Table 2 Rate of decline in FEV₁. Studies are ordered by population type and year of publication. Values are means (SD), medians [IQR] or means [95% CI]

 Peters et al. 1974 [37]

Firefighters

1

2

Δvalue/Δtime

3.578

Mix [NR]

-68.2

Significant difference in FEV₁ changes when stratified by exposure (no. of fires fought in previous 12 months): FEV₁ change (mL/yr): 1–40 fires; − 49, 41–99 fires; −71, ≥100 fires; −109 (p < 0.02).

No apparent differences in age, height, smoking habits, race when compared between groups stratified by exposure.

 Musk et al. 1977 [35]

Firefighters

3.4

3

Δvalue/Δtime^a

3.62

Mix [NR]

-30

No significant relationship between FEV₁ change and estimated (by fire department records or firefighter) fires fought in previous 12 months. No relationship between FEV₁ change and fires fought when stratified by age, smoking status or service time. Significantly greater FEV₁ decline in firefighters who fought fewer fires in 1973 vs. 1970 than those who fought the same number or more (p < 0.05). Firefighters who fought no fires experienced greatest decline.

No significant relationship between FEV₁ decline and age.

 Musk et al. 1977 [36]

Retired firefighters

4.4

3

Δvalue/Δtime^a

3.19

Nev

For

Cur

Total: Mix [31]

-30

-30

-100* (p < .05 relative to Nev & For)

Total: -50

No significant difference between FEV₁ change of retired firefighters who were active vs inactive (during 1970) prior to retirement. No significant difference in FEV₁ decline when stratified by years of service.

Greater FEV₁ decline in current vs never or ex-smokers (p < .05).

 Musk et al. 1982 [34]

Firefighters

6

2

Δvalue/Δtime^b

3.68 (0.64)

Nev

For

Cur

Cur/For cigar/pipe

Total: Mix [NR]

-33 (44)

-33 (39)

-47 (45)

-31 (44)

Total: -36

Amongst active firefighters; no relationship between FEV₁ decline and either calculated^c or estimated^d number of fires fought in previous 12 months

Inactive (fought no fires in previous 12 months) firefighters tended to have a higher rate of FEV₁ decline than active firefighters (significance not tested).

No correlation between change in FEV₁, or FVC between 1970 and 1976 and the initial level of FEV₁ in 1970 (r = 0.10 for FEV₁).

No relationship between annual change in FEV₁ and the stated tendency of the subjects to voluntarily wear protective breathing apparatus.

 Douglas et al. 1985 [31]

Firefighters

1

2

NR

NS

Mix [NR]

-92

Only cross-sectional effect of exposure reported.

Change in FEV₁ unrelated to service time, or to absence from work after exposure to smoke.

Statistically significant greater FEV₁ decline among current smokers (Actual difference and p value not reported).

 Tepper et al. 1991 [33]

Repeating^e firefighters (n = 492)

6–10

2

Δvalue/Δtime

3.83 (0.68)

Mix [Cur, 50]

-24.99 (61.23)*

Significantly greater adjusted (multiple linear regresion^{2, 4, 14, 15, 18, 21}) FEV₁ decline in active vs inactive repeating^e firefighters (− 29.33 vs 0.30 mL/yr) (p < .01), but not non-repeaters^e. Non-significant trend of greater adjusted FEV₁ decline in those who reported ever vs never being exposed to ammonia (− 38.82 vs − 23.16 mL/yr) (p = .06) (amongst all firefighters), but no differences based on past chlorine exposure.

No significant relationship between adjusted FEV₁ decline and years spent in exposed jobs before baseline or number of firefighting responses before baseline.

Greater adjusted FEV₁ decline in those who reported never vs ever using a mask while extinguishing fires, but only significant in non-repeaters^e (− 68.44 vs − 30.90 mL/yr) (p = .01). No significant difference in FEV₁ decline based on mask-use during fire overhaul.

Non-repeating^e firefighters (n = 136)

Mix [Cur, 45]

-34.79 (40.00)*

(p = .03)

 Kales et al. 1997 [38]

HAZMAT firefighters

2.58

2

Δvalue/Δtime

NR

Nev

Cur or For

Total: Mix [Ev, 38]

-40.69^f

-68.6^f

(p = .27)

Total: -51

NR

No significant difference in FEV₁ changes between smokers and former/current smokers, or between younger (≤35 years) and older (> 35 years) firefighters.

