If one considers the primary sector of economic activity to consist of those jobs and industries dealing with the extraction of raw materials (e.g. mining, fishing, agriculture), and the secondary sector centering on manufacturing of goods, services industries are often considered to represent the ‘tertiary’ sector. Typically, in the most economically developed countries, over half of the working population labors in service-related businesses. In the United States, service-based workers outnumber workers in manufacturing by about 8 to 1.

Healthcare workers (HCWs) comprise approximately 8% of the US workforce and roughly half of the top 30 fastest growing occupations. Hospitals and other inpatient healthcare settings house potential exposures that cover the full spectrum of workplace hazards, including biological, physical, chemical, radiation agents and psychosocial risk factors. In the 1990s, particular attention centered on respiratory issues in HCWs, partly due to increased concerns over occupational latex allergy that emerged following a significant increase in the use of latex-containing personal protective equipment, such as powdered gloves, to counter the risks of nosocomial and occupationally acquired infection. Putative respiratory hazards in healthcare environments go beyond latex, and include disinfectants/sterilants (e.g. glutaraldehyde, formaldehyde), pharmaceuticals (e.g. psyllium, various antibiotics, platinum-containing antineoplastic agents), sensitizing metals (e.g. dental alloys), methacrylates, aerosolized medications (e.g. pentamidine, ribavirin), general cleaning agents and infectious agents. Respiratory health effects consist primarily of upper and lower airway irritative and allergic syndromes, and occupational infections.

Airways disease

Different countries have reported work-related asthma among physicians, respiratory therapists, workers in endoscopy units and radiology departments, nurses and general HCWs. The agents most often associated with these reported asthma cases include latex, cleaning products and poor indoor air quality.

Physician-diagnosed asthma developing after entry into the profession appears to especially affect nurses and respiratory therapists, and is significantly associated with medical instrument cleaning, exposure to general cleaning products, use of powdered latex gloves and the administration of aerosolized medications.

Sensitization to latex products can vary in type. At least 13 botanical proteins present in the rubber tree and in the finished products have been characterized as potential sources of type I allergy. Type I hypersensitivity results in an immediate reaction in the form of localized urticaria and erythema at the site of the exposure; this can be evidenced with careful skin prick tests. Immediate systemic reactions can also occur, including a diffuse rash, conjunctivitis, rhinitis, bronchospasm and, rarely, hypotension, anaphylaxis and death. Latex gloves, particularly when powdered, have been linked to these type I reactions. Bound by cornstarch powder during the manufacturing process, the latex proteins can be aerosolized through the handling, donning and removal of powdered latex gloves.

Type IV hypersensitivity reactions have also been observed in association with latex glove use, although whether this is due to the latex proteins themselves is debatable. In sensitized individuals, type IV delayed hypersensitivity manifests 6-72 hours postexposure, causing contact allergic dermatitis. However, in most cases, these delayed reactions are attributable to additives used in the manufacturing process of rubber gloves rather than to the latex proteins themselves. Allergy can be confirmed through patch skin testing for these additives.

There is evidence that latex control policies implemented in hospitals over the past several years are having a beneficial impact. In 1997, in response to increasing reports of latex allergic reactions, hospitals in the USA were advised to reduce unnecessary use of powdered latex gloves. Although overall sales in the USA continued to increase, the total protein and powder content in latex gloves decreased markedly. A subsequent decrease in numbers of reported cases of latex allergy has been observed, underscoring the effectiveness of substitution of powdered latex gloves by low-latex alternatives and other workplace control measures.

