Case study: work-aggravated asthma

Spirometry can form part of health surveillance for work-aggravated asthma, together with a respiratory questionnaire

Work-aggravated asthma is associated with exposure to respiratory sensitisers, such as flour dust. Angela West and Anne Harriss discuss a case study that gives an overview of the involvement of an OH consultancy engaged to advise on the health of an employee.

Mr C worked with flour and had been diagnosed as suffering from asthma, a long-term respiratory condition characterised by airway inflammatory changes and reduced airflow into and out of the lungs. It is associated with bronchial hyper-responsiveness, resulting in coughing, breathlessness, wheezing and chest tightness (Palmer et al, 2007).

Asthma is an atopic disease underpinned by genetic and environmental factors, which results from harmful immune responses elicited by antigens and is characterised by elevated IgE antibody levels (Spickett, 2013). The IgE antibody is specific to one allergen and triggers the release of histamine and heparin granules from mast cells into interstitial tissue, leading to an airway oedema. This case study involves exposure to flour dust.

Diagnosis and treatment

Guidelines from the British Thoracic Society (BTS, 2014) on the management of asthma highlight that a diagnosis in adults can be made in the presence of the following symptoms:

  • wheeziness, breathlessness, chest tightness and cough;
  • symptoms that worsen at night, in response to exercise, an allergen, or thermal extremes; and
  • cannot be attributed to any other disease process.

Diagnosis could also include the following factors:

  • a history of atopy;
  • a family history of asthma and/or atopy; and
  • a positive response to a histamine challenge (typically exercise induced).

Diagnosis may also include evidence of airway obstruction, reduced vital capacity and forced expiratory volume (FEV), assessed by serial peak flow recordings or spirometry.

The BTS recommends that evaluation of trials of treatments should be taken into account before making a definite diagnosis of asthma. A five-step treatment programme, dependant on symptom severity, commences with a short-acting salbutamol inhaler for those with mild, intermittent asthma, increasing to regular oral and inhaled steroid treatment for those with persistent, poor symptom control. Treatment regimes move up and down these steps according to symptoms.

Occupational asthma is associated with substances inhaled at work of that are of an allergic or irritant nature. Work-aggravated asthma (WAA) is the worsening of a preexisting case of asthma, resulting from inhalation of an agent in the workplace or triggered by temperature changes, or physical stressors. One priority is determining whether or not there has already been a diagnosis made of asthma, regardless of current symptoms or treatment. Hayfever-type symptoms of rhinitis, conjunctivitis, and a persistent cold, with a clear reduction in symptoms during periods away from work, is typical of WAA.

Risks should be considered in employees with worsening asthma and/or work-related asthma symptoms, and be investigated in a similar way to potential occupational asthma. In addition to recording a thorough medical and occupational history, other investigations include serial peak flow measurements and allergy testing (specifically IgE testing if the allergen is of high molecular weight). However, diagnostic process can be difficult, and there is not a single or consensus approach identified.

A joint study by the Health and Safety Executive (HSE) and BTS found that the diagnosis of occupational asthma by 100 general respiratory physicians lacked standardisation, and fell short of evidence-based best practice (HSE, 2007). Clearly, the confirmation of a relationship between work and symptoms aids a definite diagnosis.

Epidemiology of work-aggravated asthma

Occupational factors account for around one in six cases of asthma in working-age adults, and approximately 90% of those are allergen attributable (British Occupational Health Research Foundation, 2010). Seven per cent of the UK adult population have asthma. More than one worker in five with asthma has WAA (Health and Safety Laboratory, 2014). However, appropriate control measures can prevent or improve it.

According to the HSE (2014), although over the past decade there has been an overall decrease in the amount of cases reported of occupational asthma (OA), 132 new cases of OA were reported in 2014. This reporting was completed by THOR-SWORD, the national OH surveillance scheme that collects data from more than 1,000 participating specialist physicians.

