Respiratory Effects of Particulate Matter Exposure During Short-Term Cycling Among Healthy Adults in Three Chinese Cities

DOI: https://doi.org/10.21203/rs.3.rs-134774/v1

Abstract

Background: Cycling to work has been promoted as a green commute in many countries because of its reduced congestion relative to that of cars and its reduced environmental impact on air pollution. However, cyclists might be exposed to higher air pollution, causing adverse health effects. Few studies have examined the respiratory effects of traffic-related air pollution exposure during short-term cycling, especially in developing countries with heavy air pollution. The aim of this study was to assess the impact of air pollution exposure on lung function while cycling in traffic.

Methods: Twenty-five healthy adults in total cycled on a specified route in each of three Chinese cities during four periods of a day. Lung function measures were collected immediately before and after cycling. Real-time particulate matter (PM) and the particle number count (PNC) for particles with different sizes were measured along each cycling route, while ambient sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3), and carbon monoxide (CO) levels were measured at the nearest stations. Mixed-effect models were used to estimate the impact of short-term air pollution exposure on participants’ lung function measures during cycling.

Results: We found that an interquartile increase in particulate matter consisting of fine particles (PM1, aerodynamic diameter £ 1 mm; and PM2.5, aerodynamic diameter £ 2.5 mm) was associated with a significant decrease in forced vital capacity (FVC) (PM1, –5.61%, p = 0.021; PM2.5, –5.57%, p = 0.022). Interquartile increases in the 99th percentile of PNC for fine particles (aerodynamic diameter 0.3–0.4 mm) also had significant negative associations with FVC (0.3 mm, –5.13%, p = 0.041; 0.35 mm, –4.81%, p = 0.045; 0.4 mm, –4.59%, p = 0.035). We also observed significant inverse relationships between ambient CO levels and FVC (–5.78%, p = 0.015).

Conclusions: Our results suggest that short-term exposure to fine particles and CO while cycling in traffic contributes to a reduction in FVC of cyclists. 

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Tables

Table 1 Descriptive characteristics of participants

Characteristics

Sex: Number (%)

 

  Male

13 (52%)

  Female

12 (48%)

Age: Mean (Range)

24.72 (19–38)

Height (m): Mean (Range)

1.671 (1.54–1.83)

BMI (kg/m2): Mean (Range)

21.24 (17.29–33.20)

Trip duration (min): Mean (Range)

18.26 (10.4–28.3)

Smoker

0 (0%)

Asthma

0 (0%)

With allergies

3 (12%)

 

Table 2 Comparison of lung function measurements immediately before and after cycling

 

 

N

Pre-trip

Post-trip

Change

p-value

FVC (L)

Pooled

120

3.62 (1.10)

3.46 (1.13)

-0.16 (0.67)

< 0.001

Guangzhou

40

3.46 (0.91)

3.34 (0.75)

-0.12 (0.54)

0.088

Shanghai

40

4.01 (0.72)

4.02 (1.17)

0.02 (0.89)

0.878

Xi’An

40

3.40 (1.45)

3.03 (1.21)

-0.37 (0.46)

< 0.001

FEV1 (L)

Pooled

120

3.33 (1.04)

3.07 (0.98)

-0.27 (0.76)

< 0.001

Guangzhou

40

3.39 (0.80)

3.27 (0.67)

-0.12 (0.52)

0.059

Shanghai

40

3.31 (0.85)

2.96 (1.01)

-0.35 (1.14)

0.021

Xi’An

40

3.30 (1.39)

2.97 (1.18)

-0.33 (0.43)

< 0.001

FEV1%

Pooled

120

0.92 (0.15)

0.90 (0.19)

-0.02 (0.16)

0.353

Guangzhou

40

0.99 (0.04)

0.99 (0.05)

0.00 (0.02)

0.921

Shanghai

40

0.83 (0.18)

0.75 (0.22)

-0.08 (0.27)

0.029

Xi’An

40

0.95 (0.16)

0.96 (0.16)

0.01 (0.07)

0.245

PEF (L/s)

Pooled

120

10.18 (4.21)

9.83 (4.11)

-0.35 (1.50)

0.054

Guangzhou

40

10.89 (2.68)

10.84 (2.82)

-0.05 (1.16)

0.825

Shanghai

40

10.35 (4.38)

9.84 (4.75)

-0.50 (1.62)

0.121

Xi’An

40

9.30 (5.15)

8.80 (4.48)

-0.49 (1.67)

0.090

FEF25–75% (L/s)

Pooled

120

4.86 (1.91)

4.79 (1.95)

-0.07 (0.83)

0.343

Guangzhou

40

5.08 (1.30)

5.05 (1.29)

-0.02 (0.79)

0.907

Shanghai

40

4.88 (1.71)

4.70 (2.18)

-0.18 (0.66)

0.114

Xi’An

40

4.63 (2.30)

4.61 (2.19)

-0.02 (1.01)

0.952