Glutaraldehyde is commonly used in endoscopy units for cold sterilization, particularly for disinfecting heat-sensitive equipment, including fiberoptic endoscopes, dialysis instruments and surgical instruments; it is also used as a tissue fixative in pathology laboratories or for developing radiographs, and can act as both a respiratory irritant and sensitizer. Instrument cleaning products linked to sensitization and occupational asthma may also include enzyme-containing products, such as subtilisins (detergent protease enzymes). Chronic bronchitis, nasal symptoms, and the onset of ‘multiple chemical sensitivity’ have been reported in workers using glutaraldehyde, as have higher prevalences of headache, fatigue and irritation of skin, eyes and throat than among those without this exposure. Moreover, glutaraldehyde has also been linked to the occurrence of occupational asthma, especially among respiratory therapists and nurses who routinely sterilize endoscopes with this compound. Many health and safety authorities have recommended implementation of controls, including enclosure and automation of cold sterilization procedures, and substitution of glutaraldehyde with less toxic alternatives. In many hospitals, glutaraldehyde is being replaced with orthophthalaldehyde, also a high-level disinfectant and presumably less of a sensitizer.

Ethylene oxide gas has been widely used to sterilize heat-labile medical equipment in central supply and sterilizing units. Overexposures typically occur with use of faulty equipment, poor work practices or when gas tanks are changed out. Acute inhalation of high concentrations of ethylene oxide can produce both upper and lower respiratory tract irritation, including bronchospasm and, in rare cases, reactive airways dysfunction syndrome (RADS) or sensitization. In addition, this gas has neurotoxic properties, leading to central nervous system effects, including headache, nausea and loss of coordination. Concerns regarding the effects of chronic exposure to ethylene oxide have mostly centered on neurotoxicity (peripheral neuropathy) and carcinogenicity, as it is considered a Class I (i.e. definite) human carcinogen by the International Agency for Research on Cancer. Modern hospitals have implemented control measures for ethylene oxide use, including area detection monitors, enclosure systems, use of self-contained breathing apparatuses to manage leaks and substitution of ethylene oxide with alternate sterilization methods, such as hydrogen peroxide gas plasma.

Both occupational and work-aggravated asthma among radiographers also occurs. The process of ‘wet’ radiography involves the use of X-rays to create an image on a film surface by the reduction of silver halide crystals to elemental silver. During film development, reducing agents such as hydroquinone are used to enlarge and stabilize the image followed by fixing agents that are used to dissolve the unused halides. Automated film processing machines use higher temperatures, typically in the range of 28-35° C, to achieve shorter developing times. These machines use hardening agents such as glutaraldehyde within the developer solution and hot air to dry and fix the film. Film developing in confined, less well ventilated spaces, such as in some mobile radiography units, may enhance exposure opportunities. Additionally, radiographers are potentially exposed to glycols, acetic acid, sodium sulfite, sulfur dioxide, ammonium chloride, silver compounds and other chemicals that may cause or exacerbate asthma. With the increasing shift from traditional film developing to digital radiography, however, it is likely that cases of airway syndromes in radiographers will decrease in coming years.

Cases of RADS and persistent symptoms of bronchial hyper-responsiveness have been described in HCWs following exposure to acute chemical spills, such as glacial acetic acid. In the UK, numbers of reported inhalation accidents among health service staff have been found to be high, mostly due to anesthetic gases and cleaning agents. It is less well established whether chronic low-level exposure to irritants can lead to asthma, although certainly airborne irritants can trigger asthma exacerbations. In summary, workers in healthcare settings are at an increased risk of both upper airway syndromes and asthma, both immunologically and nonimmunologically induced. Despite this, important gaps in knowledge remain with respect to better risk characterization of at-risk HCW subgroups, identification and assessment of specific agents within the broad exposure categories mentioned herein, monitoring of trends in asthma rates over time, estimation of the impact of asthma on work patterns and productivity among healthcare workers, and effectiveness of preventive measures.

Respiratory infections

Transmission of tuberculosis, one of the oldest occupational diseases linked to work in healthcare settings, remains a threat to HCWs, especially in developing nations. Risk of occupationally acquired tuberculosis is greater in certain healthcare settings, including those with a high proportion of patients from correctional facilities, indigent populations and/or HIV infection. In addition, risk preferentially affects selected HCW subgroups (e.g. pulmonary physicians, nurses and respiratory therapists) and those persons performing or involved in cough-inducing procedures (e.g. administration of nebulized medications, bronchoscopy or intubation).

