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Short-term effects of air pollution on hospital admissions for cardiovascular diseases and diabetes mellitus in Sofia, Bulgaria (2009–2018) Cover

Short-term effects of air pollution on hospital admissions for cardiovascular diseases and diabetes mellitus in Sofia, Bulgaria (2009–2018)

Archives of Industrial Hygiene and Toxicology
Volume 74 (2023): Issue 1 (March 2023)
By: ,  ,  ,  ,   and    
Open Access
|Apr 2023
Figures & tables

Correction

This article was corrected on Dec 29, 2023

Figures & Tables

Figure 1

Daily hospital admission counts for ischaemic heart disease (IHD), cerebral infarction (CI), and type 2 diabetes mellitus (T2DM) in Sofia, Bulgaria from 2009 to 2018

Figure 2

Daily concentrations of air pollutants in Sofia, Bulgaria from 2009 to 2018. CO – carbon monoxide; NO2 – nitrogen dioxide; O3 – ozone; PM10 – particulate matter ≤10 µm; PM2.5 – particulate matter ≤2.5 µm; SO2 – sulphur dioxide

Table 1

Descriptive statistics for the exposure variables in the study

VariableMissing data
(N, %)		PercentilesMinMax
25th50th75th
PM1045 (1.23)22.3231.2945.383.60601.04
PM2.5204 (5.59)12.2217.7627.100.49485.77
NO223 (0.63)21.4030.0341.700.01184.89
SO225 (0.68)4.626.7210.680.01123.31
O326 (0.71)22.8238.4752.280.3997.27
CO45 (1.23)0.420.610.900.007.83
Temperature20 (0.55)4.7012.4419.19-14.3931.375
Relative humidity20 (0.55)56.2965.8076.2130.5098.26

1 CO – carbon monoxide; NO2 – nitrogen dioxide; O3 – ozone; PM10 – particulate matter ≤10 μm; PM2.5 – particulate matter ≤2.5 μm; SO2 – sulphur dioxide

Table 2

Spearman’s correlations between the key variables in the study

Variables1.2.3.4.5.6.7.8.9.10.11.
1. IHD1.00
2. CI0.52*1.00
3. T2DM0.83*0.50*1.00
4. PM100.05*0.020.021.00
5. PM250.03-0.010.010.88*1.00
6. SO20.07*-0.010.04*0.50*0.55*1.00
7. NO20.15*0.08*0.13*0.77*0.69*0.42*1.00
8. O3-0.15*-0.07*-0.07*-0.48*-0.43*-0.27*-0.62*1.00
9. CO0.09*-0.010.07*0.66*0.69*0.55*0.66*-0.52*1.00
10. Temperature-0.12*-0.02-0.03-0.20*-0.34*-0.53*-0.21*0.49*-0.42*1.000
11. Relative humidity0.09*-0.020.030.08*0.15*0.12*0.07*-0.50*0.30*-0.53*1.00

1 * Correlation is statistically significant at p<0.05. CO – carbon monoxide; CI – cerebral infarction; T2DM – diabetes mellitus; IHD – ischaemic heart disease; NO2 – nitrogen dioxide; O3 – ozone; PM10 – particulate matter ≤10 μm; PM2.5 – particulate matter ≤2.5 μm; SO2 – sulphur dioxide

Table 3

Risk of hospital admissions associated with air pollution levels on the same day (lag0)

PollutantIHD
(IRR)		CI
(IRR)		T2DM
(IRR)
PM100.996 (0.992, 1.000)0.998 (0.995, 1.001)0.995 (0.991, 0.999)*
PM2.50.995 (0.989, 1.001)0.998 (0.994, 1.003)0.993 (0.987, 1.000)
SO20.990 (0.967, 1.013)0.985 (0.960, 1.011)0.991 (0.957, 1.003)
NO21.003 (0.996, 1.010)0.999 (0.993, 1.005)1.002 (0.993, 1.011)
O30.991 (0.982, 1.001)0.995 (0.985, 1.004)0.992 (0.978, 1.006)
CO0.974 (0.948, 1.001)0.982 (0.962, 1.002)0.974 (0.947, 1.003)

