Air pollution and emotional behavior in adolescents across the U.S

Abstract

Recent studies have linked air pollution to increased risk for behavioral problems during development, albeit with inconsistent findings. Additional longitudinal studies are needed that consider how emotional behaviors may be affected when exposure coincides with the transition to adolescence - a vulnerable time for developing mental health difficulties. This study examines how annual average PM_2.5 and NO₂ exposure at ages 9-10 years relates to internalizing and externalizing behaviors over a 2-year follow-up period in a large, nationwide U.S. sample of participants from the Adolescent Brain Cognitive Development (ABCD) Study^®. Air pollution exposure was estimated based on the residential address of each participant using an ensemble-based modeling approach. Caregivers answered questions from the Child Behavior Checklist (CBCL) at baseline and annually for two follow-up sessions for a total of 3 waves of data; from the CBCL we obtained scores on internalizing and externalizing problems plus 5 syndrome scales (anxious/depressed, withdrawn/depressed, rule-breaking behavior, aggressive behavior, and attention problems). Zero-inflated negative binomial models were used to examine both the main effect of age as well as the interaction of age with each pollutant on behavior while adjusting for various socioeconomic and demographic characteristics. Overall, the pollution effects moderated the main effects of age with higher levels of PM_2.5 and NO₂ leading to an even greater likelihood of having no behavioral problems (i.e., score of zero) with age over time, as well as fewer problems when problems are present as the child ages. Albeit this was on the order equal to or less than a 1-point change. Thus, one year of annual exposure at 9-10 years is linked with very small change in emotional behaviors in early adolescence, which may be of little clinical relevance.

Keywords: adolescence; air pollution; externalizing; internalizing; neurodevelopment.

Figure 1

Significant results for internalizing and externalizing behavior. NO₂ is set to the WHO standard (5.33 ppd) for the PM_2.5-by-age models and PM_2.5 is set to the WHO standard (5 μg/m³) for the NO₂-by-age models. Column 1) Displays the estimated probability of being in the absolute zero category as compared to the non-zero category (i.e., any value for CBCL scores). Column 2) Displays the estimated CBCL score for subjects whose scores were in the non-zero category. Numerous results are presented which include: a) PM_2.5-by-age interaction which displays differences in 9 and 12 years-of-age for the WHO recommended PM_2.5 levels - 5 μg/m³ (light blue) - versus the EPA’s - 12 μg/m³ (dark blue); b) NO₂-by-age interaction which displays differences in 9 and 12 years-of-age for the WHO recommended NO₂ levels - 5.33 ppd (light purple) - versus the 90^th percentile NO₂ level in our sample - 26.1 ppd (dark purple) (The EPA level is 53 ppd which is outside our sample range). All graphs display percent change with age. All covariates held constant at the largest N category (sex = “male”, race/ethnicity = ‘White’, caregiver education = ‘Post Graduate Degree’, caregiver employment = “Employed”, and household income = “≥$100K”), and mean for neighborhood safety ($\overline{x}=3.88$)

Figure 2

Significant results for anxious/depressed and withdrawn/depressed. NO₂ is set to the WHO standard (5.33 ppd) for the PM_2.5-by-age models and PM_2.5 is set to the WHO standard (5 μg/m³) for the NO₂-by-age models. Column 1) Displays the estimated probability of being in the absolute zero category as compared to the non-zero category (i.e., any value for CBCL scores). Column 2) Displays the estimated CBCL score for subjects whose scores were in the non-zero category. Numerous results are presented which include: a) PM_2.5-by-age interaction which displays differences in 9 and 12 years-of-age for the WHO recommended PM_2.5 levels - 5 ?μg/m³ (light blue) - versus the EPA’s - 12 μg/m³ (dark blue); b) NO₂-by-age interaction which displays differences in 9 and 12 years-of-age for the WHO recommended NO₂ levels - 5.33 ppd (light purple) - versus the 90^th percentile NO₂ level in our sample - 26.1 ppd (dark purple) (The EPA level is 53 ppd which is outside our sample range). All graphs display percent change with age. All covariates held constant at the largest N category (sex = “male”, race/ethnicity = ‘White’, caregiver education = ‘Post Graduate Degree’, caregiver employment = “Employed”, and household income = “≥$100K”), and mean for neighborhood safety ($\overline{x}=3.88$).

Figure 3

Significant results for rule-breaking behavior, aggressive behavior, and attention problems. NO₂ is set to the WHO standard (5.33 ppd) for the PM_2.5-by-age models and PM_2.5 is set to the WHO standard (5 μg/m³) for the NO₂-by-age models. Column 1) Displays the estimated probability of being in the absolute zero category as compared to the non-zero category (i.e., any value for CBCL scores). Column 2) Displays the estimated CBCL score for subjects whose scores were in the non-zero category. The only significant interactions seen for these subscales were the NO₂-by-age interaction which displays differences in 9 and 12 years-of-age for the WHO recommended NO₂ levels - 5.33 ppd (light purple) - versus the 90^th percentile NO₂ level in our sample - 26.1 ppd (dark purple) (The EPA level is 53 ppd which is outside our sample range). All graphs display percent change with age. All covariates held constant at the largest N category (sex = “male”, race/ethnicity = ‘White’, caregiver education = ‘Post Graduate Degree’, caregiver employment = “Employed”, and household income = “≥$100K”), and mean for neighborhood safety ($\overline{x}=3.88$).