In the mid-1980s and early 1990s, cases of multidrug-resistant tuberculosis were reported among HCWs in the USA, mostly in nursing home settings and correctional facilities, and primarily occurring in HIV-infected HCWs. In response to the emerging threat, in 1994 the Centers for Disease Control and Prevention issued guidelines for preventing the transmission of tuberculosis in healthcare settings. The focus of the 1994 guidelines was on assessment of risk in a given facility, followed by implementation of environmental, administrative and personal protection controls commensurate with that risk. These guidelines were widely adopted in the country, with a resulting decrease in outbreaks of tuberculosis in healthcare settings, lowered transmission rates between patients and workers, and a decline in multidrug-resistant tuberculosis. By 2004, the national tuberculosis rate was the lowest on record, reflected by fewer reports of occupationally acquired active tuberculosis and decreasing rates of tuberculin skin test conversions on periodic surveillance exams among HCWs. Revised guidelines were published in 2005, emphasizing measures to maintain the success achieved and to eliminate remaining threats to HCWs, mostly from patients or persons with as yet undiagnosed active infection. Notwithstanding these improved trends, multidrugresistant tuberculosis among HCWs remains a threat in developing and rapidly industrializing nations, where background rates of both tuberculosis and HIV infection may be high and access to the same control measures used in developed countries is often limited.

Dental personnel, including dentists, dental assistants, dental nurses and dental hygienists, are potentially exposed to a variety of allergens, and there is limited evidence that the incidence of occupational respiratory disease among dental professionals has increased in recent years. Among the exposures are methacrylates, used in bonding agents and resins; natural rubber latex proteins in gloves, accelerators and antidegradants in natural and synthetic rubber gloves; and glutaraldehyde in disinfectants.

Methacrylates (including methyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, ethylene glycol dimethacrylate and triethylene glycol dimethacrylate) are established type IV contact allergens. Exposure to these compounds has been linked to the development of allergic contact dermatis (pulpitis of fingertips, or dermatitis of the face caused by airborne methacrylates) as well as to respiratory hypersensitivity.

Daily use of methacrylates has been related to an increased risk of adult-onset asthma, nasal symptoms and work-related cough or phlegm. Exposure-response relationships between increasing years of exposure to methacrylates and risk of nasal symptoms, hoarseness, dyspnea and wheezing with dyspnea have been observed. It is unclear whether a history of atopy or pre-existing allergic contact dermatitis predisposes to subsequent development of respiratory hypersensitivity to these compounds.

Other potential allergens include the various metals in restorations and dental appliances, as well as miscellaneous antimicrobials and preservatives. Occupational exposures to these agents, for the most part, produce type I or type IV allergic reactions, although IgE-independent occupational asthma and protein-based contact urticaria are also possible.

Latex-induced allergic reactions are well described in dental personnel but, as is the case for other HCWs, the prevalence of type I natural rubber latex allergy is likely to be declining, partly due to increased recognition and the introduction of stricter controls in natural rubber latex product manufacturing, resulting in gloves with a lower protein content and the implementation of latex control policies in workplaces where latex end products are used.

In the veterinary professions, possible respiratory exposures include hair, dandruff, feathers, latex, mites, organic dust, disinfectants and ammonia. The incidence of occupational illness and injury claims in veterinary personnel can be up to 3 times greater than among general practitioners of medicine, and nearly a quarter of the claims are for respiratory and contact allergic reactions. Besides animal-related allergies, other respiratory illnesses reported include latex allergy, alveolitis and toxic respiratory disease.

Swine veterinarians have unique exposures in addition to those listed above. Working in swine confinement units is associated with exposure to toxic gases, endotoxin, ammonia and dust. High prevalences of work-related upper and lower respiratory symptoms occur, together with an association between abnormal pulmonary function and increased number of hours working in the barns.

