The smallest air pollution particles block the most sunlight, scientists find

Air pollution blocks more sunlight from reaching the Earth’s surface the smaller the particles are, scientists in China have found.

The scientists looked to find out how air pollution affects surface solar radiation (SSR) — the energy the sun delivers to the Earth’s surface via sunlight — under cloud-free skies in Nanjing, China.

The findings, published in the journal Advances in Atmospheric Sciences, warned that air pollution could negatively affect renewable energy harvests, leaving countries facing an economic burden.

Unlike previous studies, which looked at how air pollution affects sunlight in different seasons or years, this study focused on air pollution’s effects on sunlight in the absence of other obstructions like clouds or rain.

‘To the best of our knowledge, few studies have analysed the effects of different levels of air pollution on SSR under clear skies,’ said Dr. Yong Han, professor at the School of Atmospheric Sciences at Sun Yat-Sen University in Guangzhou, China.

Nanjing, China.

The amount of sunlight that reaches the Earth’s surface often fluctuates as it is scattered by cloud cover, but it can also be dispersed by particulate aerosols like dust and ash.

Using observations and numerical simulations, the researchers found that SSR is more prone to scattering as air pollution increases, meaning that less sunlight reaches the Earth’s surface.

This effect is particularly associated with increased amounts of fine particulate matter (PM2.5), while coarse particles (PM10) have little effect.

The scientists have warned that the findings mean that air pollution could potentially reduce the amount of energy gained from solar panels.

This could have knock-on effects on future efforts to obtain renewable energy from solar power, both in China and across the world.

The scientists will now look to analyse air quality data from different cities under clear and cloudy skies to explore the relationship between air pollution, clouds and radiation.

‘Our ultimate goal is to understand processes related to aerosol, cloud and radiation, and develop measurable parameters to improve climate and weather prediction models,’ said Dr. Chunsong Lu, co-author of the study and professor at Nanjing University of Information Science and Technology’s Key Laboratory.

China is already the world’s largest producer of photovoltaic (PV) power, the power generated from solar panels.

However, this study adds to concerns that ‘global dimming’ caused by aerosols and soot could limit China’s PV potential if left unchecked.

Researchers believe that China’s poor air quality could cost the country between $4.6bn and $6.7bn by 2030 unless urgent action is taken on air pollution.

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