Transcript 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.

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
– 1,381 intoxicated by CO
– 167 deaths by CO


Associated with unvented heaters
Little systematic study
in U.S.-México border
region
Objectives


Develop strategy to mitigate health
risks
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
2. Monitor CO levels at 64 households

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
Realistic-will be implemented by subject
population
Case-series study

Case reports obtained for 2003-2004
winter season
– Information on cause, date, time, location

Summarized common factors
Baseline data



No rigorous controls available
Archival data on household
characteristics in 3 neighborhoods
from Graham, Gurian, et al. 2004
Frequencies of risk factors compared
between cases and baseline data
– Limitations of this data set are recognized

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%
50
60
55
50
45
40
35
30
25
20
Cases
40
30
20
10
0
OCT
NOV
DEC
JAN
FEB
Month
Cases
Average minimum temperature
Temperature (F)
Reported CO cases and average
minimum temperature
Number of Incidents
Reported CO cases and daily
minimum temperature
12
10
8
6
4
2
0
10
15
20
25
30
35
40
Temperature (F)
45
50
55
60
Statistical Analysis for Risk
Factors
Risk Factor
Gas heaters
Referent Group
No gas heater present
El Sol heaters
Other gas heaters
Heater on at
night
Heater off at night
Windows/doors
sealed
Not sealing windows/doors
Odds Ratio
p-value
3.3
< 0.001
3.9
< 0.001
3.9
0.026
3.2
0.006
Interventional Strategies
from case-series study

Most of the cases occur on cold nights
– Issue public warnings on radio/television during
those nights

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
CO monitoring


Week-long monitoring of 64
households for CO and temperature
Collect information on heater type,
heater usage, home characteristics,
and health issues
Exposure Assessment



67% of the homes exceeded the
World Health Organization (WHO) 8hour standard of 9 ppm
17% of the homes exceeded the WHO
15-minute standard of 87 ppm
Potential for moderate health impacts
is huge
Technology vs. Behavior

Correlation between reported hours
run and CO
– r=0.003

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
– Associated with higher CO levels
– Odds ratio = 4.8
– P-value = 0.02

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)
Technological fixes
– Newer, safer heaters
– Alarms

Can we facilitate these?
– Knowledge
– Availability
– Microcredit?

Financial Support: EPA SCERP, EPA
Office of Air and Radiation, Paso del
Norte Health Foundation