Indoor air pollution has become a critical public health issue, particularly in low- and middle-income countries where households often have inadequate ventilation and rely on biomass or combustion sources for cooking and heating [1,6]. While outdoor air pollution has been widely studied, increasing evidence suggests that indoor environments can harbor even higher concentrations of harmful pollutants, particularly in densely populated or poorly ventilated dwellings [4]. In homes and schools, indoor air quality (IAQ) is compromised by particulate matter (PM₂.₅), carbon dioxide (CO₂), volatile organic compounds, and poor humidity control—conditions commonly found in both rural and urban settings [3,5].

Children are especially vulnerable to the adverse effects of indoor air pollution due to their developing respiratory systems, higher minute ventilation, and longer durations spent indoors compared to adults [1,6]. According to the World Health Organization (WHO), exposure to indoor pollutants is linked to increased risks of respiratory conditions such as asthma, bronchitis, wheezing, and impaired lung function, which may progress to chronic respiratory diseases later in life [1,4].

Although research has established connections between air pollution and child health, the majority of studies focus on outdoor pollutants, leaving a significant gap in understanding the impact of indoor air pollutants in domestic environments. Studies examining the correlation between real-time indoor air quality measurements and clinical respiratory outcomes in children remain limited, especially in resource-constrained or rural regions [2,5].

There is thus a pressing need for region-specific, data-driven investigations into the role of IAQ in shaping pediatric respiratory health. This study was designed to address this gap by evaluating indoor air pollutant levels and their association with respiratory symptoms in school-aged children residing in Velamavaripalle, Pulivendula.

This study aims to bridge this knowledge gap by evaluating indoor air quality parameters in urban households and investigating their association with respiratory symptoms among school-aged children. By identifying key environmental risk factors, this research seeks to inform targeted interventions for improving child health at the household level.

Study Design and Setting

A community-based cross-sectional study was conducted in Velamavaripalle, Pulivendula, located in the southern region of Andhra Pradesh, India. This rural setting was selected due to its typical residential construction styles and increasing concern over indoor air quality in enclosed household environments. The study was carried out over a period of 04  months, from October 2023 to January 2024.

Study Population

The study population comprised school-aged children between 6 and 12 years of age, residing in the selected community for at least six months prior to recruitment. Children who had a diagnosed chronic respiratory illness unrelated to environmental exposure (e.g., cystic fibrosis, congenital heart disease) were excluded from the study.

Sample Size and Sampling Technique

A sample size of 100 children was determined using estimates from previous literature assuming a 50% prevalence of respiratory symptoms, 95% confidence level, and 10% margin of error. A systematic random sampling method was employed to select eligible households from the community health worker registry.

Data Collection Tools and Procedure

Data collection consisted of two main components:

Indoor Air Quality (IAQ) Monitoring

Indoor air was assessed using portable, calibrated air quality monitoring instruments. The parameters measured included:

Particulate Matter (PM₂.₅) (μg/m³) using a laser-based sensor

Carbon Dioxide (CO₂) (ppm) using an NDIR sensor

Temperature (°C) and Relative Humidity (%) using digital thermo-hygrometers

Measurements were taken in the main living area during the morning and evening hours (8:00–10:00 AM and 6:00–8:00 PM) over two consecutive days and averaged for analysis.

Assessment of Respiratory Symptoms

A structured interviewer-administered questionnaire was used to collect data on demographics, housing characteristics, fuel type, ventilation status, and the presence of respiratory symptoms. Symptoms assessed included cough, wheezing, nasal congestion, and shortness of breath experienced over the past four weeks, as reported by the primary caregiver.

Ethical Considerations

The study was approved by the Institutional Ethics Committee, prior to data collection. Written informed consent was obtained from the parents or guardians of all participating children. Assent was also obtained from children aged above 7 years.

Statistical Analysis

Data were entered into Microsoft Excel and analyzed using SPSS version 26.0. Descriptive statistics were used to summarize baseline variables. Chi-square tests were used to examine associations between pollutant levels and respiratory symptoms. A multivariate logistic regression model was applied to identify independent predictors, adjusting for potential confounders including age, sex, household smoking, and use of biomass fuel. Statistical significance was set at p < 0.05.

