Field performance evaluation during fog-dominated wintertime of a newly developed denuder-equipped PM1 sampler

This study presents the performance evaluation of a novel denuder-equipped PM₁ (particles having aerodynamic diameter less than 1 μm) sampler, tested during fog-dominated wintertime, in the city of Kanpur, India. One PM₁ sampler and one denuder-equipped PM₁ sampler were co-located to collect ambient PM₁ for 25 days. The mean PM₁ mass concentration measured on foggy days with the PM₁ sampler and the denuder-equipped PM₁ sampler was found to be 165.95 and 135.48 μg/m³, respectively. The mean PM₁ mass concentration measured on clear days with the PM₁ sampler and the denuder-equipped PM₁ sampler was observed to be 159.66 and 125.14 μg/m³, respectively. The mass concentration with denuder-fitted PM₁ sampler for both foggy and clear days was always found less than the PM₁ sampler. The same drift was observed in the concentrations of water-soluble ions and water-soluble organic carbon (WSOC). Moreover, it was observed that the use of denuder leads to a significant reduction in the PM positive artifact. The difference in the concentration of chemical species obtained by two samplers indicates that the PM₁ sampler without denuder had overestimated the concentrations of chemical species in a worst-case scenario by almost 40 %. Denuder-fitted PM₁ sampler can serve as a useful sampling tool in estimating the true values for nitrate, ammonium, potassium, sodium and WSOC present in the ambient PM.