treatment arms
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Before
Control: 28 HHs.
T1: 14 HHs.
T2: 14 HHS.
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After
Control: 200 HHs (roughly 1/3 no info, 1/3 general info, 1/3 personalized)
T10: 200 HHs (roughly 1/3 no info, 1/3 general info, 1/3 personalized)
T90: 200 HHS (roughly 1/3 no info, 1/3 general info, 1/3 personalized)
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Secondary Outcomes (End Points)
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Before
o Purifier Data: purifier usage, as measured by smart outlets, to monitor whether behavior interferes with the effectiveness of the purifier
o Survey Data: time use (such as, exercising, studying, working, household chores, sleeping etc.), income, hours worked, self-reported physical health and mental health, cognition as measured by cognitive reflection questions/surveys/time diaries, beliefs and expectations about outdoor and indoor air quality and its effects.
o Wearables Data: Sleep quality, heart rate, breathing rate
o Health devices: Blood pressure and spirometers data.
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After
- Attrition: share of days with usable wearable data and endline responses for primary outcomes
- Physical health, as measured by index pf self-reports and metrics provided by the wearables (resting heart rate, daily heart rate variability in healthy range)
- Health behaviors: number of steps and time spent in sedentary activities (wearables)
- Self-reported sleep quality index
- Self-reported index of awareness of air quality issues and measures to reduce exposure
- Behavior: ventilation, smoking, and cooking habits as measured by self-reports as well as CO2
- Purifier usage
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