Noise and Air Pollution Linked to Mental Health Conditions in Young People

Exposure to air and noise pollution early in life may be linked to several common mental health problems in adolescence and early adulthood, according to a longitudinal birth cohort study.

An analysis of more than 9,000 participants in England found that higher exposure to fine particulate matter (PM_2.5) — a common pollutant with well-established health impacts — during pregnancy was associated with higher odds of psychotic experiences (adjusted OR [AOR] 1.11, 95% CI 1.04-1.19, P=0.002) and depression (AOR 1.10, 95% CI 1.02-1.18, P=0.01), according to Joanne Newbury, PhD, of Bristol Medical School in England, and colleagues.

Similarly, exposure to fine particulate matter during childhood was associated with higher rates of psychotic experiences (AOR 1.09, 95% CI 1.00-1.10; P=0.04), but the association appeared to weaken after adjusting for pregnancy exposure, the authors reported in JAMA Network Open.

“Early-life exposure could be detrimental to mental health given the extensive brain development and epigenetic processes that occur in utero and during infancy,” they wrote, adding that “the results of this cohort study provide novel evidence that early-life exposure to particulate matter is prospectively associated with the development of psychotic experiences and depression in youth.”

Air pollution was associated primarily with psychotic experiences and depression, but noise pollution was more likely to be associated with anxiety in adolescence and early adulthood.

Individuals exposed to higher levels of noise pollution in childhood (AOR 1.19, 95% CI 1.03-1.38, P=0.02) and in adolescence (AOR 1.22, 95% CI 1.02-1.45, P=0.03) had elevated odds for anxiety. However, that adolescent exposure was also weaker after adjusting for exposure during pregnancy and childhood.

They also noted there was no association between exposure to higher levels of air pollution and anxiety.

Martin Clift, PhD, of Swansea University in England who was not involved in the study, said that the paper highlighted the need for more consideration of health consequences related to these exposures.

“As noted by the authors, this is an area that has received a lot of recent attention, yet there remains a large void of knowledge,” Clift said in a post on the U.K. Science Media Center website. “[The paper] highlights that some of the most dominant air pollutants … can impact different mental health diagnoses, but that time-of-life is particularly important as to how each individual air pollutant may impact this diagnosis.”

He added that the findings emphasize that there is a need to understand the impact of exposure to different forms of pollution during different stages of human development beyond the more well-known physical risks posed by air and noise pollution.

The study is among just a few to investigate these associations, the authors noted, and the findings show a critical need to better understand the potential pathways for these negative mental health outcomes associated with high pollutant exposure over time.

“The opportunity for intervention is potentially enormous,” the authors concluded. “There is now a pressing need for further longitudinal research using more precise measures of air and noise pollution and for replication using quasi-experimental designs.”

The researchers collected data from participants in the Avon Longitudinal Study of Parents and Children U.K. birth cohort, which enrolled pregnant women in and around the city of Bristol, England between April 1, 1991 and December 31, 1992. In total, there were 9,065 participants with a mean age of 24.5 years at follow-up and 51.4% were female.

Among the total study population, 19.5% of participants reported psychotic experiences, 11.4% reported depression, and 9.7% reported anxiety.

Psychotic experiences, depression, and anxiety were measured at ages 13, 18, and 24 years. Psychotic experiences were measured using a semi-structured interview, which consisted of 12 core items about hallucinations, delusions, and thought interference. The interviews were rated using the Schedule for Clinical Assessment in Neuropsychiatry version 2.0. The Diagnostic and Statistical Manual of Mental Disorders and the International Statistical Classification of Diseases, Tenth Revision were used to determine depression and anxiety scores.

Air pollution was estimated using the Effects of Low-Level Air Pollution: A Study in Europe (ELAPSE) model, and noise pollution was estimated using the U.K. Government’s Department for Environment, Food and Rural Affairs 2006 road traffic noise map. The authors also adjusted for several individual, family and neighborhood-level covariates.

The study had several limitations including potential effects of residual confounding factors and population selection bias since the participants were from a more affluent and less diverse U.K. population.