Impacts of urbanization on air quality and the related health risks in a city with complex terrain
<p>Urbanization affects air pollutants via urban expansion and emission growth, thereby inevitably changing the health risks involved with air pollutants. However, the health risks related to urbanization are rarely estimated, especially for cities with complex terrain. In this study, a highly...
| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-01-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/23/771/2023/acp-23-771-2023.pdf |
| Summary: | <p>Urbanization affects air pollutants via urban expansion and
emission growth, thereby inevitably changing the health risks involved with air
pollutants. However, the health risks related to urbanization are rarely
estimated, especially for cities with complex terrain. In this study, a
highly urbanized city with severe air pollution and complex terrain
(Chengdu) is selected to explore this issue. The effects of urban expansion
are further compared with emission growth because air quality management is
usually achieved by regulating anthropogenic emissions. Air pollution in
Chengdu was mainly caused by PM<span class="inline-formula"><sub>2.5</sub></span> and O<span class="inline-formula"><sub>3</sub></span> from 2015 to 2021.
PM<span class="inline-formula"><sub>2.5</sub></span> pollution tended to appear in cold months (November to February)
owing to the blocking of air and the stable atmospheric layer, whereas O<span class="inline-formula"><sub>3</sub></span>
pollution was likely to occur in warm months (April to August) that experience high-temperature and strong-sunlight conditions and are dominated by high-pressure systems.
From 2015 to 2021, the 7-year annual average of premature mortality from
all non-accidental causes (ANACs) due to PM<span class="inline-formula"><sub>2.5</sub></span> and O<span class="inline-formula"><sub>3</sub></span> was 9386
(95 % confidence interval (CI) of 6542–11 726) and 8506 (95 % CI of
4817–11 882), respectively. Based on the characteristics of PM<span class="inline-formula"><sub>2.5</sub></span> and
O<span class="inline-formula"><sub>3</sub></span>, six numerical experiments were conducted to investigate the impacts
of urban expansion and emission growth on the health risks related to air pollutants.
The results show that urban land use led to an increase in the air temperature
and boundary layer height compared with cropland, which was conducive to
the diffusion of PM<span class="inline-formula"><sub>2.5</sub></span>. Thus, the monthly average surface PM<span class="inline-formula"><sub>2.5</sub></span>
concentrations decreased by 10.8 <span class="inline-formula">µ</span>g m<span class="inline-formula"><sup>−3</sup></span> (7.6 %) in January.
However, the monthly average daily maximum 8 h average (MDA8) O<span class="inline-formula"><sub>3</sub></span>
concentrations increased by 10.6 <span class="inline-formula">µ</span>g m<span class="inline-formula"><sup>−3</sup></span> (6.0 %) in July owing
to the stronger photochemical production and better vertical mixing during
daytime. In this case, premature mortality from ANACs due to PM<span class="inline-formula"><sub>2.5</sub></span>
decreased by 171 (95 % CI of 129–200, or about 6.9 %) in January, and
that due to O<span class="inline-formula"><sub>3</sub></span> increased by 203 (95 % CI of 122–268, or about 9.5 %)
in July. As for the effects of emission growth, the monthly average
PM<span class="inline-formula"><sub>2.5</sub></span> and MDA8 O<span class="inline-formula"><sub>3</sub></span> concentrations increased by 23.9 (16.8 %) and 4.8 <span class="inline-formula">µ</span>g m<span class="inline-formula"><sup>−3</sup></span> (2.7 %), respectively, when anthropogenic
emissions were taken into account. Premature mortality from ANACs due to
PM<span class="inline-formula"><sub>2.5</sub></span> and O<span class="inline-formula"><sub>3</sub></span> then increased by 388 (95 % CI of 291–456, or about
15.7 %) and 87 (95 % CI of 54–112, or about 4.1 %), respectively. From a
health risk perspective, the effects of urban land use on the health risks related to
PM<span class="inline-formula"><sub>2.5</sub></span> are about half that of anthropogenic emissions, whereas the
effects of urban land use on the health risks related to O<span class="inline-formula"><sub>3</sub></span> can be 2 times that of
anthropogenic emissions. This emphasizes that, in addition to regulating
anthropogenic emissions, urban planning is also important for urban air
quality, especially for secondary pollutants like O<span class="inline-formula"><sub>3</sub></span>.</p> |
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| ISSN: | 1680-7316 1680-7324 |