Some Facts about Spraying

"West Nile virus puts people's lives and livelihoods at stake. Public health authorities who implement integrated mosquito management techniques, including the spraying of insecticides for control of adult mosquitoes, if needed, should be commended for doing their job protecting the community's health."
- Allen James, RISE President

"The recent emergence and spread of mosquito-borne diseases, such as West Nile virus, underscores the need to recognize the vital contributions safe and effective mosquito programs have made to the health of our nation's citizens. If such diseases are to ever rise to epidemic heights in the United States, we have only ourselves to blame because the means to control them are fully within out grasp - and our citizenry deserves no less."
- Joe Conlon, entomologist serving as technical advisor for the American Mosquito Control Association

The EPA's rigorous pesticide safety review process is designed to ensure that registered mosquitocides used according to label directions and precautions can further reduce disease-carrying mosquito populations, thus protecting public health.

Adulticides

• Adulticides are part of an integrated mosquito management (IMM) program and are used only when necessary after other IMM measures such as source reduction and larviciding have not reduced the biting mosquito population.
• Adulticides are used by licensed professional applicators who must follow state and EPA requirements. The US EPA has evaluated adulticides for their safety and has determined that they do not pose an unreasonable risk to humans, animals or the environment if used according to the product label directions. 
  
• The decision by communities or mosquito control organizations to use pesticides to control adult mosquitoes is generally based on surveillance information and documentation of West Nile virus activity. If West Nile virus is found at levels that indicate a threat to human health, local applications of pesticides may be undertaken to prevent people from becoming infected. 
  
• Overall, adulticides are highly effective in killing mosquitoes. The effectiveness of adulticides depends on a number of variables including which species of mosquitoes are present; what pest control products are used; when and how often pesticides are applied; weather conditions; and the density of homes and streets in a community. Application of adulticides is considered an effective means of temporarily reducing adult mosquito populations and has been carried out in the U.S. and other countries for many years for nuisance reasons and more importantly, as a means of reducing and preventing mosquito-borne diseases, such as West Nile virus.
• Depending on the situation, mosquito control officials may safely apply these insecticides from spray equipment mounted on trucks, airplanes or helicopters. In the small amounts used, risks to people and pets are extremely low. Application from aircraft may only be performed according to Federal Aviation Administration regulations, by county mosquito control commissions, equivalent county units or the State Mosquito Control Commission. To insure the droplets descend from the aircraft to the areas of mosquito activity, these applications are made near sunset or in the early morning.
• To be successful, mosquito control officials apply insecticides under proper environmental conditions (e.g., temperature and wind) and at the time of day when the target species is most active. Officials apply these pesticides with carefully calibrated equipment that generates the proper-sized insecticide droplets to impinge on adult mosquitoes while they are at rest or flying. If the droplets are too large, they will fall to the ground. If they are too small, the prevailing winds will carry them away from the target area. Once the insecticide spray mist dissipates, it breaks down in the environment (generally within 24 hours) producing little residual effect.
  
• New technology is making mosquito control more precise, accurate and safe. Mosquito control agencies are using Global Positioning Systems (GPS) on fixed-wing aircraft to improve aerial applications and more accurately target mosquito populations while reducing non-target impacts. Lasers are being used to measure droplet size of insecticide dispersed from aircraft, thus reducing the size of droplets dispersed and the amount of insecticide sprayed. Night-vision goggles allow pilots to treat mosquitoes during evening hours when they're most active and give pilots a better visual perspective to accomplish spray missions more efficiently.
• For most members of the public, there is no need to relocate during mosquito control spraying. Mosquito control pesticides have been evaluated for this use and found to pose minimal risks to human health and the environment when used according to label directions. For example, EPA has estimated the exposure and risks to both adults and children posed by ULV aerial and ground applications of the insecticides malathion and naled. For all the exposure scenarios considered, exposures ranged from 100 to 10,000 times below an amount of pesticide that might pose a health concern. These estimates assumed several spraying events over a period of weeks, and also assumed that a toddler would ingest some soil and grass in addition to dermal exposure. Other mosquito control pesticides pose similarly low risks. 
  
• Human exposure in residential areas is also uncommon because of the very low application rates, ultra low-volume methods (ULV), treatment at night when people are indoors, pesticide applicator training and, in most locations, public prenotification before application.