1 * Coefficient is statistically significant at p<0.05. All models are adjusted for time trend, day of the week, deciles of temperature, and relative humidity. Coefficients are incidence rate ratios (IRR) with their 95 % confidence intervals scaled per 10 μg/m3 for all other pollutants and per 1 mg/m3 for CO. CO – carbon monoxide; CI – cerebral infarction; IHD – ischemic heart disease; NO2 – nitrogen dioxide; O3 – ozone; PM10 – particulate matter ≤10 μm; PM2.5 – particulate matter ≤2.5 μm; SO2 – sulphur dioxide; T2DM – type 2 diabetes mellitus

Table 4

Risk of hospital admissions associated with above-threshold air pollution levels on the same day (lag0)

PollutantIHD
(IRR)		CI
(IRR)		T2DM
(IRR)
PM10 ≥45 μg/m31.007 (0.980, 1.034)1.000 (0.973, 1.028)0.991 (0.950, 1.034)
PM 5 ≥15 μg/m31.005 (0.982, 1.029)1.004 (0.979, 1.030)0.997 (0.959, 1.036)
SO ≥40 μg/m30.952 (0.858, 1.056)0.915 (0.796, 1.053)1.003 (0.827, 1.216)
NO ≥25 μg/m31.039 (1.013, 1.066)*1.019 (0.993, 1.045)1.029 (0.991, 1.069)
O ≥60 μg/m30.971 (0.935, 1.008)0.976 (0.941, 1.012)0.944 (0.893, 0.997)*
CO ≥4 mg/m30.929 (0.810, 1.064)0.995 (0.912, 1.085)0.875 (0.771, 0.994)*

1 * Coefficient is statistically significant at p<0.05. All models are adjusted for time trend, day of the week, deciles of temperature, and relative humidity. Coefficients are incidence rate ratios (IRR) with their 95 % confidence intervals. CO – carbon monoxide; CI – cerebral infarction; IHD – ischemic heart disease; NO2 – nitrogen dioxide; O3 – ozone; PM10 – particulate matter ≤10 μm; PM2.5 – particulate matter ≤2.5 μm; SO2 – sulphur dioxide; T2DM – type 2 diabetes mellitus

Table 5

Risk of hospital admissions associated with deciles of air pollutant levels on the same day (lag0)

