Effects of universal masking on Massachusetts healthcare workers' COVID-19 incidence.

BACKGROUND: Healthcare workers (HCWs) and other essential workers are at risk of occupational infection during the COVID-19 pandemic. Several infection control strategies have been implemented. Evidence shows that universal masking can mitigate COVID-19 infection, though existing research is limited by secular trend bias. AIMS: To investigate the effect of hospital universal masking on COVID-19 incidence among HCWs compared to the general population. METHODS: We compared the 7-day average incidence rates between a Massachusetts (USA) healthcare system and Massachusetts residents statewide. The study period was from 17 March (the date of first incident case in the healthcare system) to 6 May (the date Massachusetts implemented public masking). The healthcare system implemented universal masking on 26 March, we allotted a 5-day lag for effect onset and peak COVID-19 incidence in Massachusetts was 20 April. Thus, we categorized 17-31 March as the pre-intervention phase, 1-20 April the intervention phase and 21 April to 6 May the epidemic decline phase. Temporal incidence trends (i.e. 7-day average slopes) were compared using standardized coefficients from linear regression models. RESULTS: The standardized coefficients were similar between the healthcare system and the state in both the pre-intervention and epidemic decline phases. During the intervention phase, the healthcare system's epidemic slope became negative (standardized ß: -0.68, 95% CI: -1.06 to -0.31), while Massachusetts' slope remained positive (standardized ß: 0.99, 95% CI: 0.94 to 1.05). CONCLUSIONS: Universal masking was associated with a decreasing COVID-19 incidence trend among HCWs, while the infection rate continued to rise in the surrounding community.

Recruit fitness and police academy performance: a prospective validation study.

BACKGROUND: Police academies need fit recruits to successfully engage in training activities. In a previous retrospective study, we documented that recruits with poor fitness at entry to the academy had significantly lower graduation rates, and we also suggested evidence-based entry-level fitness recommendations. AIMS: To validate our findings in a prospective cohort of police recruits. METHODS: Recruits entering Massachusetts municipal police academies during 2015-16 were followed prospectively until they dropped out, failed or successfully graduated their academy classes. Entry-level fitness was quantified at the start of each training class using: body composition, push-ups, sit-ups, sit-and-reach and 1.5-mile run time. The primary outcome of interest was the odds of failure (not successfully graduating from an academy). We used logistic regression to assess the probability of not graduating, based on entry-level fitness. RESULTS: On average, successful graduates were leaner and possessed better overall entry-level fitness. After adjusting for age, gender and body mass index, several fitness measures were strongly associated with academy failure: fewer sit-ups completed (OR 9.6 (95% CI 3.5-26.3) (≤15 versus 41-60)); fewer push-ups completed (OR 6.7 (95% CI 2.5-17.5) (≤20 versus 41-60)); and slower run times (OR 18.4 (95% CI 6.8-50.2) (1.5 miles in > 15 min 20 s versus 10 min 37 s to 12 min 33 s)). The prospective study results supported previously suggested minimum entry-level fitness (95% graduation rate) and target (98% graduation rate) recommendations. CONCLUSIONS: Push-ups completed and 1.5-mile run time at police academy entry were successfully validated as predictors of successful academy graduation, while sit-ups were also a strong independent predictor in the prospective study.

Recruit Fitness as a Predictor of Police Academy Graduation.

BACKGROUND: Suboptimal recruit fitness may be a risk factor for poor performance, injury, illness, and lost time during police academy training. AIMS: To assess the probability of successful completion and graduation from a police academy as a function of recruits' baseline fitness levels at the time of academy entry. METHODS: Retrospective study where all available records from recruit training courses held (2006-2012) at all Massachusetts municipal police academies were reviewed and analysed. Entry fitness levels were quantified from the following measures, as recorded at the start of each training class: body composition, push-ups, sit-ups, sit-and-reach, and 1.5-mile run-time. The primary outcome of interest was the odds of not successfully graduating from an academy. We used generalized linear mixed models in order to fit logistic regression models with random intercepts for assessing the probability of not graduating, based on entry-level fitness. The primary analyses were restricted to recruits with complete entry-level fitness data. RESULTS: The fitness measures most strongly associated with academy failure were lesser number of push-ups completed (odds ratio [OR] = 5.2, 95% confidence interval [CI] 2.3-11.7, for 20 versus 41-60 push-ups) and slower run times (OR = 3.8, 95% CI 1.8-7.8, [1.5 mile run time of ≥15'20″] versus [12'33″ to 10'37″]). CONCLUSIONS: Baseline pushups and 1.5-mile run-time showed the best ability to predict successful academy graduation, especially when considered together. Future research should include prospective validation of entry-level fitness as a predictor of subsequent police academy success.