Occupations reporting the highest number of new cases of OA include vehicle paint technicians and bakers resulting from isocyanate and flour/grain exposure respectively. Despite statistics from THOR SWORD, the true frequency of OA remains unknown, as only cases serious enough to warrant referral to a chest physician are collated.

Relevant legislation

OA is reportable under Regulation 8 of the Reporting of Injuries, Diseases and Dangerous Occurrences Regulations (RIDDOR) 2013. Those diagnosed with OA can claim Industrial Injures and Disability Benefit (IIDB). Eighty-five new cases of OA were assessed for IIDB in 2013, with an average 141 cases annually over the last decade (HSE Annual Report for Great Britain 2013/14). A claim for OA can be made within 10 years, providing the asthma is work related and the claimant can identify the substance of exposure. HSE sources of guidance available for employers and employees that are particularly relevant to this employee include:

  • HSE G402: Health surveillance for occupational asthma details both higher- and lower-level health surveillance; and
  • HSE FL0: Advice for managers – specifically aimed at bakers and millers.

Employee presentation

Mr C is a 25-year-old employed within a cereal producing plant. He met with OH as part of the company annual health surveillance programme. He completed a respiratory questionnaire describing a history of mild, well-controlled asthma since childhood using a salbutamol inhalor, a short-acting broncho-dilator. He had never smoked cigarettes, and lived in a non-smoking household.

Prior to commencing his current employment six months previously, he typically used his inhaler once each morning as prescribed, and again when playing sports. Over the last two months, he had noticed an increasing need to use his inhaler at work, especially when working in the flour room. He reported a new onset of nasal and eye irritation, which he attributed to hayfever. His inhaler use outside of work remained low.

Spirometry was undertaken and a reduced FEV was noted. Mr C commented that the recording appeared lower than at his last GP check.

Employment summary

Approximately 100 people work at the cereal processing plant. Cereal is processed and packed on-site, and employees rotate around all areas of the production area on a two-weekly basis.

The company employs an OH consultancy to undertake annual respiratory health surveillance. All employees have a higher level of health surveillance, including an OH administered respiratory questionnaire, supplemented with spirometry as described in HSE G402.

Control measures include effective local exhaust ventilation, supplemented with respiratory protective equipment (RPE).

Mr C reported personal compliance with RPE wherever it is required. The surveillance is completed in a block period of two weeks each year, at the company’s request. This never changes, despite an OH recommendation to complete health surveillance on a 14-month basis, as this would take account of seasonal changes.

Case management

Mr C’s symptoms, working practices and required adjustments were reviewed five weeks later. During waking hours, Mr C recorded two-hourly serial peak flow measurements prior to that appointment, regardless of whether or not he was at work. He noted on the chart the area of the plant he had been allocated to that week, the activities being undertaken at the time of the measurement, and any general health changes, including most recent use of his inhaler. In line with best practice guidelines, he recorded the highest of three forced expiratory blows.

Palmer et al (2007) recommend that lung function testing, including spirometry and peak flow measurements, are viewed as only one part of the assessment of fitness for work, as skin prick, radioallergosorbent and immunological response can also aid in making a diagnosis. Of vital importance is a thorough questionnaire, and the one used by the OH professional was taken from the HSE website.

A decision also had to be made as to whether or not Mr C should remain at work as normal prior to his review appointment. Palmer et al advise that consideration should be given to whether or not there is an immediate risk to an employee’s health from workplace hazard exposures.

While Mr C was reporting what could be a pattern of WAA, he had not experienced an acute exacerbation of asthma, so the balance of risk did not indicate an immediate need to remove him from further exposure.

In addition, removing him from the flour room before gathering accurate data such as the peak expiratory flow (PEF) recordings may not provide an accurate picture of symptoms in the serial peak flow measurements.

However, Mr C was advised that should his symptoms become acutely worse, he should report this immediately and seek medical attention. His consent was obtained for the OH employee to contact his manager, explaining preliminary findings and the need for further assessment. His manager was supportive, providing access to a room where he could complete the peak flow measurements in privacy.