 Burgess et al. 2004 [40]

Firefighters

≥5

≥6

Simple linear regression

4.27 (0.66)

Mix [Ev, 28]

-34 (43)

NR

Rate of FEV₁ decline increased significantly with baseline FEV₁ (p < .001) and age (relative to reference group ≤30 yrs. of age: 31–40 yrs. (p = .006), 41–50 yrs. and > 50 (p < .001), but no significant effect of smoking (never vs ever) or sex. TT genotype at IL-10 SNP 1668 was associated with a significantly lower rate of FEV₁ decline, compared to the AA genotype (p = 0.023) (based on a subsample of firefighters with IL-10 SNP information; n = 379) (ANOVA^{2, 3, 17, 18}).

 Josyula et al. 2007 [41]

Firefighters

7

≥4

Simple linear regression

4.16 (0.70)

Mix [For; 18, Ev; 12] (100% CurNS)

-33 (59)

NR

Greater baseline FEV₁ and asthma associated with greater FEV₁ decline (p = .002 and p = .0023, respectively). Weight gain was close to being significantly associated with FEV₁ decline (p = .05). No significant relationship between FEV₁ change and gender, baseline age, height, baseline body mass index, race or smoking status. Mean FEV₁ decline significantly lower in those possessing the TT genotype of the IL-10 (819) polymorphism [n = 3, − 125 (27) mL/yr], vs. the CC [n = 33, − 20 (61)] or CT genotypes [n = 31, − 38 (51)] (p = .009). Increased IL-1RA associated with slower FEV₁ decline (p = .025) (Multiple regression^{1, 2, 3, 13, 17, 18, 22}).

 Yucesoy et al. 2008 [42]

Firefighters

M: 11.8 (2.5)

F: 11.6 (2.3)

M: 10.3 (2.1)

F: 10.3 (2.2)

Simple linear regression

M: 4.39 (0.63)

F: 3.60 (0.43)

M: Mix [19.8]

F: Mix [30]

M: -34 (27)

F: -38 (20)

Total: -34 (30)

NR

Lower rate of FEV₁ decline in the presence of the TGFβ1–509 TT genotype (p = .043) (multiple linear regression^{2, 3, 13, 16, 17, 18, 25}). Carrying an A allele at TNFα-308 (p = 0.010) and GG genotype at TNFα-238 (p = 0.028) was associated with a more rapid rate of FEV₁ decline. The TNFα-308A/− 238G haplotype was associated with an increased rate of decline compared with the other haplotypes. Ever-smokers had a significantly greater rate of decline (− 4.7 mL/yr) compared with never smokers (p = .042). FEV₁ changes not significantly different by race or gender.

 Sparrow et al. 1982 [10]

Firefighters^g

5

2

Δvalue/Δtime

4.08 (0.073)

(Nev)

Nev

For

Cur

-81.2 (19.2)

-68.2 (8.7)

-77.9 (8.5)

Non-significant trend of greater FEV₁ decline (additional 12 ml/yr) in firefighters vs controls (p = .054). No significant relationship between years of employment and FEV₁ decline.

Greater FEV₁ decline in current vs never smokers (p < .001), adjusted for firefighting status. Non-significant difference in FEV₁ decline in former smokers vs never (p = .530). Greater age and baseline FEV₁ as well as lesser height were associated with greater rates of FEV₁ decline (p < .001).

GP controls^g

3.93 (0.029)

(Nev)

Nev

For

Cur

-64.1 (3.9)

-62.8 (3.7)

-65.2 (3.2)

 Horsfield et al. 1988 [32]

Firefighters

1–4

4–8

Simple linear regression

NR

Nev

For

Cur

-66.5* (p < .05)

-53.8* (p < .05)

-70.5

Total: -65.4* (p < .01)

Compared to GP CON, the rate of change in FEV₁ was significantly less negative in all firefighters (p < .01) and never and former smoking firefighters (p < .05).

No significant difference in rate of change in FEV₁ between firefighting smoking groups.

