1. What is byssinosis?
2. Did OSHA demonstrate that the Cotton Dust Standard was reasonably necessary or appropriate to protect employees against a significant risk of health impairment as required by the Industrial Union Department v. American Petroleum Institute decision?
3. Does the Occupational Safety and Health Act require the Secretary of Labor, in promulgating a standard pursuant to Section 6(b)(5), to determine that the costs of the standard bear a reasonable relationship to its benefits?
4. Was the Secretary of Labor’s determination on economic feasibility supported by substantial evidence?
5. Did the Secretary (OSHA) make the necessary determinations that the wage guarantee requirement was related to the achievement of a safe and healthful work environment?

[The Secretary of Labor, acting through the Occupational Safety&Health Administration, promulgated the so-called Cotton Dust Standard limiting occupational exposure to cotton dust, exposure to which induces byssinosis, a serious and potentially disabling respiratory disease known as "brown lung" disease. Petitioners, representing the cotton industry, challenged the validity of the standard in the court of appeals, contending that the Act requiresOSHA to demonstrate that the standard reflects a reasonable relationship between the costs and benefits associated with the standard, that OSHA's determination of the standard's "economic feasibility" was not supported by substantial evidence, and that the wage guarantee requirement contained in the standard was beyond OSHA's authority. The court of appeals upheld the standard in all major respects.]
BRENNAN, J.…
I.
Byssinosis, known in its more severe manifestations as "brown lung" disease, is a serious and potentially disabling respiratory disease primarily caused by the inhalation of cotton dust.* Byssinosis is a "continuum … disease," that has been categorized into four grades. In its least serious form byssinosis produces both subjective symptoms, such as chest tightness, shortness of breath, coughing, and wheezing, and objective indications of loss of pulmonary functions. In its most serious form, byssinosis is a chronic and irreversible obstructive pulmonary disease, clinically similar to chronic bronchitis or emphysema, and can be severely disabling. At worst, as is true of other respiratory diseases including bronchitis, emphysema, and asthma, byssinosis can create an additional strain on cardiovascular functions and can contribute to death from heart failure. One authority has described the increasing seriousness of byssinosis as follows:
"In the first few years of exposure [to cotton dust], the symptoms occur on Monday, or other days after absence from the work environment;
later, symptoms occur on other days of the week; and eventually, symptoms are continuous, even in the absence of dust exposure." A. Bouhuys, Byssinosis in the United States, Exhibit 6-16, Joint App. 15.
While there is some uncertainty over the manner in which the disease progresses from its least serious to its disabling grades, it is likely that prolonged exposure contributes to the progression. It also appears that a worker may suddenly contract a severe grade without experiencing milder grades of the disease.
Estimates indicate that at least 35,000 employed and retired cotton mill workers, or 1 in 12 such workers, suffers from the most disabling form of byssinosis. The Senate Report accompanying the Act cited estimates that 100,000 active and retired workers suffer from some grade of the disease. One study found that over 25 percent of a sample of active cotton preparation and yarn manufacturing workers suffer at least some form of the disease at a dust exposure level common prior to adoption to the current standard. Other studies confirm these general findings on the prevalence of byssinosis.
Not until the early 1960s was byssinosis recognized in the United States as a distinct occupational hazard associated with cotton mills. In 1966, the American Conference of Governmental Industrial Hygienists (ACGIH), a private organization, recommended that exposure to total cotton dust be limited to a "threshold limit value" of 1,000 micrograms per cubic meter of air (1000 μg/m3) averaged over an 8-hour workday. The United States government first regulated exposure to cotton dust in 1968, when the Secretary of Labor, pursuant to the Walsh-Healey Act, 41 U.S.C. § 35(e), promulgated airborne contaminant threshold limit values, applicable to public contractors, that included the 1000 μg/m³ limit for total cotton dust. 34 Fed. Reg. 7953 (1969). Following passage of the Act, in 1970, the 1000 μg/m³ standard was adopted as an "established federal standard" under § 6(a) of the Act, 29 U.S.C. § 655(a).…
[In 1974] the Director of the National Institute for Occupational Safety and Health (NIOSH), pursuant to the Act, 29 U.S.C. §§ 669(a)(3), 671(d)(2), submitted to the Secretary of Labor a recommendation for a cotton dust standard with a permissible exposure limit (PEL) that "should be set at the lowest level feasible, but in no case at an environmental concentration as high as 0.2 mg lint-free cotton dust/cu.m.," or 200 μg/m³ of lint-free respirable dust….

The Cotton Dust Standard promulgated by OSHA establishes mandatory PELs over an 8-hour period of 200 μg/m3 for yarn manufacturing, 750 μg/m³ for slashing and weaving operations, and 500 μg/m3 for all other processes in the cotton industry.These levels represent a relaxation of the proposed PEL of 200 μg/m³ for all segments of the cotton industry.
OSHA chose an implementation strategy for the standard that depended primarily on a mix of engineering controls, such as installation of ventilation systems, and work practice controls, such as special floor sweeping procedures. Full compliance with the PELs is required within four years, except to the extent that employers can establish that the engineering and work practice controls are feasible. During this compliance period, and at certain other times, the Standard requires employers to provide respirators to employees. Other requirements include monitoring of cotton dust exposure, medical surveillance of all employees, annual medical examinations, employee education and training programs, and the posting of warning signs. A specific provision also under challenge in the instant case requires employers to transfer employees unable to wear respirators to another position, if available, having a dust level at or below the Standard's PELs, with "no loss of earnings or other employment rights or benefits as a result of the transfer."