I am using purple air sensors to measure air quality near the ocean.
By near I meant the sensor is from 50 to 200 feet away from the ocean’s waters edge.
I see higher reading than I expect especially when compared to sensors run by the government that are on the same coast about 20Km away.
There is no nearby source of smoke or pollution that I can identify that would be affecting my readings.
So I wonder will the purple air sensor “see” salt spray in the air from the ocean surf as additional PM2.5?
Could local salt spray in the air affect the reading of PM2.5 from the purple air sensor and result in higher than expected readings?
It is important that I can understand if my reading will be representative of local PM2.5 air quality or simply showing that there is salt spray in the ocean side air.
it looks like it –
but it also looks like fine particulate matter is fine particulate manner, no matter what, so the same sea salt spray that the monitor is picking up is also getting into your body.
I couldn’t find much else in a google search.
edit – found this article too – looks like sea spray is a known contributor to fine particles. Unexpected contributions of sea spray and lake spray aerosol to inland particulate matter (Journal Article) | OSTI.GOV
and it looks like it’s important to measure these particles whether they’re from sea spray, fires, natural or human causes.
I don’t think the sensor can read salt spray as it only reads RH, T, and PM2.5 more info at the EPA webpage.
It is possible. I haven’t looked into that research, but did a quick search and found this:
“Moreover, sea salts accounted for 6.5-11.1% and 11.0-13.5% of PM2.5 at the offshore islands and over sea, respectively”.
I also found this 2012 EPA presentation on PM2.5 composition:
You will be measuring a certain amount of sea salt as this is common in coastal environments.
The Point Reyes IMPROVE site (FED Home) has measured sea salt levels as high as 14 g/m3. This does not include the sea salt sulfate and nitrate components.
The other issue is that these particles are hygroscopic and can absorb water, which can change their diameters and light scattering properties. See Figure 6 of Watson, J.G., (2002). Critical review: Visibility: Science and regulation. Journal of the Air & Waste Management Association, 52, 628-713. http://www.tandfonline.com/doi/pdf/10.1080/10473289.2002.10470813
for an ammonium sulfate example. NaCl follow a similar hygroscopic pattern.
Here are links to a particulate matter study from the SF Bay area. It demonstrates how much the Na and Cl levels measured at sites A and B, which are close to the coastline, are attenuated at Site C, which is quite a bit inland. The closer you are to the coast, the higher the sea salt contribution.
https://www.researchgate.net/publication/235341792_PM_10_concentrations_in_Davenport_CA_between_April_15_1988_and_December_26_1991
Buenas noches, me encuentro en peru y necesitamos adquirir sensores de medición de PM-2.5 para un proyecto de investigación en la Universidad, agradezco la información al respecto