A total of 100 school-aged children (aged 6–12 years) were enrolled in the study, with a near-equal distribution of males (n = 52; 52%) and females (n = 48; 48%). The mean age of participants was 9.1 ± 1.8 years.

Indoor Air Quality Parameters

Indoor air quality assessments revealed that the majority of households exceeded the World Health Organization (WHO) recommended limits for key pollutants. The mean concentration of PM₂.₅ was 48.2 ± 15.6 μg/m³, notably higher than the WHO limit of 25 μg/m³, with 78% of households exceeding the threshold. Carbon dioxide (CO₂) levels averaged 1125 ± 240 ppm, above the 1000 ppm limit in 62% of households. Similarly, relative humidity exceeded the optimal range (30–60%) in 55% of households, and indoor temperatures were above the recommended range (18–24°C) in 70% of cases (Table 1). These findings indicate that poor ventilation and indoor air quality were common across the surveyed households.

Table 1: Indoor Air Quality Parameters in Households (N=100)

PM₂.₅ and CO₂ levels exceeded WHO recommended limits in most households, indicating poor air quality.

Figure No:1.Indoor Air Quality Parameters vs WHO Limits (N=100)

Prevalence of Respiratory Symptoms

Out of 100 children, 61% reported experiencing at least one respiratory symptom in the past four weeks. The most frequently reported symptoms were nasal congestion (41%), cough (38%), wheezing (22%), and shortness of breath (19%) (Table 2).

Table 2: Prevalence of Respiratory Symptoms Among School-Aged Children (N=100)

Figure No:2.Prevalence of Respiratory Symptoms Among School-Aged Children

Association Between Indoor Air Quality and Respiratory Symptoms

A significant association was observed between elevated PM₂.₅ levels and the prevalence of respiratory symptoms. Among children exposed to PM₂.₅ concentrations above 25 μg/m³, 75% reported symptoms compared to 28% in those with lower exposure (χ² = 16.34, p < 0.001). Likewise, exposure to CO₂ levels exceeding 1000 ppm was associated with a higher incidence of wheezing and breathlessness (χ² = 6.12, p = 0.013). Although elevated humidity (>60%) showed a trend toward increased respiratory symptoms, this association did not reach statistical significance (χ² = 3.47, p = 0.062) (Table 3).

Table 3: Association Between Indoor Air Pollutants and Respiratory Symptoms

Statistically significant associations were observed for high PM₂.₅ and CO₂ levels, while high humidity showed a trend but was not significant.

Figure No:3.Association Between Indoor Air Pollutants and Respiratory Symptoms

Multivariate Logistic Regression Analysis

Multivariate logistic regression, adjusted for potential confounders including age, gender, household smoking, and biomass fuel use, confirmed the independent association of air pollutants with respiratory symptoms. Children exposed to high PM₂.₅ levels had 2.83 times higher odds of developing respiratory symptoms (OR = 2.83; 95% CI: 1.41–5.68; p = 0.003). Similarly, high CO₂ exposure was associated with increased odds (OR = 2.11; 95% CI: 1.02–4.37; p = 0.045) (Table 4).

Table 4: Multivariate Logistic Regression – Adjusted Odds of Respiratory Symptoms

Adjusted for age, gender, household smoking, and biomass fuel usage

This study investigated the association between indoor air quality and respiratory symptoms among school-aged children in Velamavaripalle, Pulivendula. The findings demonstrate a significant relationship between elevated levels of indoor air pollutants particularly PM₂.₅ and CO₂ and the prevalence of respiratory symptoms in children. These results contribute to the growing body of evidence that indoor environmental exposures play a critical role in pediatric respiratory health, especially in rural and semi-urban settings.

