1. Air quality is a growing concern for health and environment and is one of the modifiable environmental factors. There is growing evidence that a complex interplay of genetic and epigenetic factors like environmental factors, underlies the pathophysiology of ASD. Behavioural issues, sleep habits and cognitive abilities play a significant role in the quality of life of both the affected children and their caregivers
2. Few studies have shown that there is an increased incidence of ASD in children born to mothers exposed to higher levels of air pollution in pregnancy. However, no studies on the effect of air quality on the severity of autism. There are limited studies on the association of air pollution with childhood behaviour and cognitive abilities, especially in neurodevelopmental disorders. No evidence on the impact of air quality on the effectiveness of therapy/standard of care in children with autism, as well as on their sleep habits and behaviour.

Our study aims to add to this growing body of evidence of the effect of air pollution on ASD in children.

• All Children with ASD aged 3-12 years attending pediatric neurology OPD and autism clinic will be screened for eligibility.

• Those children fulfilling the inclusion and exclusion criteria will be enrolled into the study.

• First group of children will be enrolled in the month of April 2025 and followed up for a period of 6 months during which the air pollution levels are lower (Average AQI <200) (April to September 2025), following which the primary assessment will be done in the end of September 2025 and then subsequently followed up again for another 6 months. At the end of 1 year, i.e. in the end of March 2026, they will undergo secondary assessment.

• Second group of children will be enrolled in the month of October 2025 and followed up for a period of 6 months during which the air pollution levels are higher (Average AQI >200) (October to March 2026), following which the primary assessment will be done in the end of March 2026 and then subsequently followed up again for another 6 months. At the end of 1 year, i.e. in the end of September 2026, they will undergo secondary assessment.

• Matching of both groups: Both the groups will be matched for all possible confounders

  1. Age
  2. Gender
  3. Socioeconomic status
  4. Household fuel
  5. Severity of autism
  6. Any smoker at home
  7. Cooking method used at home
  8. Overcrowding
  9. Use of AC/Cooler/Fan/Heater as appropriate
  10. BMI
  11. Other relevant clinical and medical details

• Bias: In order to avoid possible observer bias, the baseline assessment will be done and intervention module will be provided by the primary investigator. The follow up assessments at 6 and 12 months will be done by another DM senior resident from the division of child neurology.

Intervention and management of enrolled patients

• Informed consent will be taken from parents/legally acceptable representatives for the study
• Baseline demographic details and following evaluation will be done - Autism severity assessment using CARS -2 score Cognitive assessment using VABS/DP-3/MISIC Behavioural assessment using CBCL questionnaire Screening for sleep related disorders using CSHQ score Group I- Children with autism spectrum disorder followed up during the months with lower air pollution
• First group of children with autism spectrum disorder who meet the inclusion and exclusion criteria will be enrolled in the study after due informed consent in the month of April 2025.
• Their demographic details including place of residence will be collected at baseline.
• The children will also be evaluated for their baseline CARS score, DQ/SQ/IQ, sleep related disorders and behavioural issues using standardised validated tools as described above.
• The children will be followed up for a period of 6 months till September 2025 when they will be evaluated for primary outcome- CARS-2 score and other secondary outcomes-behavioural issues/sleep issues/cognitive ability.
• They will further be followed up for the next 6 months till March 2026 to be evaluated for secondary outcomes.
• At the end of 12 month follow up period, the children will again be evaluated for CARS-2 score, DQ/SQ/IQ, sleep related disorders and behavioural issues using standardised validated tools as described above.
• Data on exposure to air pollution (daily average PM 2.5 and PM 10 levels) will be collected for the total follow up period of 1 year based on the nearest air pollution monitoring site of CPCB.
• Those children identified with sleep issues in the CSHQ questionnaire will be managed as per the standard guidelines and will undergo actigraphy and polysomnography as and when warranted.
• In children with behaviour issues, standard of care will be provided in the form of anti-psychotic medications and other behavioural interventions.

Group II- Children with autism spectrum disorder followed up during the months with higher air pollution

• Second group of children with autism spectrum disorder who meet the inclusion and exclusion criteria will be enrolled in the study after due informed consent in the month of October 2025.
• Their demographic details including place of residence will be collected at baseline.
• The children will also be evaluated for their baseline CARS score, DQ/SQ/IQ, sleep related disorders and behavioural issues using standardised validated tools as described above.
• The children will be followed up for a period of 6 months till March 2026 when they will be evaluated for primary outcome- CARS-2 score and other secondary outcomes-behavioural issues/sleep issues/cognitive ability.
• They will further be followed up for the next 6 months till September 2026 to be evaluated for secondary outcomes.
• At the end of 12 month follow up period, the children will again be evaluated for CARS-2 score, DQ/SQ/IQ, sleep related disorders and behavioural issues using standardised validated tools as described above.
• Data on exposure to air pollution(daily average PM 2.5 and PM 10 levels)will be collected for the total follow up period of 1 year based on the nearest air pollution monitoring site of CPCB.
• Those children identified with sleep issues in the CSHQ questionnaire will be managed as per the standard guidelines and will undergo actigraphy and polysomnography as and when warranted.
• In children with behaviour issues, standard of care will be provided in the form of anti-psychotic medications and other behavioural interventions.

Blood Sample Analysis for Nuclear Chromatin To assess the gene expression changes due to air pollution, epigenetic mark on histone proteins, a core component of chromatin that needs to be closed or open state for transcriptional changes, can be measured. The H3 trimethylated at lysine 4 (H3K4me3) represents an open chromatin state representing active transcription. Chromatin immunoprecipitation using antibody detecting H3K4me3 followed by sequencing of the DNA fragments (ChIP-Seq) will determine active or poised transcription. Hence, the objective of the study is to perform ChIP-Seq analysis from peripheral blood samples to visualize the global change in transcription. Detection of transcriptional change would lead to further study to assess open vs. closed chromatin state. This will be determined by ATAC-Seq that detects chromatin states and subsequent RNA-Seq from same sample that determine RNA expression level as an indicator of transcription.

Three millilitres of blood sample will be collected from every 5th patient from each group, at the end of 6 months follow up, for the above analysis. Samples will be collected only from those patients who provide consent for the same. A total of 10 samples, 5 from each group will be collected and analysed.

Informed consent Eligible children will be enrolled only after receiving written informed consent from parents/guardian. Parents will be explained about the voluntary nature of participation in the study and the option to withdraw from the study at any point in time.

Ethical considerations Parents or LAR of the eligible children will be approached and explained regarding the study. Only those children whose parents/LAR give written informed consent will be enrolled in the study. The study protocol will be submitted to the AIIMS Institute Ethics Committee for approval and the study will be initiated only after such an approval is received.

Inclusion Criteria:1. Children aged 3- 12 years diagnosed with ASD according to DSM -V criteria and those who have received standard of care for less than 6 months at the time of screening and enrolment 2. Resident of Delhi-NCR

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Exclusion Criteria:

1. Other known secondary causes of ASD like Fragile-X Syndrome, Down Syndrome, Tuberous sclerosis, etc.

2. ASD with known metabolic disorders

3. ASD with drug refractory epilepsy

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Children with ASD based on DSM -V criteria between 3- 12 years of age attending the Pediatric Neurology OPD and Autism clinic, in Department of Pediatrics, at AIIMS, New Delhi