Diesel and Air Quality
How will the diesel generator used in the UV pilot program affect air quality?
The generator being used for the pilot program meets Tier 4 emission standards, established by the Environmental Protection Agency (EPA). These emission standards aim to reduce harmful emissions from nonroad diesel engines, specifically particulate matter (PM) and nitrogen oxides (NOx), by requiring new engines to use advanced emission control technologies and mandating sulfur reductions in diesel fuel.
Based on the available data provided by the EPA, the use of a Tier 4-compliant generator, its temporary use over a 3-month period, and placement over 50 feet from the nearest home, we don’t expect there to be any significant air quality or health impacts.
How far is the generator from residential homes?
Typical manufacturer guidance recommends a 0–20 foot buffer between generators and buildings. We have exceeded this by placing the generator over 50 feet away from the nearest residential area. This distance, combined with the generator’s cleaner emissions, further reduces any potential exposure for residents.
Is this generator installation permanent?
No. The generator is in use temporarily, for the limited 3-month duration of the UV pilot program. Once the pilot is complete, the generator will be removed.
Will residents be affected by the diesel exhaust from the generator?
No impact is expected. The combination of advanced emission controls, distance from homes, and temporary installation make the risk of health or air quality impacts extremely low. While only a formal study could provide site-specific data, all existing evidence and guidance indicates that the generator’s use during this short pilot will not negatively affect nearby residents.
What are Tier 4 Emission Standards and why do they matter?
Tier 4 standards were established by the EPA to reduce harmful emissions—specifically particulate matter (PM) and nitrogen oxides (NOx)—from non-road diesel engines, including those used in both construction and industrial applications.
These standards are supported and enforced in several states, often referred to as “CARB” states, which include California and Massachusetts. CARB stands for California Air Resources Board and has been used in this FAQ to guide our responses to residents regarding diesel-related health concerns.
Quick Facts about Tier 4 Emission Standards:
- These standards apply to new engines used in heavy equipment and off-road machinery, including those used in industries like mining, construction, and agriculture.
- New Source Performance Standards (NSPS) are an emissions regulation in large stationary generator sets that assist in the steady rate of air quality improvement.
- Tier 4 requirements only apply to new products and not to existing machines or equipment
- NOx contributes to the formation of ground-level ozone, which can be harmful to human health.
- PM exposure has been shown to have adverse health effects, particularly on the respiratory system.
- By reducing these pollutants, Tier 4 standards help improve air quality and protect public health.
How are Tier 4 Standards Achieved?
- Engine manufacturers are required to produce new engines with advanced emission control technologies to meet Tier 4 standards.
- These technologies include things like fuel injection systems, exhaust gas recirculation, and particulate filters.
- The EPA has also adopted requirements for in-use diesel fuel to decrease sulfur levels by more than 99 percent, as sulfur can damage emission control devices