Vehicle Idling & Carbon Monoxide

Some 480,000 school buses travel four billion miles each year. School buses are the safest way for children to get to school. Twenty-five million American children ride school buses daily and on average, these students spend an hour and a half each day in a school bus. In comparison, it would take an average of 17 million cars to transport the same number of students.


Air pollution from older diesel vehicles and school buses has health implications for everyone, especially children. Children are more susceptible to air pollution because their respiratory systems are still developing and they have a faster breathing rate. In addition to producing a number of hazardous pollutants, diesel exhaust contains significant levels of particulate matter that can deposit into the lungs and can cause lung damage and aggravate respiratory conditions such as asthma.

Vehicle Idling:

Idling vehicles contribute to air pollution and emit air toxins, which are pollutants known or suspected to cause cancer or other serious health effects. This is yet another important issue that affects children’s health at school when parents idle their vehicles during student drop-off and pick-up. Exhaust produced by idling vehicles can be pulled into a school through the air intakes of the building’s heating, ventilating and air conditioning
(HVAC) system where it can accumulate and cause serious health issues for staff and students.
In addition to other environmental benefits, reducing vehicle idling has a number of financial benefits: reduced fuel costs, energy costs and unnecessary engine wear.

Steps to Reduce Vehicle Exhaust at Schools:

Encourage policies to eliminate unnecessary school bus idling.

Upgrade or “retrofit” buses and replace older vehicles with newer, more efficient models.

Establish anti-idling zones for all vehicles at the school (school buses, delivery trucks and parents).

Locate passenger pickup and drop off areas away from a school’s air intake supply and classroom windows.

Carbon monoxide (CO)

Carbon monoxide (CO) is a colorless, odorless gas. It results from incomplete oxidation of carbon in combustion processes. Common sources of CO in schools are improperly vented furnaces, malfunctioning gas ranges, and exhaust fumes that have been drawn back into the building. Worn or poorly maintained combustion devices (e.g., boilers, furnaces), or a flue that is improperly sized, blocked, disconnected, or leaking, can be significant sources. Auto, truck, or bus exhaust from attached garages, nearby roads, or idling vehicles in parking areas can also be sources. Exposure to concentrated levels of CO may result in a variety of flu-like symptoms such as dizziness, fatigue, headaches, disorientation and nausea. High levels of exposure can result in loss of consciousness and death. Combustion equipment must be maintained to assure that there are no blockages, and air and fuel mixtures must be properly adjusted to ensure more complete combustion. Vehicular use should be carefully managed adjacent to buildings and in vocational programs. Additional ventilation can be used as a temporary measure when high levels of CO are expected for short periods of time.

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