Duty-related risk of sudden cardiac death among young US firefighters.

BACKGROUND: Little is known regarding duty-related risks for sudden cardiac death (SCD) among young firefighters. AIMS: To investigate duty-related SCD among US firefighters aged 45 or younger. METHODS: We collected data on duty-related SCD from the US Fire Administration (USFA) and the US National Institute for Occupational Safety and Health (NIOSH). Two physicians independently reviewed each record. The proportions of time spent by firefighters performing specific duties were estimated from a municipal department, 17 large metropolitan departments and a national database. We estimated the duty-specific relative risks (RRs) and 95% confidence intervals (95% CI) of SCD relative to non-emergency duties based on the observed deaths and the expected average proportions of time per duty. RESULTS: The USFA recorded 205 age-eligible on-duty SCDs between 1996 and 2012; 86 (42%) of these deaths and one additional SCD were investigated by NIOSH (total n = 206). NIOSH was more likely (P < 0.001) to report on SCD associated with physical training (69% of cases were investigated) and fire suppression (57%). Compared with non-emergency duties, the risk of SCD was increased for fire suppression (RR 22.1, 95% CI 14.8-32.9), alarm response (RR 2.6, 95% CI 1.5-4.6), alarm return (RR 4.1, 95% CI 2.7-6.2) and physical training (RR 4.8, 95% CI 3.2-7.2). RRs for SCD were higher among firefighters with a pre-existing history of a cardiac condition. All 16 SCDs associated with alarm response occurred among volunteer firefighters. CONCLUSIONS: The performance of strenuous emergency duties is strongly associated with an increased risk of SCD among young firefighters, particularly among those with a history of cardiovascular disease.

Low fitness is associated with exercise abnormalities among asymptomatic firefighters.

BACKGROUND: Low cardiorespiratory fitness (CRF) has been repeatedly linked to cardiovascular morbidity and mortality, while higher CRF levels are protective. This relationship is likely to be highly relevant in firefighters, who have increased risk of cardiovascular disease (CVD) mortality during strenuous emergencies, which can require prolonged periods of near-maximal heart rates (HR) and high workloads. Abnormalities during maximal stress testing could mark future CVD risk during strenuous duties. AIMS: To determine if low CRF among asymptomatic firefighters is associated with higher risk of electrocardiographic (ECG) and autonomic abnormalities during maximal exercise stress testing and recovery. METHODS: Male career firefighters completed a maximal stress test exercising to volitional exhaustion (mean maximal age-predicted HR achieved 98%, standard deviation (SD) = 6.5). CRF was measured as maximal metabolic equivalents (METS) achieved. Abnormal exercise tests included the following: abnormal HR recovery; chronotropic insufficiency; exaggerated blood pressure response; and ECG abnormalities. The relationship of CRF to stress testing abnormalities was analysed using peak METS categories and peak METS as a continuous variable after adjusting for age, body mass index (BMI) and metabolic syndrome (MetSyn). RESULTS: There were 1149 study participants. CRF was inversely associated with the risk of both ECG and autonomic exercise testing abnormalities before and after adjustment for age, BMI and MetSyn. CONCLUSIONS: Firefighters with lower CRF are significantly more prone to exhibit abnormal stress test parameters, which may indicate higher future risk of cardiovascular events. As such, firefighters with low CRF (≤ 12 METS) should receive cardiovascular risk reduction, including efforts to improve their CRF.

Firefighters' hearing: a comparison with population databases from the International Standards Organization.

