When both particulates and gases/vapors toxic by inhalation are anticipated to be in your breathing zone during handling, the pesticide label will specify respirators with both a chemical purifying element and a particulate filter.
Combo cartridges for non-powered air-purifying respirators can have either N, R, or P rated filters. Combination chemical cartridges for powered air-purifying respirators will include an HE filter; while a combo gas mask canister would typically include a P100 filter. These filters are permanently attached to cartridges or canisters.
Another option would be the use of particulate N, R, or P filters “piggy-backed” onto the chemical cartridge(s) of a non-powered APR using a retainer (see figure to left).
Apply individual filter and chemical cartridge replacement criteria to respirators fitted with combination purifying elements. For example, if using a respirator with a combo OV/N95 cartridge and you detected breakthrough in the mask, the entire cartridge would need replacement. Or if using a respirator with an OV cartridge piggybacked with an N95 filter and it became uncomfortable to breathe, you would keep the cartridge but replace the filter with a new one.
Source: Respiratory Protection for Occupational Users of Pesticides. Patricia D. Hastings, Coordinator, Rutgers Pesticide Safety Education Program.