In our study, 78% of households had PM₂.₅ levels exceeding the WHO recommended limit of 25 μg/m³, and 62% exceeded the CO₂ threshold of 1000 ppm, indicating poor ventilation. These findings are consistent with previous research. Rawi et al. [7] found that elevated PM₂.₅ levels were significantly associated with reduced lung function in Malay preschool children. Similarly, Choo and Jalaludin [12] reported that Malaysian school-aged children exposed to poor indoor air quality experienced more frequent respiratory symptoms, particularly in settings with high particulate concentrations.

The prevalence of at least one respiratory symptom in our study was 61%, with nasal congestion (41%) and cough (38%) being the most common. This aligns with findings by Siwarom et al. [11], who observed that respiratory symptoms such as cough, wheezing, and phlegm were significantly more common among children exposed to indoor pollution in Thai preschools. Santri et al. [8] also noted a significant correlation between exposure to indoor pollutants and acute respiratory infection symptoms in children under five in Indonesia.

Significant associations were observed between high PM₂.₅ exposure and respiratory symptoms (χ² = 16.34, p < 0.001), and between elevated CO₂ and symptoms like wheezing and breathlessness (χ² = 6.12, p = 0.013). These relationships remained significant in multivariate analysis, with odds ratios of 2.83 and 2.11, respectively. Breysse et al. [9] similarly reported that indoor particulate pollution was a strong determinant of asthma exacerbation in children. In a more vulnerable population, Rice et al. [10] found that indoor air pollution sources significantly contributed to respiratory symptoms among children with bronchopulmonary dysplasia.

While relative humidity (>60%) was not statistically significant (p = 0.062), it showed a positive trend with respiratory symptoms. High humidity may facilitate mold growth and enhance allergen bioactivity, as supported by findings from Reponen et al. and also discussed in a recent multicenter study by Rice et al. [13], which highlighted the contribution of parental reports of indoor air pollution to increased respiratory morbidity in children with pre-existing conditions.

Our results are also supported by the cross-sectional study conducted by Nandasena et al. [14] in Sri Lanka, which showed higher rates of respiratory symptoms among children residing in areas with greater air pollution exposure, particularly in poorly ventilated homes.

The strengths of our study include the objective measurement of air quality parameters in home environments and adjustment for confounding variables such as smoking and fuel type. However, the cross-sectional design limits causal inference, and the reliance on caregiver-reported symptoms may introduce recall bias. Furthermore, the two-day air sampling period may not reflect long-term or seasonal variations in indoor air quality.

Despite these limitations, the findings have strong public health relevance. They emphasize the need for urgent interventions such as promoting cleaner cooking technologies, improving household ventilation, and integrating indoor air quality monitoring into community health programs. School-based respiratory health surveillance and parental education can also serve as effective preventive measures to reduce the respiratory disease burden in children.

This study highlights a clear association between poor indoor air quality and respiratory symptoms among school-aged children in Velamavaripalle, Pulivendula. Elevated levels of PM₂.₅ and CO₂ were significantly linked to increased occurrences of cough, nasal congestion, wheezing, and breathlessness. Multivariate analysis confirmed that children exposed to these pollutants had higher odds of developing respiratory symptoms, independent of household smoking or fuel type. These findings underscore the urgent need for public health interventions aimed at improving indoor air quality through better ventilation, cleaner cooking practices, and awareness programs. Protecting children from indoor air pollutants is essential to reducing respiratory illness and promoting healthier developmental outcomes.

