Modeling duration of time lived in a residence, a community and mobility in rural areas of Merced and Ventura, California to assess potential health risks to airborne contaminants

Abstract

A de novo population mobility survey of 800 households (random digit dialing-based phone interviews) was conducted in high demand areas of the agricultural fumigant, 1,3-dichloropropene (1,3-D) in Merced and Ventura counties of California. The survey included approximately 20 questions relating to the length of time individuals had lived in the high demand areas in each county, and also relating to weekly and annual mobility patterns. Lifetime inhalation exposures to 1,3-D are determined, in part, by the number of years individuals spend in an area where the fumigant is used. The purpose of the survey was to provide location-specific data for probabilistic modeling of long-term inhalation exposures to 1,3-D. The survey found that the majority of residents do not live in a high demand area or in the same house (99.99%) for 70years (a default assumption used by some regulatory agencies). It was also observed that residents move frequently and are mobile day-to-day and week-to-week, within the use area. Finally, estimates of total residency duration, derived from the survey results indicate that median times spent within a high demand area (which could include more than one residential location) were 18 and 26years for Ventura and Merced high demand areas, respectively. The average time spent in the high demand areas was 22 and 27years for the Ventura and Merced community, respectively. Less than 0.01% of the populations in either of the high demand areas spend 70years in the same house.