In research animal laboratory workers, both allergic and irritant upper airway symptoms, skin rashes and, to a lesser extent, asthma are common. Allergic reactions are usually through type I IgE-associated hypersensitivity caused by dermal or respiratory exposure to animal allergens found primarily in dander and secretions present in urine and saliva. The prevalence of allergic symptoms to laboratory animals may be high, affecting up to or over 40% of these professionals over a lifetime; around 8% at any given time have positive skin prick tests to laboratory animal antigens, and 18% have positive nonspecific bronchial challenge tests. Dose-response relationships between allergy and weekly hours of exposure to laboratory animals and number of different animal species handled have been observed as well. Preventive measures should emphasize and favor engineering controls, including local exhaust ventilation, frequent bedding changes and use of dustless bedding, over personal protective equipment.

Cosmetology professionals, including barbers, hairdressers and manicurists, are potentially exposed to various sensitizing and irritating chemicals. Sensitizing agents include persulfate salts contained in hair bleaches, reactive dyes, epilating substances, antiseptics, formaldehyde, henna, fungi and latex. Irritants include cosmetic agents, reactive dyes, epilating substances, antiseptics, perfumes, shampoos and hair creams/ gels. Task-related risk factors for the development of respiratory disease involve performing more chemical applications, hair styling, shaving and honing of razors, and application of artificial nails. The potential for significant exposures can be enhanced by the work environment characteristics of many hairstyling and nail salons, such as small square footage and inadequate ventilation.

Professionals in the cosmetology industry are more than 3 times more likely to leave their profession due to concerns for their health, most notably hand eczema or asthma. The most common adverse respiratory effects encountered are upper and lower airway syndromes, including rhinitis with or without eye symptoms, dry or productive cough, dyspnea, wheezing, asthma and chronic bronchitis. With respect to asthma in cosmetology professionals, up to 40% can develop their asthma after entry into the profession. Among the causes of occupational asthma are persulfate salts in hair bleaches and henna, used in organic hair dyes and for temporary tattoos. Moreover, asthma exacerbations commonly occur during shaving and honing of razors, and hairstyling, including use of hair lacquers and permanent wave solutions.

There is also some evidence of adverse effects on lung function among hairdressers, and reports of parenchymal lung disease, including alveolitis, lung granulomatosis associated with exposure to polyvinylpyrrolidone in hair lacquers and idiopathic pulmonary fibrosis, a chronic diffuse interstitial lung disease of unknown cause characterized pathologically by inflammation and fibrosis of the lung parenchyma, which occurs at higher rates in this occupational group.

Nail salons (which can be part of a hair salon or stand-alone facilities) have other potentially unique exposures. Artificial nails contain varying combinations of acrylics, gel, fiberglass and porcelain, and are applied to the natural nails using glues such as ethyl cyanoacrylates. Much of the work is performed in the vicinity of the manicurist’s breathing zone, and tasks include not only application of chemicals, but sculpting and shaping of the nails to assure a proper fit. Consequently, nail stylists are potentially exposed to both respirable chemicals and dusts. Among the chemicals are acetone, formaldehyde, methylene chloride, methyl ethyl ketone, toluene and xylene. Standalone nail salons have proliferated in the USA over the past couple of decades, and are often small in size, with poor ventilation and crowded conditions, all of which can favor exposure to harmful levels of these chemicals. Prior to 1974, methyl methacrylate was also found in nail products, but was ultimately banned by the US Food and Drug Administration. Ethyl methacrylate, however, is still used and, as was the case with its predecessor, can cause contact dermatitis, asthma exacerbations and allergic conjunctivitis and rhinitis.

With respect to lung malignancy, there is little evidence of an increased risk in cosmetology professionals.

Traffic police constitute a sector of the police force that may be at increased risk of occupationally related respiratory disease, yet studies are few. However, such an association is plausible. In urban areas, vehicular pollution significantly contributes to the degradation of air quality. Traffic generates volatile organic compounds, suspended particulate matter, oxides of sulfur, oxides of nitrogen and carbon monoxide, and contributes to the production of ozone via secondary photochemical reactions. Several respiratory effects from exposure to air pollutants can occur following exposure to these contaminated air environments, ranging from nonspecific respiratory symptoms such as acute and chronic respiratory tract irritation, cough and dyspnea, to aggravation of asthma, chronic obstructive pulmonary disease and other chronic respiratory disorders. This is likely to occur most often in developing countries, where very high levels of air pollution can occur in urban settings on a regular basis.