DecilesPM10PM2.5SO2NO2O3CO
Ischaemic heart disease (IRR)
D20.993 (0.948, 1.041)1.007 (0.959, 1.058)1.005 (0.959, 1.054)1.019 (0.970, 1.070)1.022 (0.975, 1.072)0.996 (0.953, 1.041)
D30.976 (0.934, 1.019)1.021 (0.977, 1.067)1.001 (0.952, 1.053)0.995 (0.945, 1.048)1.057 (1.004, 1.114)*0.997 (0.949, 1.047)
D40.976 (0.933, 1.022)0.989 (0.945, 1.036)1.014 (0.962, 1.068)1.031 (0.980, 1.086)1.022 (0.968, 1.078)0.981 (0.929, 1.035)
D50.953 (0.908, 1.000)1.004 (0.959, 1.050)1.012 (0.962, 1.065)1.027 (0.977, 1.080)1.02 (0.965, 1.078)0.998 (0.944, 1.054)
D61.004 (0.958, 1.053)1.015 (0.966, 1.067)0.990 (0.937, 1.045)1.046 (0.994, 1.100)1.033 (0.977, 1.092)1.009 (0.954, 1.067)
D70.983 (0.941, 1.027)1.000 (0.954, 1.048)1.011 (0.957, 1.069)1.078 (1.025,1.134)*0.978 (0.923, 1.037)1.012 (0.960, 1.067)
D81.008 (0.965, 1.053)0.998 (0.956, 1.042)0.997 (0.943, 1.053)1.055 (1.003,1.109)*0.982 (0.924, 1.043)1.007 (0.951, 1.067)
D91.022 (0.977, 1.070)1.011 (0.965, 1.060)0.999 (0.940, 1.061)1.067 (1.012,1.125)*0.981 (0.921, 1.045)1.048 (0.994, 1.106)
D100.944 (0.895, 0.997)*1.006 (0.953, 1.062)0.962 (0.895, 1.035)1.039 (0.983, 1.098)0.960 (0.897, 1.027)0.981 (0.922, 1.044)
Cerebral infarction (IRR)
D20.973 (0.929, 1.020)1.023 (0.977, 1.072)0.968 (0.915, 1.024)1.032 (0.981, 1.086)1.027 (0.980, 1.076)0.957 (0.913, 1.003)
D31.016 (0.967, 1.068)0.992 (0.945, 1.042)0.977 (0.924, 1.033)1.033 (0.984, 1.085)1.035 (0.984, 1.089)0.957 (0.908, 1.009)
D40.988 (0.939, 1.040)1.034 (0.984, 1.087)0.942 (0.889, 0.998)*1.042 (0.991, 1.097)1.058 (1.005,1.114)*0.965 (0.913, 1.020)
D51.004 (0.954, 1.057)1.038 (0.987, 1.092)0.971 (0.915, 1.030)1.060 (1.008,1.115)*1.023 (0.970, 1.079)0.957 (0.905, 1.011)
D60.975 (0.927, 1.027)1.018 (0.966, 1.073)0.960 (0.903, 1.020)1.038 (0.988, 1.090)0.986 (0.931, 1.045)0.976 (0.922, 1.034)
D70.994 (0.943, 1.046)1.022 (0.967, 1.080)0.973 (0.914, 1.036)1.053 (1.001,1.107)*1.010 (0.952, 1.073)0.995 (0.936, 1.057)
D81.004 (0.953, 1.058)1.023 (0.971, 1.079)0.982 (0.921, 1.047)1.050 (0.995, 1.108)1.011 (0.950, 1.075)0.963 (0.905, 1.024)
D90.983 (0.931, 1.038)0.981 (0.926, 1.039)0.975 (0.913, 1.040)1.072 (1.018,1.128)*0.987 (0.927, 1.052)0.961 (0.903, 1.023)
D100.965 (0.913, 1.020)1.000 (0.942, 1.060)0.936 (0.869, 1.009)0.997 (0.946, 1.052)0.995 (0.929, 1.067)0.929 (0.872, 0.989)*
Type 2 diabetes mellitus (IRR)
D20.986 (0.918, 1.058)1.019 (0.949, 1.095)0.968 (0.889, 1.055)1.050 (0.971, 1.135)0.992 (0.924, 1.065)0.986 (0.914, 1.063)
D30.933 (0.868, 1.002)0.984 (0.914, 1.059)0.958 (0.876, 1.048)1.009 (0.934, 1.090)1.010 (0.938, 1.087)0.999 (0.921, 1.083)
D40.930 (0.865, 1.000)0.951 (0.883, 1.025)0.991 (0.905, 1.086)1.003 (0.928, 1.085)0.985 (0.913, 1.063)0.947 (0.870, 1.031)
D50.925 (0.858, 0.997)*0.988 (0.916, 1.065)0.971 (0.887, 1.063)1.058 (0.979, 1.144)0.965 (0.890, 1.045)0.944 (0.865, 1.030)
D60.987 (0.916, 1.063)0.988 (0.916, 1.066)0.941 (0.858, 1.033)1.006 (0.930, 1.087)0.985 (0.907, 1.071)0.959 (0.877, 1.048)
D70.952 (0.884, 1.025)0.978 (0.905, 1.056)0.977 (0.888, 1.074)1.094 (1.012,1.182)*0.990 (0.907, 1.080)0.960 (0.877, 1.051)
D80.961 (0.891, 1.036)0.999 (0.924, 1.080)0.956 (0.867, 1.053)1.023 (0.944, 1.108)0.997 (0.910, 1.092)0.977 (0.890, 1.071)
D90.963 (0.891, 1.041)0.986 (0.909, 1.068)1.010 (0.914, 1.116)1.042 (0.961, 1.130)0.982 (0.893, 1.080)0.985 (0.898, 1.081)
D100.941 (0.868, 1.020)0.975 (0.895, 1.063)0.919 (0.823, 1.026)1.059 (0.974, 1.151)0.926 (0.837, 1.025)0.971 (0.882, 1.068)

1 * Coefficient is statistically significant at p<0.05. D2–10 stand for deciles, where D1 is the reference category (not shown). All models are adjusted for time trend, day of the week, deciles of temperature, and relative humidity. Coefficients are incidence rate ratios (IRR) with their 95 % confidence intervals. CO – carbon monoxide; NO2 – nitrogen dioxide; O3 – ozone; PM10 – particulate matter ≤10 μm; PM2.5 – particulate matter ≥2.5 μm; SO2 – sulphur dioxide

