There has been growing evidence that the brain is vulnerable to the effects of air pollution. There have also been connections established between the components of air pollution and the diagnosis of autism. It has been seen that ultrafine particles have been especially detrimentally during the development of a child in the third trimester of a pregnancy. To test this, researchers exposed pregnant mice to ultrafine particles. The results showed that the young mice developed brain inflammation and microglial activation. They had a reduced corpus callosum size and associated hypomyelination. They had abnormal white matter development, elevated glutamate levels, excitatory/inhibitory imbalances, increased astrocytic activation in the amygdala, and repetitive/impulsive behaviors. This symptoms are consistent with autism, as well as other disorders like schizophrenia, attention deficit disorder, etc. These results demonstrate the negative affects of air pollution. 

Allen, J.L., Oberdörster, G., Morris-Schafer., K., Wong, C., Klocke, C., Sobolewski, M., Conrad, K., Mayer-Proschel, M., Cory-Slechta, D.A. "Developmental Neurotoxicity of Inhaled Ambient Ultrafine Particle Air Pollution: Parallels with Neuropathological and Behavioral Features of Autism and Other Neurodevelopmental Disorders." Neurotoxicology, vol. 59, 2017, pp. 140-154. 

The purpose of this study was to focus on how particles of pollution affected cognitive functions, learning memory, and and impulsive-like behaviors in adult mice. They exposed the adult mice to concentrated levels of pollution called UFPs for a few hours each day. They then assessed the various behavioral measures I mentioned above, as well as, locomotor activity and motivation.  The results indicated that male mice showed specific impairments in learning and memory, especially during changes in reinforcement contingencies, and these changes were not associated with differences in locomotor function or motivation. Female mice did not exhibit cognitive decline, but displayed altered motivation-related behaviors. 

Cory-Slechta, D.A., Allen, J.L., Conrad, K., Marvin, E., Sobolewski, M, "Developmental Exposure to Low Level Ambient Ultrafine Particle Air Pollution and Cognitive Dysfunction." Neurotoxicology, vol. 69, 2018, pp. 217-231. 

This study noted that previous studies have used ultrafine pollution particles to test the effect of pollution on the brain. This study wanted to determine if a specific particle in the ultrafine particles was responsible for the negative affects observed. The particle in this case was ultrafine elemental carbon. The researchers exposed mice to concentrated elemental carbon for a few  hours each day. They assessed various behavioral outcomes, including locomotor activity, short-term memory, anxiety-like behavior, learning, timing, and impulsivity. They also examined neuropathological markers, like inflammation and myelin basic protein expression in the corpus callosum and lateral ventricle area. The results showed that both male and female mice exposed to the pollutant didn't significantly change the brain or behavior. This suggests that ultrafine elemental carbon isn't responsible for the negative effects seen from air pollution. 

Morris-Schaffer, K., Merrill , A., Jew, K., Wong, C., Conrad, K., Harvey, K., Marvin, E., Sobolewski, M., Oberdörster, G., Elder, A., Cory-Slechta , D.A. "Effects of neonatal inhalation exposure to ultrafine carbon particles on pathology and behavioral outcomes in C57BL/6J mice." Particle and Fibre Toxicology, vol. 16, 2019, pp. 1-15.