Assessing and Mitigating CO Intoxication Risk in Ciudad Juárez, México: An Interdisciplinary Approach by Patrick Gurian, Teresa Montoya, Zuber Mulla, Analila Rojo, Verónica Corella-Barud, and Gilberto Velázquez-Angulo July 26, 2005

Background In the last 12 years in Ciudad Juárez In the last 12 years in Ciudad Juárez –1,381 intoxicated by CO –167 deaths by CO Associated with un- vented heaters Associated with un- vented heaters Little systematic study in U.S.-México border region Little systematic study in U.S.-México border region

Objectives Develop strategy to mitigate health risks Develop strategy to mitigate health risks Conduct multiple small studies Conduct multiple small studies –Need a breadth of information from hazard identification to risk management strategies –Resources are limited –Proceed with best available information

Research Efforts 1.Retrospective analysis of reported intoxication cases Identify common risk factors Identify common risk factors 2. Monitor CO levels at 64 households Collect more detailed data on CO levels, usage patterns, heater type, etc. Collect more detailed data on CO levels, usage patterns, heater type, etc. 3. Develop promising risk communication strategy Must be effective-will reduce CO exposure Must be effective-will reduce CO exposure Realistic-will be implemented by subject population Realistic-will be implemented by subject population

Case-series study Case reports obtained for winter season Case reports obtained for winter season –Information on cause, date, time, location Summarized common factors Summarized common factors

Baseline data No rigorous controls available No rigorous controls available Archival data on household characteristics in 3 neighborhoods from Graham, Gurian, et al Archival data on household characteristics in 3 neighborhoods from Graham, Gurian, et al Frequencies of risk factors compared between cases and baseline data Frequencies of risk factors compared between cases and baseline data –Limitations of this data set are recognized

91 incidents that included: 91 incidents that included: –212 intoxications –11 deaths Common causes: Use of gas heaters- 59% Use of improvised heaters- 18% Sealing windows and doors- 32%

Reported CO cases and average minimum temperature

Reported CO cases and daily minimum temperature

Statistical Analysis for Risk Factors Risk Factor Referent GroupOdds Ratio p-value Gas heaters No gas heater present 3.3< El Sol heatersOther gas heaters 3.9< Heater on at night Heater off at night Windows/doors sealed Not sealing windows/doors

Interventional Strategies from case-series study Most of the cases occur on cold nights Most of the cases occur on cold nights –Issue public warnings on radio/television during those nights Advice for families: Advice for families: –Do not seal windows and doors –Do not use the heater overnight –Replace old heaters with new ones Montoya, Gurian, Corella-Barud, and Mulla. “Unintentional Carbon Monoxide Poisoning Cases in Ciudad Juarez Mexico,” Southern Medical Journal, in press Montoya, Gurian, Corella-Barud, and Mulla. “Unintentional Carbon Monoxide Poisoning Cases in Ciudad Juarez Mexico,” Southern Medical Journal, in press

CO monitoring Week-long monitoring of 64 households for CO and temperature Week-long monitoring of 64 households for CO and temperature Collect information on heater type, heater usage, home characteristics, and health issues Collect information on heater type, heater usage, home characteristics, and health issues

67% of the homes exceeded the World Health Organization (WHO) 8- hour standard of 9 ppm 67% of the homes exceeded the World Health Organization (WHO) 8- hour standard of 9 ppm 17% of the homes exceeded the WHO 15-minute standard of 87 ppm 17% of the homes exceeded the WHO 15-minute standard of 87 ppm Potential for moderate health impacts is huge Potential for moderate health impacts is huge Exposure Assessment

Technology vs. Behavior Correlation between reported hours run and CO Correlation between reported hours run and CO –r=0.003 Weak correlation between delta T and CO Weak correlation between delta T and CO –r=.21 –p-value =0.1

Heater Type El Sol FM-210 heater used by 18% of the households El Sol FM-210 heater used by 18% of the households –Associated with higher CO levels –Odds ratio = 4.8 –P-value = 0.02 High exposures found with all types of heaters High exposures found with all types of heaters –wood heaters –Mexican gas heaters –European gas heaters –gas stoves

Future Directions Use Mental Models approach to design risk communication protocol (Morgan et al. 2002) Use Mental Models approach to design risk communication protocol (Morgan et al. 2002) Technological fixes Technological fixes –Newer, safer heaters –Alarms Can we facilitate these? Can we facilitate these? –Knowledge –Availability –Microcredit?

Financial Support: EPA SCERP, EPA Office of Air and Radiation, Paso del Norte Health Foundation Financial Support: EPA SCERP, EPA Office of Air and Radiation, Paso del Norte Health Foundation