Ventilatory support with low tidal volume, high-frequency oscillatory ventilation (HFOV) usually uses a bias flow system to provide fresh gas. Although the bias flow rates (Vbf) used previously have varied widely among experimental configurations, the precise role of the bias flow in HFOV-mediated gas transport has not been defined. We assessed the effect of bias flow rate on gas transport during HFOV by measuring CO2 removal rate (MCO2) in anesthetized, paralyzed dogs, using a wide range of bias flow rates (0.7-28.9 L X min-1). When a fixed tidal volume of 40 ml was applied at HFOV frequencies of 2-12 Hz, MCO2 was proportional to the time-averaged alveolar-bias flow CO2 concentration difference. Thus, when Vbf was reduced below a value which resulted in a substantial increase in bias flow CO2 concentration, MCO2 was reduced. These findings are consistent with a simple framework in which the relative magnitudes of the resistances to gas transport of the airways and of the bias flow (1/Vbf) determine the contribution of the bias flow rate to overall gas transport during HFOV. This relationship may be employed to assess the intra-airway contribution to HFOV-mediated gas transport at any bias flow rate, and may therefore allow comparison of results from experiments utilizing various bias flow rates.

(1962). Health Aspects of Air Pollution. Archives of Environmental Health: An International Journal: Vol. 4, No. 3, pp. 221-229.

In the first edition of her Industrial Toxicology, Dr. Alice Hamilton had the following to say: &dquo; ... A great deal of money has been wasted by well-meaning employers who sought to protect lead furnace men or oxide roasters or white lead grinders against poisoning, by providing baths and lunchrooms and clean overalls and mouth washes and such, instead of preventing the escape of lead into the air the men were obliged to breathe, and unfortunately this has sometimes been done under a physician’s advice. It must never be forgotten that the great majority of industrial poisons enter the body with the inspired air and that while a workman eats only three times a day he breathes sixteen times a minute during the eight or ten hours of his working day.&dquo; These are maxims and guides which we will always apply in practice of industrial hygiene and in air pollution control.

Industrial Disabilities and Compensation Insurance Of the disabilities falling within the jurisdiction of our various State Compensation Boards in the United States roughly 97% are accidents; about 3% are chronic diseases like benzol poisoning or silicosis. Of these 3% about two-thirds are dermatoses. In cost of time lost and of medical care the occupational diseases rank high, and actually may assume the spotlight of attention. Our compensation awards are covered by insurance placed by the employers through insurance companies or through State insurance. In Ohio, for example, compensation insurance is a State monopoly, while in New York an employer can insure either with a private company or with the State. If the employer posts a bond for an amount approved by the State he can be selfinsured. The premiums paid are revised periodically according to the experience or record. When the experience is very bad the premium charges may be so high that the employing company cannot afford to insure, or the insurance company can simply refuse to accept the risk. In such an event the Insurance Commissioner of the State can pro-rate the policy among companies doing business in the State, and the companies then become the reluctant recipients of the business. The result of this method of compensation insurance is that the companies writing the policies have developed first-class inspection schemes, with excellent staffs of industrially minded physicians, engineers, industrial hygienists, and chemists, and it is to the interest of insured and insurer to cut lost time to the minimum. In the policies freedom of entry and inspection is given to the insurance companies. Their men visit the insured companies and give them valuable consulting service. The insurance companies' inspection scheme reminds one very much of your British Government inspectorate. Yours is more than a century old while ours is very young. But your Governmental inspectors, operating from your Ministry of Labour in London-and distribuited all over industrial Britain, have no opposite number in our Federal Government set-up. The industrial hygiene laboratories of the Public Health Service are available to industry for consultation and research. Their surveys of various industries have often set the

Four thousand deaths were attributed to this London pollution incident lasting 4 to 5 days. Maximum smoke concentrations in area was 4.46 mg/m/sup 3/ and 3 to 10 times normal at all stations. Maximum SO/sub 2/ concentration was 1.34 ppM and 3 to 12 times normal elsewhere. Ratio of the two avg 2.4 (range 1 to 4) and was remarkably constant. Peak death rate paralleled SO/sub 2/ and smoke levels but remained abnormally high for days after episode. Death rate was also higher than average before actual episode. Eighteen % of 200 million tons coal consumed is used in London for home heating (no pollution control equipment), and these domestic fires contribute 40% of smoke as a whole and 60% in winter. Stacks above fog banks would have little effect. SO/sub 2/ from combustion and CO are mainly from autos.