A Fresh Air Mix

Breathe easy with new standards for fresh air equipment.

Several years ago, I helped remove a large machine shed that had been gutted by fire. Although severely weakened, most of the wood frame had been left standing. Inside, the concrete floor was covered with a mixture of fiberglass insulation, ash, charcoal and the remnants of various chemical or plastics that had burned and melted into an ugly mess. After salvaging the few items that had not been destroyed, we cut the charred posts and beams and pulled the structure to the ground.

The work I did on foot was always done while wearing a respirator mask and eye protection. The mask, as well as my exposed face, was soon covered in black grit. The pair of filters were changed once over the week-long job. The respirator was mandatory when I was on the ground. Today, I wonder why I would remove the mask before I crawled into the skid steer to load the debris into a Dumpster. The skid steer, a model from the late 1980s with open sides, gave little protection from fine black grit; it settled inside the cab. Great clouds would be set drifting after each scoop from inside the building, but the respirator was allowed to take a break. I felt safe inside the machine, as if I had walked into another room and shut the door.

In the evolution of the cab used on machines ranging from agricultural to quarry equipment, being able to shut a door was a major development. As the operator's working conditions have commanded more attention, much of the work has been focused on the operator's comfort and safety. During this movement the quality of the air inside that cab has been an afterthought. Once doors and windows were included, it was enough to provide an HVAC system, or at least V (ventilation). The quality of the air that was being piped into the cab wasn't a big concern. That's changing, as the cover story illustrates. Today it's possible to crawl into the safety of a pressurized and filtered cab in machines ranging from sophisticated crop sprayers to the very descendents of the skid steer brand I used in that burned-out building.
Sophisticated air cleaners are being developed for dozers used in wildfires. Firefighting dozers have been called into duty a few times this year, most recently in California. According to the U.S. Forest Service, the October wildfires there destroyed 2,000 homes, forced the evacuation of more than 1 million residents and resulted in seven fatalities.
This focus on air quality in the relatively tight confines of the cab isn't a surprise. The air that gets pulled into engine and cab precleaners is being overhauled at the same time.

Even as those foundations in California smoldered and skid steers were hauled in to help with the cleanup, scientists were looking at what the massive fires were doing to the atmosphere. According to recently published research by scientists at the National Center for Atmospheric Research (NCAR) and the University of Colorado at Boulder, CO, large-scale fires in western and southeastern states can pump as much carbon dioxide into the atmosphere in a few weeks as California's entire motor vehicle traffic in a year.

The study estimates that U.S. fires release about 290 million metric tons of carbon dioxide a year, the equivalent of 4 to 6% of the nation's carbon dioxide emissions from fossil fuel burning.