Abstract
Environmental noise and air pollutants may share emission sources, but their temporal association can vary among urban settings. This exploratory study examined noise, carbon monoxide (CO), PM₂.₅ and PM₁₀ at residential, industrial and airport locations in Selangor, Malaysia, during a monitoring campaign spanning November 2025 to March 2026. One AirSync unit per site recorded measurements at one-minute intervals using factory-calibrated PM, CO and noise sensing components. Hourly median data were summarised using Spearman rank correlations, alongside descriptive temporal profiles and daily particulate concentration comparisons. Noise–pollutant associations were weak at all sites (|ρ| ≤ 0.246). The largest coefficient was for CO and noise at the airport (ρ = 0.246). PM₂.₅ and PM₁₀ outputs were strongly coupled (ρ ≥ 0.999). At the industrial site, sensor-derived daily means exceeded the numerical Malaysian 24-hour thresholds on 99 of 127 valid days for PM₂.₅ and 84 of 127 days for PM₁₀. These findings provide limited support for a simple contemporaneous noise-only indicator under the conditions examined. Interpretation remains constrained by one site per category, measurement uncertainty, discrete CO outputs and the absence of time-series-adjusted inference or independent predictive validation.