Background Occupational asthma is an avoidable form of asthma. In Finland, the diagnosis of occupational asthma entitles substantial compensation to the employee. The diagnostics are based on symptoms, exposure assessment, allergologic investigations, follow-up of peak expiratory flow (PEF) at work and at home and, in many cases, specific challenge tests.
Objective To study the causative agents of occupational asthma in Finland.
Methods The causative agents and the numbers of new occupational asthma cases notified to the Finnish Register of Occupational Diseases (FROD) during 1986–2002 are reported.
Results The number of occupational asthma cases increased from 1986 until 1995, after which a downward trend, stabilizing during the last few years, has been observed. The majority of the cases (59%) in the beginning of the period (1986–1990) were associated with agriculture, but the percentage has fallen thereafter (42% of the cases in 1998–2002) along with the fall in the total number of cases. Since 1995, indoor moulds from water-damaged buildings have caused an increasing number of cases and have become the most important causative agents (0.5% cases, in 1986–1990 and 18% of the cases in 1998–2002). Chemicals have caused 10–30% of the cases, a decreasing number since 1990. The most important chemicals causing occupational asthma have been diisocyanates and welding fumes, followed by hairdressing chemicals and formaldehyde.
Conclusions The number of occupational asthma cases in Finland reached its height in the mid-1990s. The decrease in the number of total cases is because of the decrease in agriculture-associated cases, reflecting the number of employees in agriculture-associated occupations, which has greatly decreased since Finland joined the EU in 1995. An epidemic of mould-induced asthma, affecting mostly white-collar employees working in moisture-damaged buildings, has taken place since 1995.