Indoor exposure to PM2.5, black carbon, and NO2 in New Orleans homes, and its effect on cardiovascular health.
The Household Air Pollution Study (HAPS) at Tulane University's Weatherhead School of Public Health measured indoor concentrations of PM2.5, black carbon, and nitrogen dioxide in homes across New Orleans.
Dr. Felicia Rabito's team placed monitors in participant homes to record exposure continuously, then compared pollutant levels with each participant's ambulatory blood pressure, respiratory function tests, and inflammatory biomarkers.
New Orleans is a useful place to study this. The housing is old, many homes cook with gas, the humid climate shapes how people ventilate, and several communities already carry a higher burden of cardiovascular disease.
I deployed and retrieved the PM2.5 and NO2 monitors in participant homes, coordinated with participants, followed the study's quality assurance protocols, and helped turn raw sensor output into datasets ready for analysis.
The work taught me how environmental measurements get tied to health outcomes in a real study.
Gas appliances, cooking, candles, tobacco and traffic outside the door each add to the air inside a home. Filter by pollutant to see where it comes from and which instrument measured it.
Schematic section of a New Orleans shotgun house. Select a source or monitor for details.
Illustrative schematic: source and monitor positions are representative, not a specific study home.
Fine particulate matter smaller than 2.5 micrometers in diameter. The particles reach deep into the lung alveoli and can enter the bloodstream, causing inflammation throughout the body. Indoor sources include cooking, candles, incense, and tobacco smoke.1
WHO guideline (2021)4
5µg/m³
annual mean
15µg/m³
24-hour mean
A component of soot from incomplete combustion of fossil fuels, biomass, and cooking fuels. In the study, each 1 µg/m³ increase in residential black carbon was associated with a 7.55 mmHg increase in systolic blood pressure.2
WHO guideline (2021)4
No guideline value. Evidence was judged insufficient to set one; WHO recommends measuring and reducing it.
Indoors, nitrogen dioxide comes mostly from gas stoves and space heaters. NO₂ irritates the airways, worsens asthma, and contributes to chronic respiratory disease. Poorly ventilated homes are hit hardest.3
WHO guideline (2021)4
10µg/m³
annual mean
25µg/m³
24-hour mean
WHO guideline values: WHO global air quality guidelines (2021), Table 0.1. 24-hour values are the 99th percentile, i.e. 3–4 exceedance days per year; the guidelines apply to indoor as well as outdoor air. For black carbon, WHO found the evidence insufficient to set a guideline level and issues good-practice statements instead.4
Per 1 µg/m³ of residential black carbon
+7.55mmHg
Systolic blood pressure increase
Each 1 µg/m³ increase in residential black carbon was associated with a 7.55 mmHg rise in systolic blood pressure.2 Across a whole population, a shift like this matters, especially in communities that already have high rates of cardiovascular disease.
What 2 mmHg means at population scale
A 2 mmHg population-level increase in systolic BP is associated with a 7% increase in ischemic heart disease mortality and a 10% increase in stroke mortality (Lewington et al., Lancet 2002; meta-analysis of one million adults in 61 prospective studies).5 These are population associations, not deaths estimated from this study.
Real-time PM2.5
Black carbon
Passive NO₂
24-hr blood pressure