The Health Department schedules mosquito spraying based on positive findings of West Nile Virus in mosquito traps placed around the city. Once located, the area around the positive finding is targeted for spraying on back-to-back nights (weather permitting) to help limit the spread of disease. Spraying is only one measure to help limit exposure, and health workers urge people to maintain vigilance in protecting themselves when going outside.

The City of Richardson Health Department has an established mosquito surveillance program in place to monitor mosquito populations in the community for the presence of West Nile virus and other mosquito-borne illnesses.

Using traps designed for mosquito collection, the Health Department regularly collects mosquito samples from geographically dispersed locations throughout the community. These samples are submitted to Dallas County Health and Human Services laboratories for analysis.

The Health Department also works closely with the Dallas County and Collin County Health Departments to monitor for the incidence of mosquito-borne illness in the human population.

The pesticide used degrades rapidly in the environment, and there is no cumulative or residual effect. However, for people concerned about exposure during aerial spraying, health officials suggest the following precautions:

• Minimize exposure. Avoid being outside, close windows and consider keeping pets inside while spraying occurs.
• If skin or clothes are exposed, wash them with soap and water.
• Rinse homegrown fruits and vegetables with water as a general precautionary measure.
• Cover small ornamental fish ponds.
• Because the chemical breaks down quickly in sunlight and water, no special precautions are suggested for outdoor swimming areas.

The Health Department schedules spraying events during overnight hours to limit exposure to people who may wish to avoid contact with the pesticide used to control mosquito populations. Spraying events begin at 9 p.m. with the goal of ending by 5 a.m., depending upon the size and the number of the spray areas.

The City uses several communication tools to inform the public about planned spraying events. News releases are sent to local media and posted on the City website; information is sent electronically to homeowners and neighborhood associations, as well as to subscribers of the Week In Review/City News e-notification list; and information is posted on the Richardson Today Facebook and Twitter. The City will also post on NextDoor to those areas affected by sprayings.

Health Department staff sprays only targeted areas. Targeted areas include areas where West Nile virus has been isolated in a mosquito sample or if a case of illness is  confirmed in humans. Since spraying does not eliminate all mosquitoes, it is important that citizens do what they can to protect themselves and that mosquito breeding sources around the home be eliminated. If spraying is indicated, the Health Department applies an EPA-approved pesticides with a low toxicity. Spraying events begin at 9 p.m. with the goal of ending by 5 a.m., depending upon the size and the number of the spray areas.

The City utilizes an ultra-low volume fogger that disperses pesticide, following Centers for Disease Control and Prevention (CDC) and Environmental Protection Agency (EPA) guidelines, which is effective at reducing mosquito populations and is sensitive to the environment.

Spraying is typically conducted using ground-based foggers mounted in trucks. However, in certain emergency situations aerial-based spraying is considered a safe and effective way to control mosquitoes in larger geographical areas.

The City uses a variety of products. Pesticides that are used for mosquito control have been approved by the EPA not to pose an unreasonable risk to human health. People who are concerned about exposure to a pesticide, such as those with chemical sensitivity or breathing conditions such as asthma, can reduce their potential for exposure by staying indoors during the application period.

The Health Department schedules spraying events during overnight hours to limit exposure to people who may wish to avoid contact with the pesticide used to control mosquito populations. Spraying events begin at 9 p.m. with the goal of ending by 5 a.m., depending upon the size and the number of the spray areas.