Clearing the air

by Karen Bowen

Over the summer, it’s great to take advantage of air-conditioning to maintain a reasonable temperature in your rig. However, driving long hours with your windows closed may seriously reduce your cab’s air quality and affect your health.

Although your unit’s heating, ventilation and air-conditioning (HVAC) system keeps you cool, it also allows a variety of pollutants into your cab. Independent studies show that concentrations of toxic gases, such as carbon monoxide, hydrocarbons, volatile organic compounds (VOCs), and oxides of nitrogen are often higher in vehicles than allowed by the World Health Organization (WHO) and the Occupational Safety and Health Administration (OSHA).

These gases come from many sources. One is vehicle exhaust. Your truck’s HVAC system takes air from the outside environment, including emissions from nearby vehicles to recirculate as “fresh air” in your cab. As a result, your cab’s pollutant level may be 10 times higher than outside, depending on traffic density, flow and speed, the age of your truck, the type of vehicles ahead of you, and weather conditions.

Studies have found that half of the pollutants inside your vehicle may come from the gasoline and diesel exhaust of vehicles immediately ahead of you. Traffic exhaust pollution, consisting of volatile organic compounds like benzene, toluene, formaldehyde, and carbon monoxide, can trigger headaches, drowsiness, dizziness, and nausea.

Another component of traffic pollution – particulate matter (coarse and fine particles) – is particularly harmful to people with heart disease or respiratory issues. According to studies, fine particulate matter from heavy traffic can cause heart attacks and strokes for susceptible people, often within hours of exposure. Even for healthy people, particulate may affect their heart rate/rhythm, clotting, and other cardiovascular functions. Particulates also impact respiration, causing lung congestion, sinus and throat irritation, chest discomfort, and aggravating asthma.

Your exposure to pollution noticeably increases when driving in urban areas with traffic lights because the deceleration, idling and acceleration associated with red lights create concentrated points of harmful particulate matter – 29% higher than the open road. Even though passing through intersections only accounts for 2% of driving time, intersections are responsible for 25% of inhaled pollutants and driving in heavy traffic may reduce your cab’s air quality to 40% lower than in light traffic.

Your own breathing also lowers air quality. Inhaling oxygen and exhaling carbon dioxide in a closed environment depletes your oxygen supply, particularly if your HVAC system is operating in the “closed/recycle” mode to avoid outdoor-polluted air. Low oxygen levels impair your judgment and muscle coordination, and increase your heart rate.

Even the common materials contained in your cab impact air quality. Vinyl, plastic, leather, carpeting, fabrics, foam cushions, and adhesives, may all leak VOCs, especially for new vehicles in hot weather, as high heat breaks down these compounds. Chemical deodorizers and cleaning products can also emit toxic fumes.

Low air quality in your cab can have serious consequences – driver fatigue, with drowsiness, low alertness, low concentration, slowed reactions, and poor hand-eye coordination, is a primary cause of road fatalities.

Be safe and avoid these issues. Maintain the air quality in your cab while driving by doing the following: retain a distance between your vehicle and the one ahead to allow its exhaust to dissipate. In congested traffic, tunnels, and at red lights, close your windows and set your ventilation to recirculate and allow your air-conditioner to filter out most particulate matter. Select less-congested routes. In light traffic, keep your windows partially open.

In a new vehicle, drive with open windows as much as possible for a few months when the VOCs are highest. Maintain your vehicle mechanically. Keep the cab clean, since pollutants attach to dust particles, which are easily inhaled. Clean using micro-fiber cloths, not chemical cleaners. Avoid chemical air fresheners or deodorizers – use baking soda or natural products to absorb odors instead.

Take a breath of fresh air and regularly schedule time away from your rig.


Karen Bowen is a professional health and nutrition consultant, and she can be reached at

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