Vehicular Exhaust and Air Pollution

Introduction

Individual tailpipe emissions

Transport and fate in the environment

Measuring exposures

Prevention and control of exposure

Exposure Pathway

Risk assessment

Adverse effects


Harmful Effects

Dose Response

Absorption, Metabolism and Molecular Mechanisms of Action

Organ Sites of Toxicity

Biomarkers

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Harmful Effects

From previous links, it is understood that vehicular exhaust contains various constituents. The information for all of them is an overwhelming task. To be more specific to the needs of anyone browsing this site, we’ve decided to narrow the aspects of the health effects to just ozone (O3) and Particulate Matter (PM), two of the main factors of photochemical smog, which plague every metropolitan area.

Ozone

The main area on which ozone effect an animal or human is the respiratory tract. Based on numerous studies performed, ozone effects:

1. A host’s defensive mechanisms

The mucous lining of the nasal cavity had structural changes and cilia were lost or damaged at low concentrations. Mucous chemistry changed and mucociliary particle clearance was slowed from acute exposures. As a secondary effect, the inability to protect the respiratory tract leads to a higher risk of bacterial and viral infections.

2. Inflammation and permeability

Ozone causes inflammation of the lungs and allows for substances to transfer between the blood and fluid of the lungs that normally wouldn’t occur.

Others studies have been performed to observe if ozone has a genotoxicity or carcinogencity. All of the experiments were performed with a higher concentration of ozone than what is present in ambient area or which is produced from vehicular exhausts. Based on animal studies, it was determined that ozone is a very weak mutagen, however, a human study performed returned a negative result. Ozone did caused female mice in one particular study to produce tumors. But again, this result was at a high concentration over a long period of time. Currently, more research is needed to determine if ozone can cause cancer and at what concentration.

There is no systemic effects directly linked to ozone, however, some reports show that by-products of ozone reactions can cause effects to the central nervous system circulatory system and the liver.

Particulate Matter

Most of the time, particulate matter is broken down into two categories, PM10 and PM2.5. However, for this section of the site, the two different categories are going to be neglected and the health effects will be concerned with particulate matter as a whole. Acute exposure to particulate matter causes common respiratory effects, such as coughing, wheezing and shortness of breath. But these effects could not be separated based on particulate matter alone. The effect of these short term effects are only relatable to all pollutants in general, not just particulate matter. A small number of long-term studies were conducted. The findings did not support a relationship between long-term particulate matter exposures and health effects.