The main causes of fatalities among firefighters include sudden cardiac death, typically from myocardial infarction or arrhythmias, followed by motor vehicle accidents and asphyxiation for volunteer and career firefighters, respectively. Toxic gases, rather than heat and flame, are the most common agents of death in a fire. This has been well established since the Cleveland Clinic and Boston Coconut Grove fires of 1929 and 1943, respectively. In both incidents, large numbers of people perished, and yet few were actually burned. During a fire incident, firefighters are potentially exposed to a number of agents capable of causing acute respiratory illness, including asphyxiating gases and aerosols, acrolein, benzene, carbon monoxide, formaldehyde, glutaraldehyde, hydrogen cyanide, nitrogen dioxide, particulates, sulfur dioxide, smoke and other nonspecific combustion and pyrolysis products. Plastics pyrolysis products contain many of the same toxic and reactive species found in ‘fresh’ smoke, as well as particulates capable of acting as carriers of other toxic gases deep into the lung. Personal sampling in firefighters has found carbon monoxide and acrolein to be present at dangerous levels in a large proportion of fires. In more than 50% of fires, acrolein exposures can be at or above occupational short-term exposure limits; concentrations over immediately dangerous to life and health level can occur in up to 10% of incidents. Acrolein can cause rapid development of pulmonary edema at concentrations as low as 10 ppm.

In addition to immediate life-threatening respiratory injury associated with acute smoke inhalation, other respiratory complaints among firefighters, despite wearing self-contained breathing apparatuses (SCBAs) or other forms of respiratory protection, are common. Among these are new-onset asthma and chronic respiratory symptoms, including dyspnea, nasal catarrh, sinusitis and hoarseness. With respect to long-term decline in lung function, there is less evidence of an adverse effect, with the literature providing conflicting results.

Firefighters in full gear carry a large amount of extra weight, due to their SCBAs, slicker gear, boots, helmets and tools, which can affect both the cardiovascular and respiratory systems by increasing both cardiac work and the work of breathing. Heavier respirators (e.g. a 35 pound SCBA) will result in an increased heart rate and cardiac output for a lesser level of physical demand, and a decrease in maximum work performance. Moreover, thermal stress is added by increases in the temperature of exhaled air inside the mask. This heat load is further aggravated by working in a hot environment, wearing impermeable protective clothing that limits the ability of the body to dissipate heat, and/or engaging in high levels of physical exertion that generate additional body heat. The amount of thermal stress can reach dangerous levels, leading to heat exhaustion, which is not uncommon in firefighters.

‘Overhaul’ is the process whereby firefighters search for and extinguish possible sources of reignition; respiratory protection may not always be worn during this task, thus exposing firefighters to increased concentrations of combustion products, producing both transient declines in spirometric lung function as well as increases in various biomarkers of lung permeability, such as serum Clara cell protein 16 and surfactant-associated protein A levels.

The aftermath of the September 11 World Trade Center disaster resulted in a large humanitarian rescue and recovery effort that lasted for months. Among those most involved in these operations were New York City firefighters and policemen. Exposures to smoke, dust and chemical mixtures were of much higher magnitude than previously recorded. Air sampling performed at the time demonstrated a predominance of coarse particulate dusts (95%), containing cement, glass, asbestos, lead, polycyclic aromatic hydrocarbons, polychlorinated furans, dioxins and polychlorinated biphenyls; the high alkalinity (pH > 9.0) of the dust was another important feature. Arrival time at Ground Zero and job title (special operations command firefighters vs other responding firefighters) were associated with increased levels of various chemical metabolites in biological specimens. Inflammatory changes in sputum of the firefighters were also documented. There has been close surveillance, with periodic medical evaluations, of firefighters, police and other rescue and recovery workers over the past several years. Large proportions of these workers, in some cases approaching 70%, have reported persistent upper and lower respiratory symptoms, appearing within the first several weeks of exposure. Declines in lung function, increased bronchial hyper-responsiveness, reactive upper airways dysfunction, gastroesophageal reflux and some cases of parenchymal inflammatory disease, as well as cases of new-onset asthma, suggestive of irritant-induced asthma, have been reported as well. Risk factors predicting abnormal lung function included initial arrival time at the site, duration at the site, and presence of persistent respiratory symptoms.

