Air Fresheners

BACKGROUND. Clean-air legislation has been around for years. Prior to 1955, cities, counties and states all carried air-quality laws on the books. The Air Pollution Control Act of 1955 turned air-quality regulation into a federal matter. In the 1960s, U.S. regulations established standards for automobile emissions.

The basis for today’s rules and regulations is the Clean Air Act of 1990. The first tier of emission regulations for off-road diesel engines arrived in 1994. Subsequent tiers define increasingly tighter emissions requirements for these engines.

Internal combustion engines produce four major emissions: nitrogen oxides (NOx), particulate matter (PM), hydrocarbons and carbon monoxide. For diesel engines, the regulatory focus is on NOx and PM.

Both the U.S. Environmental Protection Agency and the European Union (EU) implemented two separate standards—one for on-highway truck engines, another for off-road use—regulating emissions.

The off-road standards are being phased in over a number of years, gradually reducing the legal levels of emissions for various sizes of diesel engines. In the United States, these phases are identified as "Tiers" (Tier 1 – Tier 4). In the EU, they are identified as "Stages" (Stage I – Stage IIIB). In time, the differences between on-highway and off-road standards will narrow, and the two sets of standards will converge.

The EPA estimates that by 2010, Tier 3 standards will reduce NOx emissions from diesel engines by about 1 million tons per year, an effect similar to taking 35 million passenger cars off the road.

Tier 4 standards are even more stringent, reducing NOx emissions by 90 percent beyond Tier 3 regulations.

Manufacturers met Tier 1 levels through relatively minor engine modifications, including changes in fuel rates, timing and compression. Air-to-air aftercoolers and turbos made Tier 2 engines visually distinct from earlier engines. But Tier 3 requirements forced manufacturers to take a big leap in engine development. That was when Caterpillar introduced engines with ACERT technology.

The core concept behind ACERT technology is advanced combustion. The combustion process is carefully controlled to reduce pollutant levels, while maintaining performance and efficiency.

Other companies introduced engines with various forms of exhaust gas recirculation (EGR), a process that returns exhaust gases to the combustion chamber.

To meet Tier 4 requirements, Caterpillar is focused on deep machine integration, electronic controls and aftertreatment. Other manufacturers will also need to make changes to reach Tier 4 goals.

VARIED REGULATIONS. Emissions regulations vary throughout the world, which introduces a layer of complexity to moving machines across borders. Certification labels must be attached to diesel engines before they are allowed into the United States. Customs officials inspect off-road equipment at the port of entry and will not allow machines without labels that correspond to the tier level in place at time of manufacture. These labels must remain on the engine and they must be easily visible in case of inspection. These labels must also be in place in order for a piece of equipment to be resold.

That means recyclers won’t be able to import new machines originally sold outside the United States without an EPA label. They will, however, be able to import used machines that do have the label.

NON-ATTAINMENT ZONES: The EPA has designated more than 470 counties as non-attainment areas in the United States. A non-attainment area is identified as a location where air pollution levels persistently have exceeded national air quality standards established by the Clean Air Act. State and local governments that used to set their own standards are now planning to meet the federal standards.