The assessment of droplets in the exhaled air of mild asthma patients indicated changes in surfactant protein-A and albumin after exposure to indoor ultrafine particles derived from cooking. Candle and cooking exposure are associated with mild inflammation.
Personal exposure and health outcomes depend on exposure to indoor pollutants, including particulate matter from burning candles and cooking. Several studies have reported the association between exposure to ultrafine particles and metabolic changes; however, there is limited evidence pertaining to systemic health outcomes.
This study investigated the inflammatory changes in mild asthma patients following short-term exposure to ultrafine particles from candles and cooking. The findings are published in the journal Particle and Fibre Toxicology.
The randomized controlled trial included a total of 36 non-smoking individuals with mild asthma who attended three exposure sessions. These included clean, filtered air, air mixed with cooking emissions, and air mixed with candle emissions.
Particle Exposure During Cooking and Burning Candles
The levels of relative humidity and temperature were kept normal across the exposures. The levels of carbon dioxide (CO2) and nitrogen dioxide (NO2) increased during cooking and candle exposure compared to clean air exposure. The particle mode diameter was greater during cooking exposure compared to candle exposure (88 ± 20 nm versus 8 ± 1 nm).
During candle exposure, levels of CO2 increased to 915 (±66) ppm, and NO2 increased to 52.9 (±1.8) ppb compared to CO2: 629 (±74) and NO2: 2.1 (±0.5) during clean air exposure. During cooking, levels of CO2 and NO2 were 542 (±43) ppm and 6.5 (±1.8) ppb, respectively
Levels of Polycyclic Aromatic Hydrocarbon
The average levels of polycyclic aromatic hydrocarbons (PAHs) in clean air, cooking, and candle burning were 1.0 ng/m3, 1.1 ng/m3, and 10 ng/m3, respectively. Hence, PAHs are derived from both cooking and candle burning.
Airway Biomarkers of Exposure to Ultrafine Particles
While the levels of surfactant protein-A (SP-A) remained stable in exhaled air droplets during candle exposure, the levels of SP-A decreased during clean air and cooking exposure. The albumin content in exhaled air droplets increased during exposure to burning candles and cooking compared to clean air. Interleukin (IL)-1ß decreased following exposure to cooking.
Systemic Biomarkers of Exposure to Ultrafine Particles
Compared to exposure to clean air, exposure to burning candles and cooking were associated with decreases in tumor necrosis factor (TNF)-α and IL-1ß levels. There was a significant increase in C-C motif chemokine ligand 2 (CCL2) following candle exposure. The C-reactive protein (CRP) levels remained stable following exposure to particles in cooking and burning candles. Gene expression related to DNA repair and pro-inflammatory responses in peripheral blood mononuclear cells and endothelial progenitor cells did not vary significantly with exposures.
Laursen, K. R., Christensen, N. V., Mulder, F. a. A., Schullehner, J., Hoffmann, H. J., Jensen, A. A., Möller, P., Loft, S., Olin, A., Rasmussen, B. S., Rosati, B., Strandberg, B., Glasius, M., Bilde, M., & Sigsgaard, T. (2023). Airway and systemic biomarkers of health effects after short-term exposure to indoor ultrafine particles from cooking and candles – A randomized controlled double-blind crossover study among mild asthmatic subjects. Particle and Fibre Toxicology, 20(1). https://doi.org/10.1186/s12989-023-00537-7