Introduction Noise exposing is the main reason of NIHL. But even exposed to same noise and time effects are totally different, some workers have normal hearing level, some have minor loss and other may have severe loss. So NIHL is complicated and related to not only working environment but also individual and genetic factors. Individual factors include specific character, behaviour and habits. The study discussed individual factors interfering with NIHL and presented advice.

Methods A retrospective cohort study was conducted among noise-exposed-workers in railway-transport-equipment-manufacturing-industry in Beijing in 2016. Occupational history and individual factors were collected. Data were analysed using SPSS with binary logistic regression(backward elimination).

Result Regression equation was Logit(P)=—2.349—1.349sex +2.700 age①+1.994 age②+1.291 age③+0.736infectious-disease +0.086 nonce-BMI. (likelihood-ratio-test, X²=4.713 P<0.05).

age① p=0.000 OR=14.876 95% CI: 5.629~39.319

age② p=0.000 OR=7.346 95% CI: 4.222~12.780

age③ p=0.000 OR=3.638 95% CI: 2.056~6.436

sex, p=0.000; OR=0.260; 95% CI: 0.137~0.492

infectious-disease p=0.003 OR=2.087 95% CI: 1.291~3.375

nonce-BMI p=0.011 OR=1.090 95% CI: 1.020~1.165.

Discussion Individual factors interfering with NIHL were age, sex, infectious-disease and nonce-BMI based on analysis. The risk was arranged in order from high to low. Age was highly related to NIHL though hearing threshold had been revised by age and sex, risk was 3.638~14.876 times of reference group. Aging-hearing-loss and NIHL are too similar in audiogram, deafness classification and symptom to distinguish. So did infectious-disease, such as mumps, measles, epidemic-cerebrospinal-meningitis, rubella, chicken-pox and zoster, et al. Nonce-BMI was mildly related to NIHL, risk was 1.090 times. No evidence approved smoking drinking and length-of-service concerned with NIHL, which differed from other researches and should dig further. Good habits are important for occupational health as well as protective measure. It is necessary for employer to do exercising, keep from infectious diseases, maintain reasonable BMI, stop smoking and limit drinking