Use of syndromic surveillance to monitor the health impact of wildfires, San Diego County, 2007

Recent years' events have led to increased focus on disaster preparedness, including the need for population health monitoring. During October 2007, numerous wildfires burned throughout San Diego County. A large proportion of the population, if not directly threatened by flames, was vulnerable to adverse health outcomes related to exposure to smoke and poor air quality. The County of San Diego Public Health Services (COSDPHS) turned to its existing syndromic surveillance system to track the population's health. COSDPHS receives daily data files from eight emergency departments and three 911 Call Centers throughout the county. Chief complaint data were grouped into syndromes; asthma/COPD, total respiratory visits, chest pain, and total visits were monitored. Statistical methods, including P-Chart, U-Chart, EWMA, and CUSUM, were used to detect anomalies. Trends were monitored by age and zip code. On 10/22, the peak day of measured air particulate matter, asthma/COPD visits increased 200% over the 30-day mean, respiratory visits increased 100+%, total visits increased 20%. Differential increases in respiratory visits were observed by age, with little increase in visits among children, suggesting that school closures and recommendations to stay indoors were successful. Visits for chest pain did not increase. Total 911 call volume increased 100%. Counts remained high for several days then returned to normal levels. These data helped characterize the health and healthcare utilization impact of the fires and provided county officials timely information for decision making in response to the fires and planning for future disasters.