Occupational asthma in Vietnam's garment factories is a clinical-practice gap as much as an exposure problem. The evidence for serial peak flow monitoring and shift-related spirometry is decades old, yet routine screening for dust-exposed workers remains uncommon, and clinicians seldom ask asthma patients what they do for a living.

The Cough That Follows Workers Home

Vietnam is among the world's largest garment exporters, with hundreds of thousands of workers in factories around Ho Chi Minh City, Hanoi, and the industrial belts of Dong Nai and Binh Duong. Many spend eight to ten hours a day near cotton, polyester, and blended dusts. A cough that improves on days off and returns on Monday morning is a classic pattern, but it is easily attributed to a cold or to city air.

Occupational asthma is defined as new-onset asthma or the recurrence of quiescent asthma caused by workplace exposure. Symptoms include wheezing, chest tightness, cough, and breathlessness that worsen during shifts and ease away from work. The pattern is subtle enough that workers often accept it as normal. Clinicians, pressed for time, rarely ask about job tasks, ventilation, or the timing of symptoms across the working week.

The result is a condition that is both common and invisible. Factory clinics focus on acute injuries and general illness. District hospitals see the cough but lack an occupational frame. Tertiary respiratory centres can confirm the diagnosis, but few workers reach them, and fewer still return for the serial measurements that would make the case.

The sector's structure compounds the problem. Large export factories with foreign buyers often carry international audit requirements that touch on ventilation and worker welfare, while the smaller subcontractors that feed them operate with thinner margins and less oversight. A worker may move between both types of workplace within a single year, which makes any exposure record fragmentary at best.

What the Evidence Says About Dust

Cotton dust and synthetic fibres are well-recognised triggers of occupational asthma. The mechanisms differ: cotton dust can cause airway inflammation through endotoxin and other contaminants, while some synthetic agents act as sensitizers that provoke an immune response after repeated exposure. Hundreds of agents have been linked to work-related asthma across industries, and garment manufacturing combines several of them in a single dusty room.

The diagnostic standard is not a single test. Serial peak expiratory flow readings taken several times a day over two to four weeks, ideally across both work and rest periods, remain the most practical way to demonstrate work-related variability. A fall in peak flow during working days and recovery on days off supports the diagnosis. Spirometry before and after a shift can add useful information, though a single cross-shift measurement is less reliable than a sustained diary.

None of this requires expensive equipment. Peak flow meters are cheap and portable. The obstacle is organisation: someone has to explain the technique, review the diary, and interpret the pattern. In a factory clinic seeing dozens of workers a day, that time is rarely available. A related piece on this site has argued that asthma care follows coverage rather than the spirometer, and the same logic applies here.

Screening Gaps in Factory Clinics

Pre-employment spirometry is often absent in Vietnamese garment factories, especially smaller subcontractors. Without a baseline, a later decline is hard to attribute to work. Routine surveillance for dust exposure is similarly uncommon. Many factories conduct periodic health checks, but these rarely include lung function testing or a structured occupational history.

Workers have strong incentives not to report symptoms. A diagnosis of occupational asthma can mean reassignment, lost income, or non-renewal of a contract. In a sector where turnover is high and union representation varies, the fear is rational. Factory nurses may know which workers cough through the shift, but they are not positioned to initiate specialist referral without a clear pathway.

Referral pathways to respiratory specialists are unclear even in larger cities. A worker with suspected occupational asthma may be told to see a doctor, but not which one, and not how the visit will be paid for. The gap is not a lack of knowledge among specialists. It is a lack of connection between the factory floor and the clinic that could confirm the diagnosis.

Language and migration add another layer. Many garment workers are internal migrants from rural provinces, and some belong to ethnic minority communities whose first language is not Vietnamese. Explaining a two-week peak flow diary to a worker with limited literacy in the national language is a genuine clinical task, not a clerical one. Pictorial diary sheets and instructions read aloud by a nurse can help, but these adaptations are rarely built into a factory health budget.

