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Five (Perhaps Surprising) Places Diesel Fumes Can Quickly Accumulate

Industry Insights

When diesel exhaust can't disperse naturally, hazardous contaminants can build up quickly, creating a risk for workers and anyone nearby.

Diesel-powered equipment is a staple across construction, infrastructure, aviation, warehousing and industrial sites, and while most people understand that diesel exhaust needs to be managed, many underestimate just how easily diesel fumes can become trapped in certain environments.

Here are five locations where diesel fumes commonly become trapped – and why they often catch project teams by surprise.

1. Basement Ramps and Underground Car Parks

At first glance, a basement ramp may appear relatively open. After all, one end usually leads outdoors.

The problem is that diesel exhaust doesn't simply travel in a straight line out of the opening.

As vehicles enter and exit underground spaces, diesel particulate matter (DPM), carbon monoxide, nitrogen oxides and other contaminants can accumulate in low-airflow areas. Ramps, corners and vehicle waiting zones often become pockets where fumes linger far longer than expected.

This can be particularly problematic during peak activity periods when multiple vehicles are entering and leaving the space throughout the day.

Why fumes get trapped:

• Limited natural airflow
• Long travel paths to fresh air
• Multiple vehicles operating in the same area
• Exhaust recirculation within enclosed spaces

2. Loading Docks

Loading docks often appear well ventilated because large roller doors remain open for significant periods of time.

However, loading docks frequently experience what's known as "dead air zones" where air movement is minimal – despite the presence of open doorways.

Delivery vehicles may spend extended periods idling while unloading goods, creating a concentrated source of diesel exhaust. Depending on wind direction and building design, those fumes can become trapped beneath awnings, within recessed dock areas or inside adjoining warehouse spaces.

Workers moving between trucks and buildings may unknowingly spend hours exposed to elevated diesel exhaust concentrations.

Why fumes get trapped:

• Vehicles idling during loading and unloading
• Building structures disrupting airflow
• Exhaust accumulating under canopies and awnings
• Air being drawn into nearby work areas

3. Airport Hangars

Airport hangars are among the largest enclosed spaces many workers will encounter. Yet their sheer size can create a false sense of security when it comes to diesel exhaust exposure.

Ground support equipment, tugs, generators and maintenance vehicles frequently operate inside or around hangars. While hangar doors may remain open, the internal volume of these structures often creates areas where air movement is surprisingly poor.

Without effective ventilation strategies, harmful diesel exhaust can remain suspended within the workspace and accumulate around maintenance crews, contractors and support personnel.

Why fumes get trapped:

• Large enclosed volumes with inconsistent airflow
• Multiple diesel-powered vehicles operating simultaneously
• Air movement concentrated near doors while interior areas remain stagnant
• Exhaust generated close to workers

4. Tunnels

Few environments highlight the importance of diesel exhaust management more than tunnels.

Whether it's road construction, rail infrastructure, utility installation or maintenance works, tunnels present a unique challenge because there are often very limited pathways for contaminated air to escape.

Even relatively small diesel-powered equipment can generate significant concentrations of exhaust emissions when operating within a tunnel environment.

Without properly designed ventilation systems, contaminants can build up rapidly, reducing visibility and increasing worker exposure.

Why fumes get trapped:

• Restricted airflow pathways
• Long distances between fresh air sources
• Continuous operation of diesel-powered equipment
• Limited opportunities for natural ventilation

5. Temporary Site Sheds and Enclosures

One of the most overlooked diesel exhaust risks occurs in temporary work areas.

Site sheds, temporary enclosures, acoustic barriers and weather protection structures are often installed to improve comfort, reduce noise or protect workers from environmental conditions.

However, these structures can unintentionally restrict airflow and create conditions where diesel fumes accumulate.

A generator positioned outside a shed, a nearby delivery vehicle or diesel-powered plant operating adjacent to the enclosure can all contribute to exhaust entering and becoming trapped within the space.

Because these areas are temporary, ventilation requirements are sometimes overlooked during project planning.

Why fumes get trapped:

• Reduced natural ventilation
• Temporary structures altering airflow patterns
• Nearby diesel-powered equipment
• Limited consideration of air exchange requirements

The Common Factor? Poor Air Movement

While these environments may appear very different, they share one common characteristic: limited or unpredictable airflow.

Also, diesel exhaust exposure isn't always obvious. In many cases, workers become accustomed to the smell of diesel or assume that an open doorway provides sufficient ventilation.

The reality is that hazardous diesel particulate matter can remain airborne long after visible exhaust has disappeared.

As workplace exposure requirements continue to evolve – come December 1, 2026 the Workplace Exposure Limit (note also the change from naming convention of ‘Workplace Exposure Standard’) will decrease significantly from 0.1% mg/m³ to 0.01% mg/m³ over an 8-hour time weighted average – and awareness of diesel particulate matter increases, project teams need to place greater focus on engineering controls that capture, extract or dilute contaminated air before it reaches workers.

Managing Diesel Exhaust Exposure

Effective diesel exhaust management typically involves a combination of:

• Source capture systems
• Diesel particulate filtration
• Local exhaust ventilation
• Mechanical ventilation
• Air quality monitoring
• Operational planning and equipment selection

Every site is different, but identifying locations where diesel fumes are likely to become trapped is the first step towards reducing exposure.

Need help managing diesel fumes on your site?

RVT Group provides temporary ventilation, diesel exhaust filtration and air quality monitoring solutions for challenging work environments. Our team can help identify potential diesel exhaust exposure risks and recommend practical engineering controls to protect workers and maintain site productivity.