What type of contaminants were John Boyd Dunlop's 19th-century air purifier mechanisms primarily intended to capture?

Relatively large, visible contaminants like smoke soot

The conceptual goal of early 19th-century mechanical air purifiers, such as Dunlop's water-based device from 1879, was rooted in mitigating immediate, visible environmental degradation. These devices focused on capturing particulate matter that was large enough to be easily seen, such as smoke residue and soot that resulted from widespread coal or wood burning in urban centers. This focus contrasts sharply with modern air purification concerns, which center on invisible threats like fine dust, allergens, bacteria, and viral carriers that measure far smaller than 0.3 microns. The earlier devices were effective for gross particulate removal but lacked the sophistication to address threats at the microscopic level.