Air pollutionJapan

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Traffic rules

Japan

77. Air pollution

Air pollution is the presence of gases, particles or other substances in the air at concentrations that can harm human health, the environment or ecosystems. Road traffic contributes to air pollution through exhaust emissions and through non-exhaust sources such as brake wear, tyre wear and road dust.

Important traffic-related pollutants include nitrogen oxides, particulate matter, carbon monoxide and volatile organic compounds. Some pollutants are emitted directly by vehicles, while others can form in the atmosphere through chemical reactions. Vehicle-emission standards, cleaner technologies and traffic-management measures are used to reduce these emissions.

Black smoke emitted from a vehicle exhaust on a road in Kamonyi District. (Rwanda)
Wikimedia.org • Emmanuelkwizera • CC BY-SA

What is air pollution?

Air pollution is contamination of the air by gases, particles or other substances that can adversely affect human health, the environment or ecosystems.

How does road traffic cause air pollution?

Vehicles produce pollutants through fuel combustion, exhaust systems, brake wear, tyre wear and road-surface interaction. Moving traffic can also resuspend dust already present on the road.

Which air pollutants are associated with road traffic?

Important traffic-related pollutants include nitrogen oxides, particulate matter, carbon monoxide and volatile organic compounds. Their relative importance depends on the vehicle, fuel and driving conditions.

What is nitrogen dioxide?

Nitrogen dioxide (NO2) is an air pollutant associated particularly with combustion processes and road traffic. High concentrations are commonly found near busy roads and densely trafficked urban areas.

What is particulate matter?

Particulate matter consists of tiny solid particles or liquid droplets suspended in the air. Road traffic can produce particles from exhaust, brakes, tyres and road surfaces.

Is CO2 the same as ordinary air pollution?

No. Carbon dioxide is primarily regulated as a greenhouse gas because of its contribution to climate change. Local air-quality pollution generally focuses on substances such as nitrogen dioxide, particulate matter, ozone and other pollutants that directly affect air quality and health.

Do electric vehicles cause air pollution?

Fully electric vehicles produce no combustion-engine exhaust emissions while driving, but they can still contribute to non-exhaust particulate emissions through tyres, brakes and road wear.

Can air pollution be worse near busy roads?

Yes. Concentrations of traffic-related pollutants can be higher close to heavily trafficked roads because many emissions occur close to ground level and near where people live and travel.

What is a low-emission zone?

A low-emission zone is an area where access by more polluting vehicles is restricted in order to reduce traffic-related air pollution. Access criteria may depend on factors such as fuel type, vehicle category and emission standard.

How can traffic-related air pollution be reduced?

Measures include cleaner vehicles, stricter emission standards, effective emission-control equipment, low-emission zones, public transport, cycling and walking, as well as traffic-management measures that reduce unnecessary congestion and emissions.

Particulates

Rush hour

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