The effect of air dust pollution on semen quality and sperm parameters among infertile men in west of Iran

Figures & data

Figure 1. Monthly air pollution data. The panel shows the monthly average concentrations and trends of PM 10 in the ambient air of Kermanshah, Iran, during 2011–2015.

Table 1. Demographic characteristics of the study populations.

Characteristics	n (%)
Age (years)
20–30	219 (25.8)
31–40	463 (54.5)
41–50	150 (17.6)
51–60	13 (1.5)
>60	5 (0.6)
Residential location
Large cities	391 (46)
Small cities	459 (54)
Educational level
High school diploma or lower	625 (73.5)
Bachelor of science or Master of science	214 (25.1)
Doctorate or higher	11 (1.4)
Occupation
Proletarian	101 (11.9)
Solder	101 (11.9)
Clerk	337 (39.7)
Driver	53 (6.2)
Other	460 (54.1)

Data are presented as the number (percentage) for categorical variables.

Table 2. Descriptive statistics for semen parameters before and after laboratory processing of 850 infertile men who presented at Motazedi Infertility Center, 2011–2016.

Sperm parameters	n	Before processing				After processing				Percentage lower than WHO criteria
		Mean (±SD)	25th	50th	75th	Mean (±SD)	25th	50th	75th
Sperm PH value	850	7.53 (±0.07)	7.2	7.5	7.8	7.53 (±0.07)	7.2	7.5	7.8	77.0
Sperm volume (ml)	850	3.26 (±1.87)	2	3	4.5	3.26 (±1.87)	2	3	4.5	92.5
Sperm concentration (10^6/ml)	849	41.77 (±24.45)	25	40	55	36.06 (±22.13)	20	35	50	78.2
Sperm progressive motility (%)	849	21.65 (±10.16)	15	20	30	87.17 (±23.70)	90	98	99	60.7
Sperm morphology (%)	849	5.89 (±2.84)	4	35	8	13.06 (±9.05)	6	10	20	12.4

Abnormal values of semen parameters were defined by the World Health Organization (WHO, 1999 and 2010) standards: pH value <7.2, semen volume <2 ml, sperm concentration <20 × 10⁶/ml, sperm total count <40 × 10⁶ and sperm motility <50%.

Table 3. Summary of semen parameters according to different age groups.

Semen parameters	Age
	20–30	31–40	41–50	51–60	Total	p-Value^a
Sperm concentration before processing (10^6/ml)	(43.72 ± 26.73)	(40.51 ± 22.73)	(43.37 ± 26.07)	(39.84 ± 17.54)	(41.84 ± 24.49)	0.40
Sperm motility before processing (%)	(21.05 ± 11.29)	(22.17 ± 9.17)	(21.40 ± 9.60)	(19.22 ± 17.54)	(21.69 ± 10.17)	0.59
Sperm morphology before processing (%)	(5.70 ± 3.08)	(5.93 ± 2.73)	(6.03 ± 2.77)	(6. 23 ± 3.37)	(5.9 ± 2.84)	0.01
Sperm concentration after processing (10^6/ml)	(35.16 ± 22.13)	(35.95 ± 22.03)	(38.00 ± 22.48)	(37.38 ± 23.28)	(36.13 ± 22.14)	0.40
Sperm motility after processing (%)	(84.05 ± 27.18)	(88.05 ± 21.95)	(88.24 ± 22.95)	(86.38 ± 27.15)	(87.24 ± 23.66)	0.22
Sperm morphology after processing (%)	(12.25 ± 8.76)	(13.04 ± 8.73)	(14.49 ± 10.20)	(12.15 ± 7.83)	(13.08 ± 9.05)	0.87

^a Kruskal–Wallis analysis of variance was used to compare the median between groups.

Table 4. Correlation between semen parameters and PM_0.01–10 levels before and after lab processing.

Semen parameter	PM10 (µg/m^3) Before processing		After processing
	Standardized coefficient β	p-Value	Standardized coefficient β	p-Value
Sperm concentration (10^6 /ml)	−0.105*	0.002	−0.076*	0.023
Sperm motility (%)	−0.054	0.118	−0.020	0.557
Sperm morphology (%)	−0.126**	0.000	−0.146**	0.000

β, The Standardized coefficient Beta.

*Statistically significant at the level 0.05.

**Statistically significant at the level 0.01.

Table 5. Spearman’s Rho, correlation coefficients (R) with 99% confidence intervals between continuous variables in this study.

PM10 (µg/m^3 )			Semen parameters
			Before processing			After processing
			Sperm concentration (10^6 /ml)	Sperm motility (%)	Sperm morphology (%)	Sperm concentration (10^6 /ml)	Sperm motility (%)	Sperm morphology (%)
Spring	April	R	0.032	−0.002	−0.023	0.030	−0.019	−0.009
		p-Value	0.352	0.953	0.501	0.377	0.588	0.799
	May	R	0.068*	0.16	0.010	0.066	−0.003	0.015
		p-Value	0.048	0.636	0.771	0.055	0.921	0.652
	Jun	R	0.056	0.025	0.042	0.092**	0.012	0.010
		p-Value	0.103	0.469	0.220	0.008	0.726	0.762
Summer	July	R	0.055	0.039	0.011	0.064	0.002	0.010
		p-Value	0.090	0.259	0.758	0.065	0.953	0.762
	August	R	−0.934**	−0.641**	−0.539**	−0.793**	−0.322**	−0.4154**
		p-Value	0.000	0.000	0.000	0.000	0.000	0.000
	September	R	0.052	0.025	0.009	0.069*	0.013	0.019
		p-Value	0.129	0.470	0.796	0.045	0.704	0.574
Autumn	October	R	0.001	0.018	−0.106**	−0.039	−0.062	−0.190**
		p-Value	0.980	0. 593	0.002	0.254	0.076	0.000
	Number	R	0.006	−0.017	0.067*	0.008	0.074*	0.130**
		p-Value	0.872	0.623	0.050	0.825	0.030	0.000
	December	R	0.004	0.028	−0.058	−0.009	0.022	0.130**
		p-Value	0.904	0.420	0.089	0.795	0.514	0.000
Winter	January	R	0.058	0.019	0.050	0.065	−0.023	0.034
		p-Value	0.091	0.577	0.148	0.060	0.496	0.324
	February	R	0.001	0.016	−0.107**	−0.037	−0.060	−0.190**
		p-Value	0.973	0.643	0.002	0.282	0.079	0.000
	March	R	0.053	0.020	0.037	0.089**	0.011	−0.190**
		p-Value	0.124	0.556	0.276	0.010	0.743	0.002

R: Correlation coefficients.

*Correlation significant at the 0.05 level (two-tailed).

**Correlation significant at the 0.01 level (two-tailed).