Understanding the impact of dust deposition and CO ₂ level on biofilm development causing biodeterioration of historic buildings and monuments in India

The deterioration of buildings and historic monuments due to phototrophic biofilms, dust, and carbon dioxide concentration is an increasingly significant global issue, but remains insufficiently studied. In this research, phototrophic biofilms were collected from nine sampling sites, which were categorized as control, moderately contaminated, and severely contaminated based on the air quality index and canopy cover. Severely contaminated sites showed higher temperatures, CO₂ levels, and dust accumulation, but lower humidity. Cyanobacteria dominated all biofilm samples, followed by fungal hyphae and spores. Green algae and diatoms contributed minimally. Healthy diatom frustules decreased sharply with increasing contamination, from the control sites to severely contaminated sites. Regression analysis revealed significant positive correlations between cyanobacterial abundance and both CO₂ levels and dust deposition, indicating that increased air pollutants promote the growth of cyanobacteria and diatoms in phototrophic biofilms, further highlighting their potential as a sensitive bioindicator of environmental contamination affecting cultural heritage sites.