The Midwest's Invisible Crisis: Agriculture, Air Pollution, and the Developing Autistic Brain

Agricultural ammonia is unregulated, increasing, and responsible for 40% of all PM2.5 in the Midwest. It is 4x the national average. The specific pollutant it creates, ammonium nitrate, has been associated with poorer learning and memory, in children, while PM2.5 exposure in autistic children has been linked to greater symptom severity, hospitalization-level aggravation, and measurable deficits in daily living and socialization skills.

Moreover, exposure does not rely on living on or within close proximity to a farm. This exposure is happening at the regional level.

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THE NUMBERS

Finding	Source
Agricultural ammonia contributes an estimated 40% of the Midwest’s PM2.5 burden, about 4× agriculture’s average contribution nationally	Vo & Christiansen, 2024
Atmospheric ammonia across the Midwest increased 43% from 2007 to 2019	Vo & Christiansen, 2024
Previously declining winter PM2.5 and particulate-nitrate trends reversed after 2014 alongside increasing ammonia emissions	Vo & Christiansen, 2024
Particulate nitrate can account for up to 40% of winter PM2.5 mass across the agricultural Midwest	Vo & Christiansen, 2026
In more than 8,500 U.S. children, higher ammonium-nitrate exposure produced the study’s most robust association with poorer learning and memory	Sukumaran et al., 2024
Among children already diagnosed with autism, higher PM2.5 exposure during the first three years of life correlated with greater autism symptom severity on the Childhood Autism Rating Scale	Geng et al., 2019
A longitudinal study of 2,750 young people found greater particulate exposure associated with more severe ASD and ADHD symptoms over time	Li et al., 2023
A 10 μg/m³ short-term increase in PM2.5 was associated with a 17% higher risk of ASD-related hospital admission in children ages 5–14, which researchers used as a measure of symptom aggravation	Kim et al., 2022
Among 658 U.S. children with autism, early-life PM2.5 exposure was associated with poorer daily living skills and socialization	McGuinn et al., 2022
Across six studies representing 4,860 children, each 1 μg/m³ increase in PM2.5 was associated with approximately 0.27 fewer Full-Scale IQ points	Alter et al., 2024
Meta-analysis found ASD risk increased approximately 64% per 10 μg/m³ higher PM2.5 during early childhood	Lin et al., 2021
Agricultural ammonia emissions are unregulated at the federal level	Vo & Christiansen, 2024
Approximately 2.1 million acres of Kansas-Oklahoma Flint Hills rangeland are burned each year; Kansas health officials specifically identify children as more vulnerable to resulting particulate pollution.	KDHE, 2026

THE ARGUMENT IN FIVE SENTENCES

1. PM2.5 exposure has been linked to cognitive harm in children and, in autistic children specifically, it has been linked to increased symptom severity, acute hospitalizations, and measurable deficits in the skills needed for daily living.

   
   

2. Agricultural ammonia accounts for an estimated 40% of the Midwest’s PM2.5 burden, about four times agriculture’s average contribution nationally.

   
   

3. Particulate nitrate formed through this agricultural pollution can account for up to 40% of winter PM2.5 across the Midwest.

   
   

4. Unlike every other major pollution source, agricultural ammonia is not federally regulated.

   
   

5. Once these microscopic particles form in the atmosphere, they become part of the regional air.

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THE CONCERN

Children across the Midwest are breathing PM2.5, tiny particles that can reach deep into the lungs and enter the blood. Agriculture adds about four times more to this pollution in the Midwest than it does nationally. Research has linked exposure to poorer learning, memory and IQ, more severe autism symptoms, problems with everyday skills, and hospitalization.

Yet, many people are unaware of this. And becoming aware can feel numbing when the threat is regional and largely beyond our individual control. But without uncovering the uncomfortable reality, we cannot change it.

Full long-form analysis and expanded references are available in the Evernorth Resource Library.

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Works Cited

Alter, N. C., Whitman, E. M., Bellinger, D. C., & Landrigan, P. J. (2024). Quantifying the association between PM2.5 air pollution and IQ loss in children: A systematic review and meta-analysis. Environmental Health, 23, 101. https://doi.org/10.1186/s12940-024-01122-x

Geng, R., Fang, S., & Li, G. (2019). The association between particulate matter 2.5 exposure and children with autism spectrum disorder. International Journal of Developmental Neuroscience, 75, 59–63. https://doi.org/10.1016/j.ijdevneu.2019.05.003

Kim, K.-N., et al. (2022). Effects of short-term exposure to air pollution on hospital admissions for autism spectrum disorder in Korean school-aged children: A nationwide time-series study. BMJ Open, 12(9), e058286. https://doi.org/10.1136/bmjopen-2021-058286

Kansas Department of Health and Environment. (2026, February 26). Health advisory, safety tips for prescribed fire season in Flint Hills.

Li, Y., et al. (2023). Longitudinal effects of environmental noise and air pollution exposure on autism spectrum disorder and attention-deficit/hyperactivity disorder during adolescence and early adulthood: The TRAILS study. Environmental Research, 227, 115704. https://doi.org/10.1016/j.envres.2023.115704

Lin, C.-K., Chang, Y.-T., Lee, F.-S., Chen, S.-T., & Christiani, D. C. (2021). Association between exposure to ambient particulate matters and risks of autism spectrum disorder in children: A systematic review and exposure-response meta-analysis. Environmental Research Letters, 16(6), 063003. https://doi.org/10.1088/1748-9326/abfcf7

McGuinn, L. A., Wiggins, L. D., Volk, H. E., et al. (2022). Pre- and postnatal fine particulate matter exposure and childhood cognitive and adaptive function. International Journal of Environmental Research and Public Health, 19(7), 3748. https://doi.org/10.3390/ijerph19073748

Sukumaran, K., Botternhorn, K. L., Schwartz, J., et al. (2024). Associations between fine particulate matter components, their sources, and cognitive outcomes in children ages 9–10 years old from the United States. Environmental Health Perspectives, 132(10), 107009. https://doi.org/10.1289/EHP14418

Vo, T., & Christiansen, A. E. (2024). Impact of recent agricultural ammonia increases on fine particulate matter burden over the Midwestern United States. ACS Earth and Space Chemistry, 8(11), 2209–2217. https://doi.org/10.1021/acsearthspacechem.4c00180

Vo, T., & Christiansen, A. E. (2026). The changing sensitivity of wintertime particulate nitrate to precursor emissions diagnosed via GEOS-Chem and satellite observations of ammonia and nitrogen dioxide over the Midwestern United States. Atmospheric Chemistry and Physics, 26, 9493–9510. https://doi.org/10.5194/acp-26-9493-2026