Health effects of indoor air pollution in Guatemala
by Catherine LaineMarch 20th, 2007
Photo by Debbie Coleman
This past Friday (March 16) I went to see John McCracken’s thesis defense at Harvard School of Public Health entitled “Respiratory & Cardio Effects of Household Biomass Smoke in Guatemala”. John’s work was part of the RESPIRE intervention trial that took place in the Guatemalan Highlands from 2002-2004. RESPIRE stands for Randomized Exposure Study of Pollution Indoors and Respiratory Effects. The primary purpose of the randomized control trial was to investigate the impact of decreasing indoor air pollution (through the use of improved woodstoves or planchas) on the incidence of acute lower respiratory tract infections in children in a rural developing country setting. Secondary goals included looking at the association between exposure to indoor air pollution (IAP) and blood pressure.
A WHO assessment found IAP to be the 8th most important risk factor for disease. It is a particularly important risk factor, as you might imagine, for acute respiratory tract infections (ARI) including bronchitis and pneumonia.Each year, IAP is implicated in the deaths of 1.6 million people. Because women and children spend the most time near the domestic hearth, they are especially vulnerable. In Guatemala as in many developing countries, mothers carry their children around on their backs during the first year of life. Unfortunately, this gives the tiny tots a hefty dose of indoor smoke when they are most susceptible to respiratory infections.
The study population for McCracken’s work included 534 households with either a pregnant woman or a child less that 4 months of age that used an open wood fire for cooking and heating. Pilot work done in the trial showed that the planchas were popular, durable, and improved the indoor air quality of the kitchen.
John discussed three of his papers during his defense, I’m going to focus on just two.
Paper Topic: Biomass Smoke Exposure and Acute Respiratory Infections
In this study 500 children were followed until 8 mos of age. Each week a fieldworker visited their homes and looked for a broad range of symptoms (cough, rapid breathing, chest indrawing) suggestive of respiratory infection. If the kiddies had symptoms, they were referred to the hospital in San Marcos where an MD did a more complete checkup.
Long story short: The use of a clean burning stove in the home resulted in a 25% reduction in the rate of acute respiratory tract infections. For you epi geeks, the adjusted rate ratio for MD defined ALRI was 0.74 (95% CI: 0.58-0.95). Note: 30% of the kids referred to the MD for ALRI didn’t go to the hospital for on reason or another.
Important factoid alert: Upper and lower respiratory tract infections are rather different (tend to be caused by different pathogens). Upper tract infections are about 10 times more common.
Paper Topic: Biomass Smoke Exposure and Blood pressure
In this study, 49 women had been randomly assigned to get the intervention (a new stove) and 71 were in the control group. After the end of that phase of the study, 55 of the controls were given new stoves as well. (I believe that the remaining 16 controls dropped out of the study).
Long story short: Use of planchas, which reduce/eliminate indoor air pollution, resulted in sizeable (and statistically significant) decrease in blood pressure (both diastolic and systolic). Why is this important? High blood pressure is associated with many cardiovascular diseases such as hypertension and heart disease.
Read the scientific paper.
Over the course of the trial, around 30 children died despite the high level of follow-up and attention, indicating the overall poor health status of the community.
Related Work
For more info, check out the work of Kirk Smith at Berkeley.
Indoor Air Pollution
The RESPIRE Trial is followed up by the CRECER (Chronic Respiratory Effects of Early Childhood Exposure to Respirable Particulate Matter) trial. Gotta love those acronyms.
Ezzati, M and, D. Kammen. 2001. Indoor air pollution from biomass combustion and acute respiratory infections in Kenya: an exposure-response study. Lancet, 358: 619-624. [pdf]
FYI: D. Kaemmen is Daniel Kammen of RAEL at UC Berkeley.
December 16th, 2009 at 5:22 am
Air pollution is made up of many kinds of gases, droplets and particles that reduce the quality of the air. Air can be polluted in both the city and the country. In the city, cars, buses and airplanes, as well as industry and construction may cause air pollution. Air pollution is a major environmental risk to health and is estimated to cause approximately 2 million premature deaths worldwide per year. Exposure to air pollutants is largely beyond the control of individuals and requires action by public authorities at the national, regional and even international levels.