Mosquito Pesticide Spraying on the Westside of Salt Lake City

Another “Downwinder” Threat to Utahns

“New research suggests that the use of airplanes to spray anti-mosquito pesticides may increase the risk of autism spectrum disorder and developmental delays among children.”
American Academy of Pediatrics, conference presentation 20161

WHEN: Wednesday, April 1411:00 AM MT
WHERE: Zoom Video Conference

(Salt Lake City, UT) –On Wednesday, April 14, at 11:00 AM MT, Physicians from the Board of Directors of the Utah Physicians for a Healthy Environment (UPHE) will discuss a report recently published on UPHE’s website.

The Salt Lake City Mosquito Abatement District (SLCMAD)’s strategy for mosquito control is badly outdated, scientifically flawed, and represents a chronic and recurring hazard to the health of residents in the Salt Lake Valley. We are calling on them to stop pesticide spraying for mosquitoes.

SLCMAD states it was created in 1923 to “protect Salt Lake City residents from the large numbers of these pestiferous mosquitoes.” The district seems to be using a mandate that is nearly 100 years old as part of their justification for their spraying strategy. Obviously much has changed in the last 100 years. This mandate, and the mere continued presence of mosquitoes in their natural habitat in the Northwest Quadrant does not justify pesticide spraying.

In February UPHE became alarmed after learning the SLCMAD was proposing to invoke the US Air Force in launching aerial spraying over the Northwest Quadrant. That proposal was withdrawn after widespread public opposition. However, UPHE has learned that the district has conducted a massive aerial spraying of pesticides using private planes, every year for decades over much of the Northwest Quadrant and intends to continue that, despite the fact that by their own admission it is no longer effective.  Infants, children, and pregnant mothers on the West side, North Salt Lake, and West Bountiful are being exposed to pesticides that are proven hazardous to public health, and to young brain development in particular, without any offsetting benefit. In fact, pesticides have lost their effectiveness in controlling mosquitoes and in suppressing the already declining case numbers of West Nile Virus. 

Dr. Brian Moench, UPHE Founder and President and the participating physicians will explain their request, driven by medical science. According to Dr. Moench, President and Founder of UPHE, “Aerial spraying of toxic pesticides in a vain attempt to control mosquitoes is not protecting public health. The practice is an institutionalized relic of the 1950s just like atmospheric nuclear bomb testing. In fact there is significant overlap between the disease potential of pesticides and radiation. The public should look at this as yet another way that Utah families are becoming downwinder victims of poor public policy.” “Claims of pesticide safety use faulty logic and faulty science. It’s been 60 years since Rachael Carson published Silent Spring and still government agencies in Utah are putting deadly chemicals in our environment with little to no thought about the cumulative negative impact of these chemicals on our communities or the poor efficacy of the practice,” said Dr. Courtney Henley, UPHE board member. 

Executive Summary

We believe the evidence is clear and overwhelming:

  • Pesticides in general, including those used by SLCMAD, represent a widespread risk to human health even at low doses, especially for fetuses and infants.
  • The VOCs from pesticide spraying is a significant contributor to local air pollution.
  • Spraying is not effective in reducing mosquito populations.
  • We must not allow a cure worse than the disease. The incidence of severe outcomes from West Nile Virus is so low that preventing those outcomes should not be allowed to eclipse the long list of other health and environmental concerns from pesticide use.
  • Spraying does not reduce the incidence of WNV.
  • Claims of safety for pesticide spraying use faulty logic and outdated, faulty science.
  • There are multiple oversights, inadequacies, omissions, inconsistencies, and errors in the SLCMAD’s Environmental Assessment of pesticide use.
  • Pesticide spraying has adverse impacts on beneficial insects, bird populations, wildlife, the ecosystem of the Great Salt Lake and beyond.
  • There are better ways to Control Mosquitoes.


The scientific and empirical evidence is overwhelming that spraying adulticides to kill mosquitoes, especially aerial spraying, is ineffective, and can be even counterproductive, over the long term, and even the short term, to both goals of controlling mosquito populations and preventing West Nile Virus. Furthermore, the medical literature strongly indicates that routine aerial spraying over Salt Lake City’s airshed represents a broad-based danger to public health. Utah Physicians for a Healthy Environment (UPHE) implore SLCMAD to end all of their insecticide spraying for mosquitoes, whether from back packs, trucks, or airplanes. This practice should be stopped immediately.


  • Brian Moench, M.D., Board President, UPHE
  • John Macfarlane M.D., Neurosurgeon, Board Member UPHE
  • Kirtly Jones, M.D., Professor Emerita Dept. of Obstetrics and Gynecology, Board Member UPHE
  • Courtney Henley, M.D., Anesthesiologist, Board Member UPHE
  • Tom E Nelson M.D., Emergency Medicine Physician, Board Member UPHE

INTERVIEWS:   Press is encouraged to join the video conference at 10:55 AM MT. Speakers will be available for questions following the video conference. Press will initially be muted when they join the video conference, and will later be unmuted during the Q&A section to ask questions. The physicians will speak for about 20 minutes total.


Utah Physicians for a Healthy Environment was formed in 2007 during one of Utah’s worse inversions.  The organization consists of approximately 400 medical professionals within Utah, and another 4,000 supporting members of the public.  UPHEis dedicated to protecting the health and well being of the citizens of Utah by promoting science- based health education and interventions that result in progressive and measurable improvements to the environment and our health. UPHE can be found at or on Facebook.