We investigated firefighters' hearing relative to general population data to adjust for age-expected hearing loss. For five groups of male firefighters with increasing mean ages, we compared their hearing thresholds at the 50th and 90th percentiles with normative and age- and sex-matched hearing data from the International Standards Organization (databases A and B). At the 50th percentile, from a mean age of 28 to a mean age of 53 years, relative to databases A and B, the firefighters lost an excess of 19 to 23 dB, 20 to 23 dB, and 16 to 19 dB at 3000, 4000, and 6000 Hz, respectively. At the 90th percentile, from a mean age of 28 to a mean age of 53 years, relative to databases A and B, the firefighters lost an excess of 12 to 20 dB, 38 to 44 dB, 41 to 45 dB, and 22 to 28 dB at 2000, 3000, 4000, and 6000 Hz, respectively. The results are consistent with accelerated hearing loss in excess of age-expected loss among the firefighters, especially at or above the 90th percentile.

Prospective study of hepatic, renal, and haematological surveillance in hazardous materials firefighters.

OBJECTIVES: To evaluate possible health effects related to work with hazardous materials as measured by end organ effect markers in a large cohort over about 2 years, and in a subcohort over 5 years. METHODS: Hepatic, renal, and haematological variables were analysed from 1996-98 in hazardous materials firefighters including 288 hazardous materials technicians (81%) and 68 support workers (19%). The same end organ effect markers in a subcohort of the technicians were also analysed (n=35) from 1993-98. Support workers were considered as controls because they are also firefighters, but had a low potential exposure to hazardous materials. RESULTS: During the study period, no serious injuries or exposures were reported. For the end organ effect markers studied, no significant differences were found between technicians and support workers at either year 1 or year 3. After adjustment for a change in laboratory, no significant longitudinal changes were found within groups for any of the markers except for creatinine which decreased for both technicians (p<0.001) and controls (p<0.01). CONCLUSIONS: Health effects related to work are infrequent among hazardous materials technicians. Haematological, hepatic, and renal testing is not required on an annual basis and has limited use in detecting health effects in hazardous materials technicians.

Spirometric surveillance in hazardous materials firefighters: does hazardous materials duty affect lung function?

We analyzed spirometry results for 351 male hazardous materials firefighters from 1996 to 1999 who underwent one or more annual medical surveillance/fitness for duty examinations: 276 (79%) technicians and 75 (21%) support members. Support members had a very limited potential for hazardous materials exposure and served as referents. In cross-sectional comparisons, the technicians' average forced vital capacity and forced expiratory volume in 1 second were either statistically better or not significantly different from that of the support members at all four examinations. Longitudinally, no statistically significant differences were seen for forced vital capacity. The mean percent of predicted forced expiratory volume in 1 second decreased by 3% for technicians (P = 0.029), support controls (P = 0.433), and the total cohort (P = 0.014). Although respiratory irritants are the most common type of exposure in hazardous materials releases, the results suggest that hazardous materials technicians do not lose pulmonary function at a more accelerated rate than support team firefighters.

Correlates of fitness for duty in hazardous materials firefighters.

BACKGROUND AND METHODS: From a statewide medical examination program, we identified firefighters who were deemed unfit for duty by attending physicians (ATTENDING FAIL, n=9) and those who would have been disqualified by the application of selected numerical criteria from the 1997 National Fire Protection Association (NFPA) guidelines (NFPA FAIL, n=27) and criteria from a Medical Workshop (WORK FAIL, n=16). The subjects who were unfit for duty or failed numerical criteria were compared with those who were fit for duty and passed all objective criteria (FIT group, n=302). All subjects were given an overall morbidity rating by a board certified internist. Comparisons on two surrogate measures of fitness, VO(2) max predicted and predicted coronary heart disease (CHD) risk, were also performed. RESULTS: We found a significant tendency towards worse results (e.g. higher blood pressure or lower spirometric function) among the three FAIL groups compared with the FIT group. The FAIL groups shared only a small overlap, however, with the firefighters with the highest morbidity ratings, lowest predicted VO(2) max, and highest CHD risks. Increasing morbidity was associated with higher age, lower spirometric function, lower predicted VO(2) max, increasing cholesterol, greater BMI, and higher predicted 10 year CHD risk. CONCLUSIONS: Although the presence of a single serious or poorly controlled condition may render an individual unfit for safe performance as a firefighter, examination of our cohort suggests that multiple risk factor models or overall clinical assessments are superior means of identifying firefighters with poor health status and increased CHD risk.

Methylene chloride poisoning in a cabinet worker.

