A chemical hazard is a (non-biological) substance that has the potential to cause harm to life or health. Chemicals are widely used in the home and in many other places. Exposure to chemicals can cause acute or long-term detrimental health effects. There are many types of hazardous chemicals, including neurotoxins, immune agents, dermatologic agents, carcinogens, reproductive toxins, systemic toxins, asthmagens, pneumoconiotic agents, and sensitizers. In the workplace, exposure to chemical hazards is a type of occupational hazard. The use of protective personal equipment (PPE) may substantially reduce the risk of damage from contact with hazardous materials. Long-term exposure to chemical hazards such as silica dust, engine exhausts, tobacco smoke, and lead (among others) have been shown to increase risk of heart disease, stroke, and high blood pressure. Types of chemical hazard Routes of exposure The most common exposure route to chemicals in the work environment is through inhalation. Gas, vapour, mist, dust, fumes, and smoke can all be inhaled. Those with occupations involving physical work may inhale higher levels of chemicals if working in an area with contaminated air. This is because workers who do physical work will exchange over 10,000 litres of air over an 8-hour day, while workers who do not do physical work will exchange only 2,800 litres. If the air is contaminated in the workplace, more air exchange will lead to the inhalation of higher amounts of chemicals. Chemicals may be ingested when food or drink is contaminated by unwashed hands or from clothing or poor handling practices. Chemical exposure to the skin is a common workplace injury and may also occur in domestic situations with chemicals such as bleach or drain-cleaners. The exposure of chemicals to the skin most often results in local irritation to the exposed area. In some exposures, the chemical will be absorbed through the skin and will result in poisoning. The eyes have a strong sensitivity to chemicals, and are consequently an area of high concern for chemical exposure. Chemical exposure to the eyes results in irritation and may result in burns and vision loss. Injection is an uncommon method of chemical exposure in the workplace. Chemicals can be injected into the skin when a worker is punctured by a sharp object, such as a needle. Chemical exposure through injection may result in the chemical entering directly into the bloodstream. Symbols of chemical hazards Hazard pictographs are a type of labeling