Indoor air quality and its impacts on asthma and COPD

Background: Though indoor air pollution is associated with high mortality and economic impact globally, it is relatively understudied. Knowledge gaps remain regarding exposure to peak pollutant concentrations and their effects, especially among patients with respiratory diseases who are susceptible to a greater impact.

Methods: This 2-week cohort study monitored indoor air quality and symptoms in patients with asthma and chronic obstructive pulmonary disease. Statistical process control charts were used to track hourly pollutant peaks, while notched box plots visualised significant particulate matter 2.5 (PM_2.5) peaks over 6-hour periods. Linear mixed-effects and autoregressive models were used to assess the impact of PM_2.5 on symptoms.

Results: The analyses included 30 participants. Hourly plots revealed that 43.3% experienced PM_2.5 and PM₁ peaks above the upper control limit between 6 pm and 9 pm, with 33.3% occurring specifically at 19:00 hours, consistent with cooking as a source of particulates. There were also a few peaks between 10 am and 12 noon. Peaks recorded between midnight and 5 am were minimal, corresponding to low activity during sleep. Smokers exhibited higher average pollutant levels than non-smokers. On average, participants experienced four to six pollutant peak periods exceeding the WHO 2021 air quality guidelines. No statistically significant association was found between PM_2.5 and asthma symptoms (p>0.05), although a weak relationship was observed visually.

Conclusion: The data suggest that human activities significantly influence indoor air quality for PM, indicating that behavioural interventions could help optimise it.