Category Archives: Environmental medicine

Sick building syndrome

The World Health Organization has defined the sick building syndrome as an excess of work-related irritation of the skin and mucous membranes (usually eyes, nose and throat) and other symptoms including headache, fatigue and difficulty in concentrating reported by workers in modern office buildings. In 25% of cases a specific cause has been found, such as contamination of humidification systems, but in the r

Motion sickness

This common problem, particularly in children, is caused by repetitive stimulation of the labyrinth of the ear. It occurs frequently at sea and in cars, but may occur on horseback or on less usual forms of transport such as camels or elephants. Nausea, sweating, dizziness, vertigo and profuse vomiting occur, accompanied by an irresistible desire to stop moving. Prophylactic antihistamines or vestibular sedati

Ultraviolet light

Ultraviolet (UV) light consists of UVB (wavelength 290-320 nm) and UV A (320-400 nm). Wavelengths 100- 290 nm are stopped by the ozone layer. • UVB causes sunburn. • UV A and UVB cause skin ageing and skin cancer. Sunscreens absorb UV energy but many preparations only absorb UVB. The sun protection factor (SPF) is a guide  on the sunscreen performance, but there is no worldwide standard and often the prot

Drowning and near drowning

Drowning is a common cause of accidental death, accounting for over 100000 deaths annually worldwide. Approximately 40% of drownings occur in children under 5 years of age. Exhaustion, alcohol, drugs and hypothermia all contribute to the overall problem. In addition, drowning can also occur following an epilepticr attack or after a myocardial infarct whilst in the water. Dry’ drowning Between 10 and 15%


The intensity of sound is expressed in terms of the square of the sound pressure. The bel is a ratio and is equivalent to a lO-fold increase in sound intensity; a decibel (dB) is one-tenth of a bel. Sound is made up of a number of frequencies ranging from 30 hertz (Hz) to 20 kHz, with most being between 1 and 4 kHz. When measuring sound, these different frequencies must be taken into account. In practice a s


Smoke consists of particles of carbon in hot air and gases. These particles are mainly coated with organic acids and aldehydes. Use was widespread of synthetic materials (e.g. polyvinyl chloride) that release other substances, such as carbon monoxide and hydrochloric acid, on combustion. Respiratory symptoms may be immediate or delayed. Patients are dyspnoeic and tachypnoeic. Laryngeal stridor may require in

Electric shock

Electric shock may produce clinical effects in three ways: 1 Pain and psychological sequelae. The common ‘electric shock’ is usually a painful, but harmless, stimulus that is an unpleasant and frightening experience. It produces no lasting neurological damage or cutaneous evidence of damage. 2 Disruption of specific biological processes. Ventricular fibrillation, muscular contraction and spinal cor

Ionizing radiation

Ionizing radiation is either penetrating (X-rays, ‘}’-rays or neutrons) or non-penetrating (a or f3 particles). Penetrating radiation affects the whole body, while nonpenetrating radiation only affects the skin. All radiation effects, however, depend on the type of radiation, the distribution of dose and the dose rate. Absorption of doses greater than 100 rads of y-radiation, e.g. following surviv


The increases in ambient pressure to which a diver is exposed at various depths are summarized. Various methods are used to supply air to the diver. With the simplest, e.g. a snorkel, the limiting factor, which occurs below 0.5 m, is the respiratory effort required to suck air into the lungs. At greater depths this ‘forced negative-pressure ventilation’ ultimately results in pulmonary capillary da

High altitudes

The partial pressure of ambient (and hence alveolar and arterial) oxygen falls in a near-linear relationship to altitude. Below 3000 m there are few important clinical effects. Commercial aircraft are pressurized to 2750 m and the resulting hypoxia causes breathlessness only in those with severe cardiorespiratory disease. The incidence of thromboembolism is, however, slightly greater than at sea level in sede