GP controls

Nev

-100.3*

(All p values relative to GP controls)

 Hnizdo 2012 [43]

Firefighters

8–11

≥4

Simple linear regression

4.39 (0.64)

Mix [≈5]

-39.6 (29.5)

NR

NR

Paper-pulp mill workers

4.33 (0.60)

4.11 (0.68)

Nev

Mix [60]

-34.3 (33.5)

-45.2 (32.2)^h

Construction workers

4.10 (0.7)

Mix [NR]

-48.7 (50.1)

 Aldrich et al. 2013 [9]

Firefighters

5

5

Linear mixed effects modelling (5^{2, 8, 13, 21, 22})

4.4 (0.6)

Nev

Nev

Ev

-344.8 [CI, -347.3 to -342.3]ⁱ

-337.6 [CI, -340.4 to -334.8]

-336 [CI, -341 to -332]

No significant difference in FEV₁ change between Firefighters and controls: average difference (Fire - EMS) 0.2 mL/yr. (CI -9.2 to 9.6).

Weight gain and service time independently associated with increased rate of FEV₁ decline (p value not reported).No difference in FEV₁ decline in ever vs never smokers.

EMS control

3.9 (0.7)

Nev

Nev

Ev

-44.6 [CI, -53.2 to -35.5]ⁱ

-33.8 [CI, -43.7 to -23.8]

-29 [CI, -38 to -19]

 Schermer et al. 2013 [8]

Firefighters

2.9 (0.3)

2

Δvalue/Δtime

4.51 (0.66)

CurNS

+ 15.6 (104.0)^j

The difference in the annual change in FEV₁ between the younger and older age categories differed between the firefighters and controls (interaction term stage cohort age category: p = .040). Firefighters had a lower odds of accelerated FEV₁ decline compared with population controls (OR = 0.60, CI 0.44–0.83; p = .002) (Logistic regression analysis^{2, 9, 18}).

Firefighters who reported never or rarely using their respiratory protection during fire knockdown had a higher odds of accelerated FEV₁ decline compared with those who used it often or frequently (OR = 2.20, CI 1.02–4.74; p = .044)

GP controls

3.5 (1.1)

3.73 (0.70)

CurNS

-27.8 (78.6)^j

 Choi et al. 2014 [30]

Firefighters

3

2

NR

NR

Mix [Cur, 11.8]*

-110*

No significant difference between active and non-active firefighters (RMANOVA^{2, 7, 8, 12, 18}). FEV₁ decline was significantly greater in firefighters compared to non-firefighters (p < .001).

NR

Non-firefighter controls

Mix [Cur, 42.9]*

(p < .001)

-67*

(p < .01)

 Unger et al. 1980 [39]

Exposed firefighters

Post exposure: 1.5

2

ROD not reported^f

Post exposure: 4.003 (0.633)

Mix [NR]

-81.3^f

NR. No pre-exposure measurements, no comparison to un-exposed controls.

NR

 Banauch et al. 2006 [44]

9/11-exposed FDNY firefighters & EMS workers

Pre 9/11: 5

Post 9/11: 1

1–7

Linear random-effects modelling (5^{2, 8, 13, 17, 18})

4.30 [IQR 3.80–4.80]

Mix [29]

Pre-9/11 (Fire & EMS)-31

Post-9/11: Fire; -383 ml [CI, -393 to -374]

EMS; -319 ml [CI, -340 to -299]

Significant difference in pre and post-9/11 FEV₁, within arrival time–based exposure groups (p < .001). Trans-9/11 FEV₁ decline by exposure group: high-intensity exposure; − 388 ml (CI, − 370 to − 406), intermediate-intensity; − 372 ml (CI, − 363 to − 381), low-intensity; − 357 ml (CI, − 339 to − 374 ml) (Significant linear trend in exposure intensity–response, p = .048). Significant differences in trans 9/11 loss, according to work assignment (Fire vs EMS) (p < .001).

Significant difference in reported ‘frequent’ use of protective mask on arrival day between exposure groups (p < .001); no observed protective effect of mask use frequency on adjusted average post 9/11 FEV₁.

 Aldrich et al. 2010 [45]

9/11-exposed firefighters

Post 9/11: 6.1 [IQR, 5.2–6.6]*

5 [IQR, 4–7]

Linear mixed models (4^{2, 8, 13, 17})

Nev: 4.54^k

For: 4.48^k

Cur: 4.46^k

Nev

For^l

Cur^m

Post-9/11

-26 [CI, -31 to -20]*

-38^k

-43^k

FEV₁ decline 6 months post 9/11: FIRE; − 355 ml [CI, − 352 to − 359], EMS; − 272 ml [CI, − 268 to − 276] (p = 0.004). FEV₁ decline 12 months post 9/11: FIRE; − 439 ml [CI, − 408 to − 471], EMS; − 267 ml [CI, − 263 to − 271] (p = 0.003).

