Newly certified HVAC and refrigeration technicians are facing a more diverse job market than ever before.

Ongoing technological breakthroughs in the heating, cooling, and refrigeration industries have created the need for many workers knowledgeable in the latest technologies to repair, upgrade, and replace equipment.

Refrigeration, especially, is a widespread industry with countless applications, from industrial metals processing to the prevention of food-borne illnesses at small sidewalk cafes.

With stringent food regulation standards, including refrigeration mandates in place at the federal level, it's no wonder that the food and beverage industries - from processing to serving - seem to be safer than ever.

However, food processing and preparation were not always so safe.

Thank the advent of widespread, affordable, refrigeration technologies - and a breakthrough polemic novel by muckraker Upton Sinclair.

The Jungle is a difficult, heart-stopping read. It is narrated through the eyes of the story's protagonist, Lithuanian immigrant Jurgis Rudkus, who eventually protests the conditions of the meat plant at which he once worked.

The novel describes the disastrous conditions present in the meat-packing plants of Chicago, where rodents were ground up with beef, and hoofs and entrails were swept from the floor and sold to human beings as potted meat.

The working conditions the men faced were just as grim, some losing body parts - or, their lives - to the meat-packing plants. 

Sinclair's groundbreaking 1906 novel alerted then-president Theodore Roosevelt to the dangers the meat factories of Chicago presented to the workers, and to any American eating tainted meat.

The Food and Drug Administration, a commercial freezer federal agency overseeing the safe production and distribution of foodstuffs, was swiftly established under Roosevelt, along with stringent federal regulations for meat processing.

In addition, the Pure Food and Drug Act was passed into law in June 1906.

This act established guidelines for federal inspection of meat products, making the unsanitary meat production conditions described in The Jungle unlawful.

Though the meat-packing plants of Chicago had adopted refrigeration technologies by the beginning of the 20th century, the meat that left those factories was of poor quality, and often, riddled with food-borne microbes.

Sinclair's novel - as well as the writings and journalistic efforts of other "muckrakers," or researchers who expose unjust conditions in society - helped to raise collective American awareness about the importance of healthy, refrigerated meat. 

After The Jungle stirred American ire and introduced sweeping food-processing reforms into legislation, the importance of good, sanitary food production and preparation techniques fairly exploded in popularity around the nation.

Refrigeration was recognized as an effective means of retarding food spoilage by storing food at temperatures lower than harmful bacteria can colonize and breed.