Control of lead in air

The ban on the use of leaded gasoline in the 1970s produced one of the most successful episodes in the search for the control of air pollutants. As already noted, the concentration of lead in the air dropped dramatically and to very low levels within a matter of years after the ban was put into place. Currently, efforts to control lead emissions focus on improving the methods used to remove lead from air and water wastes of smelters, metal processing plants, and other such plants. The most common systems currently used are variations of traditional waste control techniques in which physical devices (such as baghouses) or chemical systems (such as precipitation reactions) are used to extract particles of lead from wastes. 

HCHs are readily absorbed through the gastrointestinal tract. Inhaling air contaminated with isomers of HCH can also lead to systemic absorption. HCHs can also be absorbed through the skin when used as a lotion, cream, or shampoo for the treatment or control of ectoparasites. In general, HCH isomers and their metabolites can be temporarily stored in body fat. Absorbed HCHs are mainly excreted via the urine. Lesser amounts are excreted in feces. In rats, the highest concentrations have been found in liver, kidneys, body fat, brain and muscles, with substantial deposition occurring in fatty tissue. 

The key to controlling sample dispersion in air-segmented flow analysis is the addition of confluent streams. After the confluence point, an increase in the length of each plug (Eq. 3.12) leads to an increase in the length of the entire sample zone. This does not result in a broader recorded peak, however, because the sample linear speed is... 

The effectiveness of control measures should be assessed by all of the following methodologies (i) static atmospheric monitoring (ii) personal lead-in-air monitoring... 

Increased use of leaded gasoline in Canada may generate pressures to control automotive exhaust lead emissions, although there is no established health-based lead-in-air standard to serve as the basis for such control. If reduction of automotive lead emissions into the atmosphere should be required, controls should be placed on the amount of lead emitted from the tailpipe, similar to the manner by which gaseous emissions are controlled. Such action is more energy efficient than reducing the amount of lead used in gasoline. One effective way to control tailpipe lead emissions is the use of automotive exhaust lead trap that replaces the standard muffler (2). 

In most countries, the primary control employed is a limit on the amount of lead in the air breathed by the worker. This in turn influences the amount of lead to which the worker may be exposed elsewhere in the workplace (on surfaces, etc.) and considerable emphasis is usually placed also on general cleanliness and good working practice to limit exposure from such sources. The ultimate purpose in all cases is, of course, to protect the health of the individual worker and so health monitoring of the workforce is also conducted. This can take the form of... 

---