More than a million workers are at risk for methylene chloride exposure. Aerosol sprays and paint stripping may also cause significant nonoccupational exposures. After methylene chloride inhalation, significant amounts of carbon monoxide are formed in vivo as a metabolic by-product. Poisoning predominantly affects the central nervous system and results from both carboxyhemoglobin formation and direct solvent-related narcosis. In this report, we describe a case of methylene chloride intoxication probably complicated by exogenous carbon monoxide exposure. The worker's presentation of intermittent headaches was consistent with both methylene chloride intoxication and carbon monoxide poisoning. The exposures and symptoms were corroborated by elevated carboxyhemoglobin saturations and a workplace inspection that documented significant exposures to both methylene chloride and carbon monoxide. When both carbon monoxide and methylene chloride are inhaled, additional carboxyhemoglobin formation is expected. Preventive efforts should include education, air monitoring, and periodic carboxyhemoglobin determinations. Methylene chloride should never be used in enclosed or poorly ventilated areas because of the well-documented dangers of loss of consciousness and death.

Correlates of body mass index in hazardous materials firefighters.

We analyzed results from the medical examinations of 340 hazardous materials (HAZMAT) firefighters and observed the relationships between selected parameters and body mass index (BMI). Heights and weights were available for 98% of the subjects (333 of 340). The mean BMI was 28.9 +/- 4.1 kg/m2. Eighty-seven percent (290 of 333) of subjects were overweight (BMI > or = 25) and 34% (113 of 333) were obese (BMI > or = 30). Two percent (7 of 333) were morbidly obese (BMI > or = 39). For comparison purposes, we divided subjects into low (BMI < 27), medium (BMI 27 to < 30), and high (BMI > or = 30) BMI groups. The results demonstrated adverse associations between increasing BMI and resting blood pressures, forced vital capacity, alanine aminotransferase, aspartate aminotransferase, serum cholesterol, and overall morbidity scores. The high prevalence of overweight and obesity and the associated adverse health effects support the development and implementation of fitness-promotion programs for firefighters.

Lung cancer and occupational risk factors in Greece.

This study estimated the proportion of lung cancer in Greece that was attributable to occupational exposure. Two hundred eighty-two patients with lung cancer and 494 controls were interviewed about their socioeconomic characteristics, sex, age, and occupational, smoking, and residential histories. Each subject was classified as exposed or unexposed to known occupational lung carcinogens. Because of the small number of females exposed, only males were included in the multivariate analyses. When the occupationally exposed subjects were compared with the unexposed subjects and an adjustment for smoking was made, the relative risk for lung cancer was 2.9 (95% confidence interval, 1.95-4.31). If 5% to 10% of the Greek population were occupationally exposed, the attributable risk would be 9.9% to 16.6%, respectively. Occupational exposures conferred an additional risk that was approximately threefold that of smoking alone. Risks increased in a dose-response fashion with increasing cigarette consumption.

Fitness for duty evaluations in hazardous materials firefighters.

We analyzed results from the medical examinations of 340 hazardous materials firefighters and applied various objective standards in simulated fitness for duty determinations. Ten percent had elevated blood pressures, 13% had far visual acuity worse than 20/30 in one or both eyes, and 38% had abnormal audiometry. The strictest standards for resting blood pressure and corrected visual acuity would have failed 2% and 1% of the cohort, respectively. For audiometry, 0%-5% of the cohort would have failed, depending on the hearing requirements set. The strictest hearing standard did not allow for corrective devices so that few failures would be reversible. Visual and audiometric testing and measurement of resting blood pressure all have significant clinical yields. Studies of simulated firefighting are needed to establish minimum hearing requirements and determine whether corrective devices can be worn safely during duty.

Prognostic factors in patients with methanol poisoning.