In order to gain an accurate view of the working environment, further assessment was taken of the area. The flour room is located away from the other areas of the plant with good hygiene measures in place, which prevented any cross-contamination of flour into other work areas. The room was regularly cleaned and wet-mopped.

Local exhaust ventilation was in good working order and processes were mechanised as far as possible although some processes, such as bag opening and tipping were completed manually. Despite this, there was obvious dust in the environment, and workplace monitoring of exposure limits were completed on a regular basis. Records were also kept of both these and regular risk assessments, in line with the requirements of the Control of Substances Hazardous to Health Regulations (2002).

Mr C attended his appointment as planned and his completed PEF measurements showed a clear pattern of workplace aggravated symptoms. When away from work, these recordings were of a constant, expected level for his age, gender and height, but were significantly reduced when working in the flour room with variability of over 100 l/minute between days in the flour room and other days. Days working in other areas of the plant showed that PEF levels in line with nonworking days. It was also possible to see that Mr C used his salbutamol inhaler more frequently when working in the flour room, than on other days.

Working with flour was an aggravating factor, and so the following options were considered:

  • reduce exposure to flour by working in the flour room less frequently or by permanent exclusion; and
  • question whether or not he should continue to be exposed to flour, instigate a three-month review including spirometry, with ongoing six monthly health surveillance.

Additional recommendations included:

  • pre-appointment health screening, including spirometry, for those working with flour;
  • six-monthly surveillance for all new employees during the first year of employment;
  • six-monthly testing for any employee reporting an increase or new incidence of asthma/other allergic type symptoms; and
  • provision of information to all employees at the start of their employment, including the HSE leaflet “Bakers – time to clear the air!”

Mr C’s employer facilitated permanent redeployment to another area of the plant, without any salary reduction. At his review appointment, Mr C’s spirometry results were much improved, he reported a gradual reduced inhaler usage, and was now back to his usual once a day use. The associated symptoms of nasal and eye irritation had also been resolved.

The company also actioned the other recommendations, including introducing a system of pre-appointment health screening, using a paper-based questionnaire for all employees, regardless of their role within the company. The questionnaire follows guidance of the Equality Act 2010, with the two questions being designed to identify employees who may require adjustments to their role or place of work, enabling them to fulfill the role for which they have applied.

In addition, employees to be placed in the flour room complete a respiratory questionnaire and undergo spirometry within four weeks of commencing their role. Since Mr C’s referral, no further cases of WAA have been identified.

References

British Occupational Health Research Foundation (2010). “Occupational asthma, a guide for employers, workers and their representatives”.

British Thoracic Society (2014). “British guideline on the management of asthma”. London: British Thoracic Society.

Health and Safety Laboratory (2007). “Joint study of UK medical secondary care provision for occupational lung disease”. London: HSE.

Health and Safety Laboratory (2014). “Work aggravated asthma: a review of reviews”. London: HSE.

HSE (2014). Health and Safety Statistics, Annual Report for Great Britain. London: HSE.

HSE (2014). “Occupational asthma in Great Britain 2014”, London: HSE

Palmer K, Cox R and Brown I (2007). Fitness for work the medical aspects. Fourth edition. Oxford: Oxford University Press.

Spickett G (2013). Oxford Handbook of clinical immunology and allergy. Third edition. Oxford: Oxford University Press.

Additional reading

Balder B, Lindholm N, Whagen O, Palmqist M, Plaschke P, Tunsater A, Toren K (1998). “Predictors of self-assessed work ability among subjects with recent-onset asthma”. Respiratory Medicine 92, pp.729-734.

Barber C, Naylor S, Bradshaw L, Francis M, Harris-Roberts J, Rawbone R, Curran A, Fishwick D (2007). “Approaches to the diagnosis and management of occupational asthma amongst UK respiratory physicians”. Respiratory Medicine 101, pp.1,903-1,908.

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