Can secondhand smoke as an environmental factor increase autism risk?

PostedNovember 25, 2025

UpdatedNovember 25, 2025

ByMy Patient Advice

Author: Lucia Alvarez, MSc | Reviewed by: Dr. Rebecca Fernandez, MBBS

Yes, exposure to secondhand smoke & autism is an important area of study, with evidence suggesting that secondhand smoke may be a contributing environmental influence in increasing autism risk. It contains a mix of harmful chemicals, including nicotine, carbon monoxide, and heavy metals, all of which can affect both maternal and foetal health.

When a pregnant woman is exposed to passive smoke, these toxins can interfere with the development of the foetal brain, particularly during critical periods of growth. Even after birth, exposure to passive smoke can impact a child’s neurological development, potentially leading to behavioural or developmental differences, including autism-related traits.

How Secondhand Smoke Might Influence Autism Risk

Here are two key ways secondhand smoke may contribute to autism risk:

Disruption of brain development during pregnancy

The toxins in secondhand smoke can cross the placenta and affect the foetus, potentially leading to changes in brain structure and function. This exposure during pregnancy is thought to influence areas of the brain responsible for communication, social interactions, and sensory processing, traits commonly affected in autism.

Impaired neurological development after birth

Even after birth, exposure to secondhand smoke can impact a child’s development. It may lead to issues with attention, learning, or behaviour, which are all linked to autism traits, particularly in children who are genetically predisposed.

Understanding the link between secondhand smoke & autism highlights the need for effective public health measures to reduce exposure, especially during pregnancy and in the early years of a child’s life. Visit providers like Autism Detect for personal consultations and further guidance on screening and support.

For a deeper dive into the science, diagnosis, and full treatment landscape, read our complete guide to Environmental Factors.

Lucia Alvarez, MSc

Author

Lucia Alvarez is a clinical psychologist with a Master’s in Clinical Psychology and extensive experience providing evidence-based therapy and psychological assessment to children, adolescents, and adults. Skilled in CBT, DBT, and other therapeutic interventions, she has worked in hospital, community, and residential care settings. Her expertise includes grief counseling, anxiety management, and resilience-building, with a strong focus on creating safe, supportive environments to improve mental well-being.

All qualifications and professional experience stated above are authentic and verified by our editorial team. However, pseudonym and image likeness are used to protect the author's privacy.

Dr. Rebecca Fernandez, MBBS

Reviewer

Dr. Rebecca Fernandez is a UK-trained physician with an MBBS and experience in general surgery, cardiology, internal medicine, gynecology, intensive care, and emergency medicine. She has managed critically ill patients, stabilised acute trauma cases, and provided comprehensive inpatient and outpatient care. In psychiatry, Dr. Fernandez has worked with psychotic, mood, anxiety, and substance use disorders, applying evidence-based approaches such as CBT, ACT, and mindfulness-based therapies. Her skills span patient assessment, treatment planning, and the integration of digital health solutions to support mental well-being.

All qualifications and professional experience stated above are authentic and verified by our editorial team. However, pseudonym and image likeness are used to protect the reviewer's privacy.