A gas processing device such as an aerosol exposure monitor is configured for acquiring chronic data, acute data, or both simultaneously, and may include a pump and a noise dampening device. The noise dampening device may include an elastomeric membrane between an inlet chamber and an outlet chamber. In another aspect, an aerosol exposure monitor may include an impactor, a collection filter, and a nephelometer that includes a sample chamber integrated with an aerosol flow path associated with the impactor and collection filter.