Updated: Mar 24, 2022
Defining cab air quality - Starting with the end in mind
The debate regarding engineering control requirements for operator enclosures migrated from one committee meeting to another, and it did not matter whether it was SAE, ISO, EN, or ASABE. The focus was on cab filter efficiency, cab integrity, or cab pressure. Any one of these topics would generate a barrage of comments. However, we were unable to come to a consensus. Why was this so difficult? We had started without the "end in mind." In this case, the "end in mind" was the definition of acceptable operator enclosure air quality.
Acceptable air quality contains low concentrations of CO2, toxic gases, and respirable dust. If the appropriate level is quantified, the standards' writers can reach a consensus on the engineering control requirements to achieve these levels.
Acceptable levels for oxygen, toxic gases, and respirable dust are articulated in existing regulations and the ACGIH Guide to Occupational Exposure Values. Successful engineering or retrofitting can be validated by testing the completed cab's ability to provide compliant concentrations of CO2, toxic gas (when required), and respirable dust.
ISO 23875:2021 defines acceptable operator enclosure air quality and requires testing to validate that the operator enclosure produces acceptable air quality as a complete system.
A common refrain is that the air quality performance requirements differ from industry to industry. Does the agricultural machine operator produce a different level of CO2 than a mining machine operator? Does the dust generated in a warehouse or processing plant require a different filter than dust generated by plowing a field? Fortunately, all operator cabs function to protect the operator through a standard set of engineering controls, including a full cab enclosure, door and window seals, HVAC, cab pressure, intake and recirculation air filters. The differences in the various cabs are shape and size, which are dictated by the application.
The engineering requirements and the air quality they produce are universal. The operator's air quality requirements are also universal.
As an industry, we would be well served to find common agreement on the need to provide acceptable air quality based upon the definition given by the medical, industrial hygiene, and regulatory communities.
We hope to inform and provoke a conversation with our readers and learn what interests them.
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