Firefighters, but not EMS workers, with heaviest dust exposure had significantly larger declines of − 371 ml (CI, − 362 to − 380) during the first 6 months and − 585 ml (CI, − 515 to − 656) during the first year than did the other members of the cohort.

Last FEV₁ in the final 2 years for workers who had never smoked, there was a non-significant trend toward an association between the number of months of work at the WTC site after 9/11 and the FEV₁ value, a decline of 4 ml per month of work (p = .07).

NR

9/11-exposed EMS workers

6.4 [IQR, 5.9–6.7]*

(p < .001)

Nev: 3.90^k

For: 3.90^k

Cur: 3.80^k

Nev

For^k

Cur^k

-40 [CI,-42 to -38]* (p < .001)

-38^k

-42^k

 Banauch et al. 2010 [48]

9/11-exposed firefighters

Pre-9/11: 3

Post-9/11: 4

2–10

Mixed linear random effects modelling (9^{2, 8, 10, 11, 13, 17, 18, 23, 24})

Pre-9/11

4.19 (0.68)

Mix [NR]

Post 9/11:

No AAT-deficiency: -37 (SE -28 to -45^k) (adjusted)

Average FEV₁ reduction of -370 mL due to 9/11 exposure.

Comparing firefighters with different AAT phenotype combinations: Significantly greater rate of post-9/11 FEV₁ decline in firefighters with mild (− 69 [SE − 41 to -97^k] mL/yr) and moderate (− 147 [SE − 110 to -184^k]) AAT-deficiency compared to normal (p = .011). Significant trend for decline rate acceleration by AAT phenotype combination (p = .003).

Significantly greater rate of post-9/11 FEV₁ decline in Firefighters with Low AAT serum level (− 86 [SE − 66 to -107^k]) vs normal (p = .027).

 Aldrich et al. 2016 [46]

9/11-exposed firefighters

Post 9/11: 12.2 [IQR, 11.6–12.6]^q

9 [IQR, 7–10]

Linear mixed models (5^{2, 8, 13, 17, 21})

Nev: 4.59^k

Forⁿ: 4.61^k

For^o: 4.52^k

For^p: 4.45^k

Cur: 4.55^k

Nev

Forⁿ

For^o

For^p

Cur

Post-9/11:

-26^k

-31^k

-33^k

-37^k

-48^k

Among never smokers, firefighters arriving the morning of September 11 had slightly lower average FEV₁ than lesser exposed firefighters; this difference remained significant during most of follow-up (p < .05 for most 6-monthly time intervals)

Body weight at the time of PFT was associated with FEV₁ (p < .05); for each pound of body mass gained, FEV₁ decline averaged 3.93 mL. FEV₁ change differed significantly by smoking status (p < .001). After first 3 years of follow-up, never smokers had significantly greater FEV₁ than current smokers and former smokers who quit after September 11. During last time interval, FEV₁ significantly greater in non-smokers and those who quit before 9/11 than current or former smokers who quit after 9/11. Firefighters quitting smoking before March 10, 2008, had significantly greater FEV₁ than current smokers during most of the post-September 11 follow-up.

 Aldrich et al. 2016 [47]

9/11-exposed firefighters

Post-9/11: 11.5 (0.5)

Pre-9/11: 1

Post-9/11: 2

Δvalue/Δtime

4.28 (0.67)^q

Mix [Cur 6.4, For 17.9)

Post-9/11:

-32 (unadjusted)-36.78 (adjusted in multiple regression model)

Effect of 9/11 exposure on FEV₁ decline post-9/11 not investigated. Average reduction in FEV₁ across 9/11–399 (468.3) mL.

15.39 mL/year more rapid adjusted^{2, 6, 8, 13, 19, 20} FEV₁ decline in those with BHR at follow-up, compared with those without BHR (p = .0104). Use of steroids associated with a 13.01 mL/year slower rate of decline, compared with those who never used steroids (p = .0197).