OBJECTIVE: To identify prognostic factors in methanol poisoning and determine the effect of medical interventions on clinical outcome. METHODS: Retrospective review of all patients treated for methanol poisoning from 1982 through 1992 at The Toronto Hospital. Presenting history, physical examination, results of laboratory tests, medical interventions, and final outcomes after hemodialysis were abstracted. RESULTS: Of 50 patients treated for methanol poisoning, 18 (36%) died, 32 (64%) survived. Seven of the 32 survivors sustained visual sequelae (22%), the remaining 25 (78%) recovered completely. Patients presenting with coma or seizure had 84% (16/19) mortality compared to 6% (2/31) in those without (p < 0.001). Initial arterial pH < 7 was also associated with significantly higher mortality (17/19, 89% vs 1/31, 3%, p < 0.001). There were no differences in time from presentation to dialysis between survivors and fatalities (8.4 +/- 3.6 vs 7.6 +/- 3.5 hours, p = 0.47). The deceased patients had higher mean methanol concentration than the survivors (83 +/- 53 vs 41 +/- 25 mmol/L, p = 0.004). Subgroup analysis of 19 patients presenting with visual symptoms who survived showed prolonged acidosis (5.4 +/- 2.3 vs 3.0 +/- 2.1 hours, p = 0.06) in those with persistent visual sequelae. CONCLUSIONS: Coma or seizure on presentation and severe metabolic acidosis, in particular initial arterial pH < 7, are poor prognostic indicators in methanol poisoning. Survivors presented with lower methanol concentrations. Patients with residual visual sequelae had more prolonged acidosis than those with complete recovery. Future studies will be needed to confirm the effect of correction of acidosis on final clinical outcome.

Injuries caused by hazardous materials accidents.

STUDY OBJECTIVE: To describe exposures that prehospital and ED personnel may encounter as a result of hazardous material incidents. METHODS: Retrospective analysis of hazardous material incident reports from six district hazardous material teams in Massachusetts from their inception through May 1996. RESULTS: The chemicals most frequently involved were various hydrocarbons and corrosive materials. Chlorine derivatives were involved in 18% of all incidents and 23% of all incidents resulting in victims. Victims were produced by 47 of 162 (29%) incidents. Respiratory exposures were the most frequent type of exposure and resulted in the largest number of victims transported to a hospital. Overall 24 of 26 (92%) incidents with chemical exposures resulted in symptomatic victims and 33 of 35 (94%) incidents produced victims requiring hospital transport. Respiratory symptoms were the most frequent, both in the number of incidents where they were observed and the total number of victims with symptoms. CONCLUSION: Multiple victim transport to EDs from a single hazardous material incident is most likely to result from an inhalation exposure to a respiratory irritant. Information from descriptive studies should allow improved preparation for potential hazardous material victims.

Mechanisms of and facility types involved in hazardous materials incidents.

The purpose of this study was to systematically investigate hazardous materials (hazmat) releases and determine the mechanisms of these accidents, and the industries/activities and chemicals involved. We analyzed responses by Massachusetts' six district hazmat teams from their inception through May 1996. Information from incident reports was extracted onto standard coding sheets. The majority of hazardous materials incidents were caused by spills, leaks, or escapes of hazardous materials (76%) and occurred at fixed facilities (80%). Transportation-related accidents accounted for 20% of incidents. Eleven percent of hazardous materials incidents were at schools or health care facilities. Petroleum-derived fuels were involved in over half of transportation-related accidents, and these accounted for the majority of petroleum fuel releases. Chlorine derivatives were involved in 18% of all accidents and were associated with a wide variety of facility types and activities. In conclusion, systematic study of hazardous materials incidents allows the identification of preventable causes of these incidents.

Medical surveillance of hazardous materials response fire fighters: a two-year prospective study.

Hazardous materials releases can cause substantial morbidity and mortality, and an increasing number of communities have developed hazardous materials (HAZMAT) teams to deal with such incidents. Little is known, however, about the health effects of chemical accidents on HAZMAT team participants. Baseline and periodic medical surveillance of all 40 fire fighters from the Metrofire Haz-mat team was conducted in 1992/1993 and 1995, respectively. A database on incidents responded to by the team during the study period was also developed. From June 1990 through April 1995, the team responded to a total of 34 hazardous materials incidents. No injuries to HAZMAT team members were reported. Few biochemical abnormalities were observed, and those that were could not be linked to specific exposures or incidents. Four individuals had abnormal audiometry on both occasions. There was a trend toward a lower percent predicted FEV1 for the entire group on follow-up: 106 +/- 13% vs 105 +/- 12%, P = 0.07. For fire fighters older than age 35 (n = 21), the percent predicted FEV1 was significantly lower at follow-up: 108 +/- 12% vs 106 +/- 14%, P = 0.01. The results suggest significant noise exposure and exposure to pulmonary irritants, which support the use of baseline and periodic audiometry and spirometry. The potential utility of other laboratory testing is also discussed.