1. Aithal SS, Sachdeva I, Kurmi OP. Air quality and respiratory health in children. Breathe (Sheff). 2023 Jun;19(2):230040. doi: 10.1183/20734735.0040-2023. Epub 2023 Jun 13. PMID: 37377853; PMCID: PMC10292770.
2. Azam NSA, Jalaludin J, Suhaimi NF. The association between indoor air quality and respiratory health symptoms among preschool children in Penang, Malaysia. Int J Environ Health Res. 2024 Jun 11:1-14. doi: 10.1080/09603123.2024.2365308. Epub ahead of print. PMID: 38860645.
3. Fsadni P, Bezzina F, Fsadni C, Montefort S. Impact of School Air Quality on Children's Respiratory Health. Indian J Occup Environ Med. 2018 Sep-Dec;22(3):156-162. doi: 10.4103/ijoem.IJOEM_95_18. PMID: 30647518; PMCID: PMC6309359.
4. Holden KA, Lee AR, Hawcutt DB, Sinha IP. The impact of poor housing and indoor air quality on respiratory health in children. Breathe (Sheff). 2023 Jun;19(2):230058. doi: 10.1183/20734735.0058-2023. Epub 2023 Aug 15. PMID: 37645022; PMCID: PMC10461733.
5. Madureira J, Paciência I, Ramos E, Barros H, Pereira C, Teixeira JP, Fernandes Ede O. Children's Health and Indoor Air Quality in Primary Schools and Homes in Portugal-Study Design. J Toxicol Environ Health A. 2015;78(13-14):915-30. doi: 10.1080/15287394.2015.1048926. PMID: 26167757.
6. Raju S, Siddharthan T, McCormack MC. Indoor Air Pollution and Respiratory Health. Clin Chest Med. 2020 Dec;41(4):825-843. doi: 10.1016/j.ccm.2020.08.014. PMID: 33153698; PMCID: PMC7665158.
7. Rawi NA, Jalaludin J, Chua PC. Indoor Air Quality and Respiratory Health among Malay Preschool Children in Selangor. Biomed Res Int. 2015;2015:248178. doi: 10.1155/2015/248178. Epub 2015 Apr 23. PMID: 25984527; PMCID: PMC4423007.
8. Santri IN, Wardani Y, Phiri YVA, Nyam G, Putri TA, Isni K, Suryani D, Sambo G. Associations Between Indoor Air Pollutants and Risk Factors for Acute Respiratory Infection Symptoms in Children Under 5: An Analysis of Data From the Indonesia Demographic Health Survey. J Prev Med Public Health. 2023 May;56(3):255-263. doi: 10.3961/jpmph.22.470. Epub 2023 Apr 18. PMID: 37287203; PMCID: PMC10248105.
9. Breysse PN, Diette GB, Matsui EC, Butz AM, Hansel NN, McCormack MC. Indoor air pollution and asthma in children. Proc Am Thorac Soc. 2010 May;7(2):102-6. doi: 10.1513/pats.200908-083RM. PMID: 20427579; PMCID: PMC3266016.
10. Rice JL, McGrath-Morrow SA, Collaco JM. Indoor Air Pollution Sources and Respiratory Symptoms in Bronchopulmonary Dysplasia. J Pediatr. 2020 Jul;222:85-90.e2. doi: 10.1016/j.jpeds.2020.03.010. Epub 2020 May 13. PMID: 32417083; PMCID: PMC7321913.
11. Siwarom S, Puranitee P, Plitponkarnpim A, Manuyakorn W, Sinitkul R, Arj-Ong Vallipakorn S. Association of indoor air quality and preschool children's respiratory symptoms. Asian Pac J Allergy Immunol. 2017 Sep;35(3):119-126. doi: 10.12932/AP0838. PMID: 27996287.
12. Choo CP, Jalaludin J. An overview of indoor air quality and its impact on respiratory health among Malaysian school-aged children. Rev Environ Health. 2015;30(1):9-18. doi: 10.1515/reveh-2014-0065. PMID: 25411980.
13. Rice JL, Collaco JM, Tracy MC, Sheils CA, Rhein LM, Popova AP, et al. Parental Report of Indoor Air Pollution Is Associated with Respiratory Morbidities in Bronchopulmonary Dysplasia. J Pediatr. 2024 Dec;275:114241. doi: 10.1016/j.jpeds.2024.114241. Epub 2024 Aug 14. PMID: 39151604; PMCID: PMC11560483.
14. Nandasena S, Wickremasinghe AR, Sathiakumar N. Respiratory health status of children from two different air pollution exposure settings of Sri Lanka: a cross-sectional study. Am J Ind Med. 2012 Dec;55(12):1137-45. doi: 10.1002/ajim.22020. Epub 2012 Feb 1. PMID: 22298308; PMCID: PMC3432736.