Evacuation decisions in a chemical air pollution incident: cross sectional survey.
OBJECTIVE
To compare the health outcomes in sheltered and evacuated populations after a chemical incident in a plastics factory.


METHODS
Cross sectional survey.


METHODS
Urban area in southwest England.


METHODS
1750 residents from the area exposed to the chemical smoke, of which 472 were evacuated and the remaining 1278 were advised to shelter indoors.


METHODS
Number of adverse health symptoms. A case was defined by the presence of four or more symptoms.


RESULTS
1096 residents (63%; 299 evacuated, 797 sheltered) provided data for analyses. The mean symptom score and proportion of cases were higher in evacuated people than in the sheltered population (evacuated: symptom score 1.9, cases 19.7% (n = 59); sheltered: symptom score 1.0, cases 9.5% (n = 76); P < 0.001 for both). The difference between the two groups attenuated markedly at the end of two weeks from the start of the incident. The two main modifiable risk factors for the odds of becoming a case were evacuation (odds ratio 2.5, 95% confidence interval 1.7 to 3.8) and direct exposure to smoke for more than two hours on the first day of the incident (2.0, 1.7 to 2.3). The distance of residence from the factory or level of exposure before intervention (first six hours) had little effect on the odds of a person becoming a case.


CONCLUSIONS
Sheltering may have been a better protective action than evacuation in this chemical incident, which is consistent with the prevailing expert view. Although this study has limitations, it is based on a real event. Evacuations carry their own risks and resource implications; increased awareness may help to reduce unnecessary evacuations in the future.
Kinra
S
S
Department of Social Medicine, University of Bristol, Bristol BS8 2PR. Sanjay.Kinra@bristol.ac.uk
Lewendon
G
G
Nelder
R
R
Herriott
N
N
Mohan
R
R
Hort
M
M
Harrison
S
S
Murray
V
V
D000393:Air Pollutants / Q000009:adverse effects*; D002617:Chemical Industry; D003430:Cross-Sectional Studies; D003657:Decision Making; D004739:England; D004781:Environmental Exposure / Q000009:adverse effects*; D006304:Health Status; D006801:Humans; D010969:Plastics; D011379:Prognosis; D012307:Risk Factors; D012906:Smoke / Q000009:adverse effects*; D014187:Transportation of Patients / Q000706:statistics & numerical data*; D014504:Urban Health
D000393:Air Pollutants; D010969:Plastics; D012906:Smoke