Figure 3

Risk of hospital admissions for ischaemic heart disease associated with air pollution levels over seven days. Lag models for the effects of pollutant concentrations include mutually adjusted 0–7 day lags, averaged over 3 and 7 days (lags 0–3 and 0–7), and the cumulative effect of lags 0–7 (net sum of lagged effects). All models are adjusted for time trend, day of the week, deciles of temperature, and relative humidity. Pollutants are tested one-at-a-time (single-pollutant models). Coefficients shown are incidence rate ratios (IRR) with 95 % confidence intervals, where intervals not crossing the horizontal reference line indicate statistically significant estimates. CO – carbon monoxide; NO2 – nitrogen dioxide; O3 – ozone; PM10 – particulate matter ≤10 µm; PM2.5 – particulate matter ≤2.5 µm; SO2 – sulphur dioxide

Figure 4

Risk of hospital admissions for cerebral infarction associated with air pollution levels over seven days. Lag models for the effects of pollutant concentrations include mutually adjusted 0–7 day lags, averaged over 3 and 7 days (lags 0–3 and 0–7), and the cumulative effect of lags 0–7 (net sum of lagged effects). All models are adjusted for time trend, day of the week, deciles of temperature, and relative humidity. Pollutants are tested one-at-a-time (single-pollutant models). Coefficients shown are incidence rate ratios (IRR) with 95 % confidence intervals, where intervals not crossing the horizontal reference line indicate statistically significant estimates. CO – carbon monoxide; NO2 – nitrogen dioxide; O3 – ozone; PM10 – particulate matter ≤10 µm; PM2.5 – particulate matter ≤2.5 µm; SO2 – sulphur dioxide

Figure 5

Risk of hospital admissions for type 2 diabetes mellitus associated with air pollution levels over seven days. Lag models for the effects of pollutant concentrations include mutually adjusted 0–7 day lags, averaged over 3 and 7 days (lags 0–3 and 0–7), and the cumulative effect of lags 0–7 (net sum of lagged effects). All models are adjusted for time trend, day of the week, deciles of temperature, and relative humidity. Pollutants are tested one-at-a-time (single-pollutant models). Coefficients shown are incidence rate ratios (IRR) with 95 % confidence inter vals, where intervals not crossing the horizontal reference line indicate statistically significant estimates. CO – carbon monoxide; NO2 – nitrogen dioxide; O3 – ozone; PM10 – particulate matter ≤10 µm; PM2.5 – particulate matter ≤2.5 µm; SO2 – sulphur dioxide

Figure 6

Risk of hospital admissions for ischemic heart disease associated with air pollution levels over seven days stratified by gender and age. Legend: circles – male <65 yrs.; squares – female <65 yrs.; triangles – male ≥65 yrs.; diamonds – female ≥65 yrs. Lag models for the effects of pollutant concentrations include mutually adjusted 0–7 day lags, averaged over 3 and 7 days (lags 0–3 and 0–7), and the cumulative effect of lags 0–7 (net sum of lagged effects). All models are adjusted for time trend, day of the week, deciles of temperature, and relative humidity. Pollutants are tested one-at-a-time (single-pollutant models). Coefficients shown are incidence rate ratios (IRR) with 95 % confidence inter vals, where intervals not crossing the horizontal reference line indicate statistically significant estimates. CO – carbon monoxide; NO2 – nitrogen dioxide; O3 – ozone; PM10 – particulate matter ≤10 µm; PM2.5 – particulate matter ≤2.5 µm; SO2 – sulphur dioxide

Table 6

Risk of hospital admissions associated with air pollution on the same day (lag0), stratified by time of year