Barriers to Diagnosis and Reporting

Access to peak flow meters is limited in primary care. A general practitioner may suspect work-related asthma but have no meter to lend and no easy way to teach a diary. Physicians also receive little training in occupational history. Asking about job tasks, exposures, and symptom timing is a skill, and it is not consistently taught in Vietnamese medical curricula.

Compensation systems for occupational asthma are rarely used. The process can be slow, documentation-heavy, and unfamiliar to both workers and clinicians. Migrant workers, who move between factories and provinces, lose continuity of care and often lack the paperwork to pursue a claim. A related piece on this site describes how community clinics fall off reimbursement lists, and similar structural exclusions leave occupational asthma cases unrecorded.

The trade-off is real. Factory managers point to the cost of surveillance and the risk of losing experienced workers to reassignment. Clinicians point to the cost of missing the diagnosis, which includes preventable disability and avoidable emergency visits. Both concerns are legitimate, and neither has been resolved by policy.

There is also a diagnostic trap that runs the other way. Once a worker carries a label of asthma, whether occupational or not, future employers may treat that label as a reason not to hire. The incentive to stay silent therefore outlasts the original exposure. Any screening programme that does not think through what happens after a positive result risks doing harm to the very workers it intends to protect.

Clinical Practice That Could Close the Gap

Simple questionnaires can identify workers with likely work-related asthma. Questions about cough or wheeze that improve on days off, exposure to dust or fumes, and a history of asthma before employment take a few minutes and can be administered by a factory nurse. A positive screen then triggers a peak flow diary and a referral.

Low-cost peak flow monitoring at home is feasible if the worker is given a meter, a diary sheet, and clear instructions. The diary needs to cover at least two working weeks and one rest period. Collaboration with factory nurses can support recruitment and follow-up, and education for general practitioners on work-related asthma can raise the index of suspicion in primary care. This site has covered how asthma guidelines diverge on rescue inhaler reliance, a reminder that even well-resourced systems struggle with consistent practice.

None of these steps is expensive in isolation. The challenge is coordination: who teaches the diary, who reads it, who refers, and who pays. Small pilot programmes in some provinces have shown that a nurse-led questionnaire plus peak flow monitoring can work, but scaling them requires a policy decision that has not yet been made.

What a Realistic Programme Would Look Like

Picture a mid-sized factory with a few hundred sewing staff and one nurse on shift. A practical surveillance package might run as follows. At hiring, every worker completes a short symptom and exposure questionnaire, and those with existing asthma or persistent cough are flagged for a baseline spirometry session, which could be delivered by a visiting technician or a district hospital on a scheduled day. Each year, the questionnaire is repeated, and any worker reporting work-related patterns is offered a peak flow diary and a referral letter naming a specific respiratory clinic.

The cost drivers are not the meters. They are staff time, training, and the follow-up appointment that actually closes the loop. A programme that hands out meters without a review appointment produces diaries that nobody reads, which is worse than no programme at all because it consumes worker goodwill. The design principle should be that every meter issued has a named person responsible for reading the result and a date on which that reading happens.

Ventilation is the other half of the picture. Local exhaust at dusty tasks, general ventilation, and simple housekeeping reduce the exposure that drives sensitization in the first place. Surveillance without exposure control identifies cases while leaving the cause in place. The two belong together, and in most factories neither is fully present.

Actions for Clinicians and Policymakers

Ask every adult asthma patient about their job, including specific tasks, dust exposure, and whether symptoms improve away from work. A short occupational history at the first visit costs little and can redirect the entire diagnostic pathway.

Provide peak flow diaries for suspected cases, with clear instructions and a follow-up appointment to review the pattern. A meter and a diary sheet are inexpensive compared with the cost of repeated emergency visits.

Train primary care staff in occupational history taking and in the interpretation of serial peak flow readings. Short courses and online modules exist, and they do not require specialist equipment.

Advocate for workplace dust monitoring and for routine spirometry in factories with high dust exposure. Surveillance data can support compensation claims and inform factory-level improvements in ventilation.

Support compensation claims for affected workers by simplifying documentation and providing clear guidance on the process. Migrant workers need continuity of care across provinces, which requires coordination between local health systems.

This article is informational and does not constitute personalised medical advice. Readers with symptoms should consult a qualified clinician.