Health Effects of Air Pollutants

Health Effects of Respirable and Fine Suspended Particles (PM10 and PM2.5)

PM with particle sizes less than 10 microns, which are known as respirable suspended particulates or PM10, can get deep into the lungs and cause a broad range of health effects, in particular, respiratory and cardiovascular illnesses, including – 

  •     Increasing respiratory symptoms, such as irritation of the air-ways, coughing, or difficulty in breathing;
  •     Decreasing lung function;
  •     Aggravation of asthma;
  •     Development of chronic bronchitis;
  •     Adverse effects on the cardiovascular system;
  •     Premature death in people with heart or lung disease.

People with heart or lung disease, children and the elderly are most likely to be affected by particulate pollution.

Recent medical researches show that the risk for various health impacts increases with exposure and there is little evidence to suggest a threshold below which no adverse health effects would be anticipated. It has also been shown that the health risks would be higher for those particles with particle sizes of 2.5 microns or less, which are commonly referred to as fine suspended particles or PM2.5.

Health Effects of Sulphur Dioxide

Exposure to elevated level of sulphur dioxide can cause impairment of respiratory function, aggravation of existing respiratory disease (especially bronchitis) and cardiovascular disease. In sensitive individuals, the lung function changes may be accompanied by perceptible symptoms such as wheezing, shortness of breath, and coughing. Sulphur dioxide may also lead to increased mortality, especially if elevated levels of suspended particles are also present. Major subgroups of the population that are most sensitive to sulphur dioxide include asthmatics and individuals with cardiovascular disease or chronic lung disease (such as bronchitis or emphysema) as well as children and the elderly.

Health Effects of Nitrogen Dioxide (NO2)

Nitrogen dioxide (NO2) can irritate the lungs and lower resistance to respiratory infection such as influenza. Individuals with respiratory problems, such as asthma, are more susceptible to the effects. In young children, nitrogen dioxide may also impair lung development. Studies suggest that chronic exposure to nitrogen dioxide may lead to structural changes in the lungs, however, specific levels and exposure duration likely to cause such effects have not yet been determined.

Health Effects of Carbon Monoxide

Inhaled CO enters the blood stream and binds preferentially to haemoglobin (the substance that carries oxygen to the cells), thereby replacing oxygen. It results in reducing the amount of oxygen which is delivered to body organs and tissues. The percentage of haemoglobin inactivated by CO depends on the amount of air breathed in, the concentration of CO in air and the duration of exposure. In a healthy person, elevated CO concentration exposure is associated with visual impairment, reduced work capacity, reduced mental function and poor learning ability. Persons suffering from heart and circulatory problems, fetuses, young infants, pregnant women and elderly people are likely to be more susceptible to the effects of CO .

Health Effects of Photochemical Oxidants

Ozone toxicity occurs in a continuum in which higher concentrations, longer exposure durations and greater activity levels during exposure cause greater effects. Ozone has the greatest impact on the respiratory system, where it irritates the mucous membranes of the nose, throat and airways. Symptoms associated with exposure include cough, chest pain, and throat and eye irritation. Ozone can also increase susceptibility to respiratory infection. Acute adverse effects may impair normal functioning of the lungs and induce respiratory inflammation. Healthy individuals who exercise heavily for brief periods (1 to 2 hours) may experience respiratory symptoms . They may also experience these symptoms at a lower concentration for longer exposure (6 to 8 hours) during moderate exercise. Individuals with sensitive respiratory systems (such as with asthma or respiratory disease) are more susceptible to the effects of ozone.

Other photochemical oxidants, such as peroxyacyl nitrates and aldehydes, are associated with eye irritation.

Health Effects of Lead

Lead is a toxic heavy metal which can be found in total or respirable suspended particulates. Lead particles from vehicular exhausts which are of a size smaller than 10 micrometres can affect both adults and children, but small children (and foetuses) are at greatest risk because of their smaller size, breathing patterns and the metabolism of lead in their bodies. The effects of lead exposure include damage to the nervous system, red blood cells, kidneys and potential increases in high blood pressure. Other health effects may result in decreased co-ordination and mental abilities. The effects of lead exposure can be treated and reversed, providing treatment is timely and lasts the entire course of therapy. If no treatment is given, permanent brain damage can result.

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