This is an observational study that aims to understand the effects of passive smoking (secondhand smoke exposure) on children's health and development. The main question the study seeks to answer is:

How does exposure to secondhand smoke affect the physical fitness, cognitive abilities, and academic performance of primary school children?

The study will compare two groups of children aged 6-11 years: one group exposed to secondhand smoke at home (due to parents or caregivers who smoke) and another group not exposed to secondhand smoke. The children's physical capacity, cognitive skills, and school performance will be assessed through various tests.

The goal of the study is to provide valuable insights into how secondhand smoke may negatively impact children, helping families, schools, and healthcare providers understand the risks and promote healthier, smoke-free environments for children.

This observational study aims to assess the effects of passive smoking on functional capacity, cognitive abilities, and academic performance in primary school children aged 6-11 years. The study will compare two groups: children exposed to secondhand smoke (passive smokers) and children not exposed (non-smokers).

Children in the passive smoking group have one or both parents who have been smoking for at least six years, with moderate to high levels of exposure based on a smoking index. These children will be compared with children in the non-smoking group who are not exposed to secondhand smoke at home or in other environments. The study will focus on three primary outcome areas:

• **Functional Capacity**: Measured by the 3-Minute Step Test to assess cardiorespiratory fitness and physical performance.
• **Cognitive Abilities**: Evaluated using the Wechsler Intelligence Scale for Children (WISC-V), which measures various cognitive functions, including verbal comprehension, working memory, and processing speed.
• **Academic Performance**: Assessed using the Academic Performance Rating Scale (APRS), which provides an evaluation of the child's academic success, attention, and classroom behavior.

This study will not involve any interventions, as it is observational in nature. Instead, it will collect data to identify differences in physical, cognitive, and academic outcomes based on passive smoking exposure. All data collection will occur at baseline, with the assessments conducted in a controlled, quiet environment to minimize distractions.

The sample will consist of 90 children (45 in each group), with participation based on inclusion and exclusion criteria. Children will be selected from primary schools in Cairo, Egypt, where parents have provided informed consent for participation. The study results will contribute valuable insights into the negative effects of secondhand smoke on children's health and development, which can guide health care providers, educators, and families in promoting smoke-free environments for children.

Inclusion Criteria:

1. Children aged 6-11 years, enrolled in primary school.
2. Both genders (male and female).
3. Healthy children with no musculoskeletal, visual, auditory, or cognitive impairments.
4. Children whose parents have been smoking for at least 6 years, with moderate to high smoking levels (based on the smoking index).
5. Children residing in a moderate socioeconomic status.
6. Children living in Cairo, Egypt.
7. Children who are able to follow simple commands and participate in assessments.

Exclusion Criteria:

1. Children with musculoskeletal problems, congenital deformities, visual or auditory defects, learning disabilities, or autism.
2. Children who are currently taking medications that affect alertness or cognitive function.
3. Children who are not exposed to secondhand smoke (non-smokers) but have parents who smoke at very low levels or do not meet the inclusion criteria for passive smoking exposure.
4. Children who are unable to cooperate or participate in the assessments.

The study population consists of 90 primary school children aged 6-11 years, selected from various primary schools in Cairo, Egypt. These children are categorized into two groups: 45 children exposed to secondhand smoke (passive smokers) and 45 children not exposed to secondhand smoke (non-smokers). All children are healthy and without any cognitive, visual, or musculoskeletal impairments. The children in the passive smokers group have parents who have been smoking for at least 6 years with moderate to high levels of smoking exposure. The non-smokers group consists of children who are not exposed to secondhand smoke at home or in their environments. The children's participation is voluntary, with informed consent obtained from parents or guardians.