The organized sheet metal trade formed in 1888 as the Tin, Sheet Iron and Cornice Workers’ International Association, later renamed the Sheet Metal Workers International Association (SMWIA). In 2008 SMWIA merged with the United Transportation Union (UTU) to form the International Association of Sheet Metal, Air, Rail and Transportation Workers (SMART), the trade’s current international union. Throughout the 20th century, SMWIA members fabricated and installed the ductwork, air handlers, exhaust hoods, breeching, stacks, and industrial ventilation systems that heated, cooled, and ventilated virtually every commercial, institutional, industrial, and marine building in the United States.
The asbestos era
From roughly 1920 through the late 1970s, sheet metal workers allegedly encountered asbestos in three converging streams on every HVAC installation. First, the ductwork itself: asbestos-cement duct board (rigid panels cut, tapped, and screwed together for low-pressure supply and return duct runs) and asbestos-fabric duct lagging (wrapped over sheet metal duct for thermal and acoustic control). Second, the equipment they connected the ductwork to: air handlers, fan-coil units, cooling towers, and industrial exhaust systems that allegedly used asbestos-cement drain pans, asbestos-fabric expansion joints, asbestos gasket sets, and asbestos drift eliminators. Third, and often most consequentially, the sprayed asbestos fireproofing applied to structural steel overhead — SMWIA members worked directly beneath sprayed Monokote, Cafco Blaze-Shield, and competitor fireproofings in the ceiling plenum where ductwork was hung, allegedly inhaling fiber that fell as they cut hangers and drilled overhead.
The trade did not choose these materials. Members were dispatched to jobsites where architects and mechanical engineers specified asbestos-cement duct board, where structural specifications called for sprayed asbestos fireproofing on the steel, and where equipment manufacturers factory-installed asbestos-fabric gaskets and expansion joints in air handlers arriving at the loading dock. Sheet metal workers installed what the drawings called for, in the conditions the construction site provided — often working overhead in unventilated ceiling plenums where fiber released from cutting, tapping, and drilling had nowhere to go.
Federal recognition and the EPA fireproofing ban
Federal occupational-health research through the 1960s and 1970s identified sheet metal workers as one of the construction trades with elevated mesothelioma incidence. Studies of sheet metal cohorts documented mesothelioma rates well above the general-population baseline, driven by the trade’s daily handling of asbestos-cement duct board and the pervasive overhead exposure to sprayed asbestos fireproofing in commercial high-rise construction.
The EPA banned sprayed asbestos fireproofing in 1973, and by the late 1970s asbestos-cement duct board was being phased out of new HVAC specifications. But the disease pipeline — driven by the 20-to-50-year latency between asbestos exposure and mesothelioma diagnosis — continued, and continues today, for SMWIA members whose careers fell within the asbestos era.
What the trade did
Through the asbestos era, sheet metal workers were dispatched to four broad categories of work where asbestos was allegedly encountered:
- New construction HVAC installation — cutting and installing asbestos-cement duct board, hanging sheet metal ductwork through overhead sprayed asbestos fireproofing, and connecting to air handlers with factory-installed asbestos gaskets
- Commercial retrofit and tenant fit-out — cutting into existing asbestos-cement duct board, disturbing sprayed fireproofing on structural steel in the ceiling plenum, and modifying existing asbestos-lagged ductwork
- Industrial process ventilation — installing exhaust hoods, breeching, stacks, and industrial ductwork at refineries, chemical plants, steel mills, and food processing facilities, where allegedly asbestos-fabric lagging and asbestos-cement components were standard
- Service and repair — cutting, patching, and modifying installed HVAC systems, which allegedly disturbed asbestos-cement duct board and asbestos-fabric lagging installed decades earlier
Rip-out and demolition of pre-1980 HVAC systems — particularly during commercial building renovations from the 1980s onward — allegedly produced some of the highest-fiber-release exposures for sheet metal workers, as decades-old asbestos-cement duct board was cut apart with saws and asbestos-lagged ductwork was removed section by section.
Allied trades
SMWIA members worked alongside several allied crafts that share parts of the asbestos exposure history:
- Heat & Frost Insulators (HFIAW) — applying pipe covering and block insulation on the same mechanical rooms and above the same ceilings
- Pipefitters / Steamfitters (UA) — running steam, chilled water, and condensate lines through the same ceiling plenums
- Boilermakers (IBB) — fabricating the boilers and industrial exhaust stacks that sheet metal workers connected breeching to
- Bricklayers (BAC) — the refractory bricklayers who lined boilers and industrial furnaces vented by SMWIA breeching
- Structural iron workers — erecting the structural steel that was sprayed with asbestos fireproofing before ductwork was hung
All of these trades have documented mesothelioma incidence above the general population. Sheet metal workers are particularly affected in commercial high-rise construction — the industry sector where sprayed asbestos fireproofing was most extensively specified.
Today
The trade today has largely transitioned to non-asbestos materials — galvanized sheet metal ductwork with fiberglass duct liner, factory-insulated flex duct, and non-asbestos gasket sets. Members who entered the apprenticeship in the late 1980s or later worked through a substantially safer materials regime. But the disease tail of the asbestos era continues. SMWIA members who entered the trade in the 1950s, 1960s, and 1970s — now in their 60s, 70s, and 80s — are the population now being diagnosed with mesothelioma and other asbestos-related diseases at the highest rates.
This site exists to document that history and, where applicable, to help affected members and families navigate the claims process under the asbestos bankruptcy trusts and state-specific litigation frameworks that compensate workers and survivors of asbestos exposure.
Free, confidential case evaluation: Speak with O’Brien Law Firm — (314) 237-3332
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