Interestingly, a few studies have examined possible associations between firefighting and sarcoidosis, although the biological plausibility of such an association is not well established. Nonetheless, in 1985, the New York City Fire Department began a surveillance program for biopsy-proven sarcoidosis. By 1998, the average annual incidence of pulmonary sarcoidosis was 12.9 cases per 100,000 among firefighters, compared with no cases among a comparison group of emergency medical services healthcare workers. Following the collapse of the World Trade Center towers, the incidence of sarcoidosis and ‘sarcoid-like’ granulomatous pulmonary disease increased in the subsequent first (86/10⁵) and fourth (22/10⁵) years, in comparison an average incidence of 15/10⁵ in the 15 preceding years.

There is no consistent evidence that firefighters are at an increased risk of developing cancer.

Baker’s asthma is one of the best known and described forms of occupational asthma, and one of the leading causes in countries where this type of information is tracked. It is an IgE-associated reaction in which demonstration of sensitization to bakery allergens is a central component of the diagnosis, together with documentation of work-related symptoms and lung function variability. The most common causal agents for baker’s asthma are found in wheat, rye and barley flour, and enzymes, primarily fungal alphaamylase. Sensitization among bakers increases with duration in the trade, from around 4% after one year in the apprenticeship to 9% after two years.

In developed nations, changes in the location of traditional bakeries may be affecting the distribution of disease. Thus, in recent years, stand-alone bakeries have been replaced by bakeries inside supermarkets and larger establishments. In coming years, it will be important to see if this change affects the pattern of baker’s asthma and allows the implementation of appropriate workplace controls.

Eating and drinking establishment workers are exposed to high levels of second-hand smoke, up to 2-fold higher than those in office settings, while levels in bars can be over 6-fold higher. Increasingly, smoking ordinances and bans are being implemented in public places in many countries. However, restaurants and bars are exempted in some countries. Despite concerns by establishment owners that smoking bans would adversely affect their business, this has mainly been found only in tobacco industryfunded studies. Instead, there is good evidence that smoking bans have led to significant reductions of exposure to environmental tobacco smoke. In as little as one year after implementing a ban, improvements in forced vital capacity and peak expiratory flow values, together with a decrease in nonspecific respiratory symptoms (e.g. daily cough, phlegm production, rhinorrhea and throat soreness) have been observed.

Janitors and professional cleaners, in both domestic and industrial settings, form a large part of the workforce in most countries. In 2006, approximately 5.4 million persons were employed in the USA in cleaning and building service occupations, with another 746,000 working in private home service-related occupations, i.e. approximately 3% of the total workforce. This is likely to be an underestimate since many workers employed in private households may be undocumented. Distribution by gender is quite different, with males representing slightly over 50% of those working in commercial and industrial settings, whereas women make up 95% of those employed in private households. Wages are low, and access to healthcare is limited. Cleaners perform various tasks, including cleaning surfaces, toilets, carpets and sinks, stripping and waxing floors, and washing windows. These tasks usually involve use of different cleaning products, sometimes in combination. Active components in cleaning products include solvents (e.g. acetone, ammonia, ethanol and pine oil), alkalis (especially bleach), surfactants (e.g. quaternary ammonium chlorides), builders (e.g. sodium EDTA and acetic acid), enzymes (e.g. amylase and proteinase) and disinfectants (e.g. glutaraldehyde, and dialkyl and dimethyl ammonium chlorides). Most are volatilized during cleaning tasks, reaching the breathing zone of unprotected workers, and include both respiratory irritants and sensitizers. Method of application is likely to be important with regards to airborne exposure potential, e.g. sprays vs application with a cloth onto a surface. Inhalation of inappropriately mixed cleaning agents (e.g. bleach and ammonia) can be particularly hazardous, and constitute a common cause of emergency center visits and calls to poison centers. Furthermore, cleaners are also exposed to allergen-containing dusts present on furniture, carpets and in the general air environment of the physical locations where they work.

