Pollutant Populations at Risk Effects

Ozone Healthy adults and children Decreased lung function

Increased airway reactivity

Lung inflammation

Athletes, outdoor workers Decreased exercise capacity

Asthmatics Increased hospitalizations

Nitrogen dioxide Healthy adults Increased airway reactivity

Asthmatics Decreased lung function

Children Increased respiratory infections

Sulfur dioxide Healthy adults Increased respiratory symptoms

Patients with chronic lung disease Increased mortality

Increased hospitalization

Asthmatics Decreased lung function

Acid aerosols Healthy adults Altered mucociliary clearance

Children Increased respiratory infections

Asthmatics Decreased lung function

Increased hospitalizations

Particulates Children Increased respiratory infections

Decreased lung function

Patients with chronic lung or heart disease Excess mortality

Asthmatics Increased attacks

Data from Bascom R, et al: Health effects of outdoor air pollution, Am J Respir Crit Care Med 153:3, 477, 1996.

cause increased epithelial permeability and reactivity of the airways, and decrease ciliary clearance. The highest inhaled dose is delivered at the bronchoalveolar junction; however, ozone

also causes inflammation of the upper respiratory tract.

Nitrogen Dioxide.

Oxides of nitrogen include NO and NO2 . These have lower reactivity than ozone. Nitrogen dioxide dissolves in water in the airways to form nitric and nitrous acids, which damage the

airway epithelial lining. Children and patients with asthma have increased susceptibility to nitrogen dioxide; there is a wide variation in individual responses to this pollutant.

Sulfur Dioxide.

This pollutant is highly soluble in water; it is absorbed in the upper and lower airways, where it releases H+ , HSO3 - (bisulfite), and SO3 - (sulfite), which cause local irritation.

Acid Aerosols.

Primary combustion products of fossil fuels are emitted by tall smoke stacks at high altitudes and are transported by air. In the atmosphere, sulfur and nitrogen dioxide are oxidized to

sulfuric acid and nitric acid, respectively, which are dissolved in water droplets or adsorbed to particulates. These acid aerosols are irritants to the airway epithelium and alter mucociliary

clearance. Asthmatics have decreased lung function and increased hospitalizations when exposed to acid aerosols, although there is a wide variation in airway responses.

Particulates.

As discussed in Chapter 15 , the deposition and clearance of particulates inhaled into the lungs depend on their size. Ambient particulates are highly heterogeneous in size and in chemical

composition. It is uncertain which characteristics of ambient particulates contribute to their adverse health effects. Recent epidemiologic and toxicologic studies suggest that ultrafine

particles (less than 0.1 μm in aerodynamic diameter) are more hazardous. They contribute to increased morbidity and mortality, especially among infants, the elderly, and people with

chronic cardiopulmonary disease. The mechanisms responsible for these adverse health effects are suspected to involve: (1) systemic cytokine release

associated with pulmonary inflammation; (2) increased blood viscosity; and (3) autonomic changes associated with variable heart rates and arrhythmias.[35]

Date: 2016-04-22; view: 700