PollutantApril — SeptemberOctober — March
IHD
(IRR)		Cl
(IRR)		T2DM
(IRR)		IHD
(IRR)		Cl
(IRR)		T2DM
(IRR)
PM101.020 (1.000, 1.041)*1.004 (0.984, 1.024)0.999 (0.970, 1.029)0.995 (0.991, 0.999)*0.997 (0.995, 1.000)0.994 (0.990, 0.997)*
PM2.51.010 (0.983, 1.038)1.011 (0.981, 1.041)1.026 (0.980, 1.073)0.992 (0.986, 0.999)*0.997 (0.993, 1.001)0.993 (0.987, 0.999)*
SO20.979 (0.909, 1.055)1.056 (0.990, 1.126)1.001 (0.903, 1.111)0.988 (0.969, 1.008)0.982 (0.960, 1.004)0.964 (0.934, 0.996)*
NO21.038 (1.018,1.057)*1.022 (1.006,1.041)*1.026 (1.000,1.052)*0.996 (0.988, 1.003)0.996 (0.990, 1.003)0.997 (0.988, 1.006)
O30.984 (0.970, 0.997)*0.994 (0.982, 1.007)0.987 (0.968, 1.007)0.995 (0.983, 1.006)1.003 (0.991, 1.015)0.993 (0.976, 1.011)
CO1.071 (0.978, 1.175)0.978 (0.887, 1.078)1.010 (0.874, 1.169)0.964 (0.937, 0.992)*0.978 (0.961, 0.996)*0.969 (0.943, 0.996)*

1 * Coefficient is statistically significant at p<0.05. All models are adjusted for time trend, day of the week, deciles of temperature, and relative humidity. Coefficients are incidence rate ratios (ERR) with their 95 % confidence intentais scaled per 10 μg/m3 for all other pollutants and per 1 mg/m3 for CO. CO – carbon monoxide; Cl – cerebral infarction; IHD – ischemic heart disease; NO2 – nitrogen dioxide; O3 – ozone; PM10 – particulate matter ≤10 μm; PM2.5 – particulate matter ≤2.5 μm; SO2 – sulphur dioxide; T2DM – type 2 diabetes mellitus

Figure 7

Risk of hospital admissions for cerebral infarction associated with air pollution levels over seven days stratified by gender and age. Legend: circles – male <65 yrs.; squares – female <65 yrs.; triangles – male ≥65 yrs.; diamonds – female ≥65 yrs.

Lag models for the effects of pollutant concentrations include mutually adjusted 0–7 day lags, averaged over 3 and 7 days (lags 0–3 and 0–7), and the cumulative effect of lags 0–7 (net sum of lagged effects). All models are adjusted for time trend, day of the week, deciles of temperature, and relative humidity. Pollutants are tested one-at-a-time (single-pollutant models). Coefficients shown are incidence rate ratios (IRR) with 95 % confidence inter vals, where intervals not crossing the horizontal reference line indicate statistically significant estimates. CO – carbon monoxide; NO2 – nitrogen dioxide; O3 – ozone; PM10 – particulate matter ≤10 µm; PM2.5 – particulate matter ≤2.5 µm; SO2 – sulphur dioxide

Figure 8

Risk of hospital admissions for type 2 diabetes mellitus associated with air pollution levels over seven days stratified by gender and age. Legend: circles – male <65 yrs.; squares – female <65 yrs.; triangles – male ≥65 yrs.; diamonds – female ≥65 yrs. Lag models for the effects of pollutant concentrations include mutually adjusted 0–7 day lags, averaged over 3 and 7 days (lags 0–3 and 0–7), and the cumulative effect of lags 0–7 (net sum of lagged effects). All models are adjusted for time trend, day of the week, deciles of temperature, and relative humidity. Pollutants are tested one-at-a-time (single-pollutant models). Coefficients shown are incidence rate ratios (IRR) with 95 % confidence inter vals, where intervals not crossing the horizontal reference line indicate statistically significant estimates. CO – carbon monoxide; NO2 – nitrogen dioxide; O3 – ozone; PM10 – particulate matter ≤10 µm; PM2.5 – particulate matter ≤2.5 µm; SO2 – sulphur dioxide

DOI: https://doi.org/10.2478/aiht-2023-74-3704 | Journal eISSN: 1848-6312 (formerly 0004-1254) | Journal ISSN: 0004-1254
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Language: English, Croatian
Page range: 48 - 60
Submitted on: Jan 1, 2023
Accepted on: Mar 1, 2023
Published on: Apr 4, 2023
Published by: Institute for Medical Research and Occupational Health
In partnership with: Paradigm Publishing Services
Keywords:
exacerbation,
ischaemic heart diseases,
particulate matter,
stroke,
time series,
type 2 diabetes mellitus
Related subjects:
Medicine,
Basic medical science,
Basic medical science, other

© 2023 Angel M. Dzhambov, Krasimira Dikova, Tzveta Georgieva, Teodor I. Panev, Plamen Mukhtarov, Reneta Dimitrova, published by Institute for Medical Research and Occupational Health
This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License.

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