The potential adverse respiratory health effects of work exposure in the cleaning professions have only recently been recognized, especially asthma. The evidence base linking work with cleaning products as a risk factor for asthma is now fairly substantial, largely stemming from population-based surveys and case-control studies from Europe and the USA. As compared with workers who do not routinely use cleaning products, the odds of asthma in cleaners ranges from 1.8 to 2.5 times greater, increasing further among those who reported cleaning kitchens, polishing furniture and using oven sprays and polishes. Both upper and lower respiratory tract symptoms occur commonly in association with specific cleaning tasks, including dusting, vacuuming and cleaning bathrooms and kitchens. Symptoms include sneezing, runny nose, nasal congestion, nasal burning, dry cough, productive cough, wheeze, chest tightness and dyspnea. Among the chemical products producing such symptoms are diluted bleach, degreasing sprays, ammonia and air fresheners.

Findings of an increased prevalence of new-onset asthma and symptoms of bronchial hyper-responsiveness among HCWs, such as nurses, who are more likely to adopt a bystander role, suggest that not only professionals who directly apply cleaning products are at risk of respiratory airway disease. Additionally, when one factors in the millions of unpaid spouses who clean in their own homes, exposure to cleaning products as a risk factor for both upper and lower airway syndromes may prove to be substantial.

As a nation develops economically, service-based industries employ an increasing proportion of its workers. In the most developed countries, this proportion easily exceeds 50%. Specific occupations in the services sector are at risk of exposures leading to adverse respiratory effects, mostly involving the upper and/or lower airways. Among the at-risk occupations are healthcare professionals, persons caring for animals, traffic police and firefighters, bakery workers, employees in restaurants and bars, and professional cleaners. Although in many cases causes are well established and have led to implementation of controls, the presence of numerous chemicals with sensitizing or irritant potential (e.g. cleaners), lack of resources (e.g. tuberculosis among healthcare workers in developing countries), changes in traditional work locations (e.g. bakeries) and unanticipated exposure incidents (e.g. the September 11 attack on the World Trade Center) indicate that risks continue to exist in this sector, warranting heightened vigilance.

Further reading

Arif, A.A., Delclos, G.L., Whitehead, L.W. et al. (2003) Occupational exposures associated with work-related asthma and work-related wheezing among U.S. workers. Am. J. Ind. Med. 44: 368-376.

Brant, A. (2007) Baker’s asthma. Curr. Opin. Allergy Clin. Immunol. 7: 152-155.

Buyantseva, L.V., Tulchinsky, M., Kapalka, G.M. et al. (2007) Evolution of lower respiratory symptoms in New York police officers after 9/11: a prospective longitudinal study. J. Occup. Environ. Med. 49: 310-317.

Delclos, G.L., Gimeno, D., Arif, A.A. et al. (2007) Occupational risk factors and asthma among health care professionals. Am. J. Respir. Crit. Care Med. 175: 667-675.

Hamann, C.P., Rodgers, P.A., Sullivan, K.M. (2004) Occupational allergens in dentistry. Current Opin. Allergy Clin. Immunol. 4: 403-409.

Kogevinas, M., Zock, J.P., Jarvis, D. et al. (2007) Exposure to substances in the workplace and new-onset asthma, an international prospective population-based study (ECRHS-II). Lancet 370: 336-341.

National Institute for Occupational Safety and Health (NIOSH) (1999) Controlling Chemical Hazards During the Application of Artificial Fingernails. US DHHS, publication no. 99-112.

Nienhaus, A., Skudlik, C., Seidler, A. (2005) Work-related accidents and occupational diseases in veterinarians and their staff. Int. Arch. Occup. Environ. Health 78: 230-238.

Skogstad, M., KjÌrheim, K., Fladseth, G. et al. (2006) Cross shift changes in lung function among bar and restaurant workers before and after implementation of a smoking ban. Occup. Environ. Med. 63: 482-487.