Monday, April 20, 2020

Can flying ever go green?

Define green.

Today I learned that United Airlines uses biofuels from municipal sewage for a portion of their jet fuel for flights out of LAX.  In 2016, they contracted to purchase up to 15 Million gallons of biofuel over 3 years.  At the end of the contract, they signed up to purchase up to 10 M gal/year, doubling their use.

In 2016, WaPost wrote that the biofuel would be blended in a mixture of 30 percent biofuel and 70 percent traditional fuel.
But the use of biofuels is one possibility for existing machines to cut down on their emissions without having to upgrade their engines or other aspects of their design or engineering. “Drop-in” fuels are renewable fuels that are designed to work safely with existing engines, although as in the case of the United flights, they sometimes require mixing with traditional fuels.
This is analogous to cars in California using a blend of 15% bioethanol and 85% gasoline. If the ethanol comes from grains like corn, then the carbon savings is minimal.  If the bioethanol and biomethane comes from food waste, then the payoff is bigger.

Putting it in perspective.  United Airlines used 4292 Million gallons of fuel in 2019, of which 5 M gal was biofuel.  Even if they were to double that to 10 M gal/year, that would be 0.2% of their fuel use.

So, biofuels in airplanes is better than diesel.  But it's even better if we cut down on our flying overall.  It doesn't have to be much.  Cut down on one round trip long haul flight per year and it's as much carbon savings as if you traded in your gasoline-powered car for an electric car.

I copied the figure from Quantifying the potential for climate change mitigation of consumption options, which I also wrote about in New Paper on Global Data-Driven Climate Actions.

We cut back on personal flights so that we make one long-haul trip every few years.  I was supposed to fly home from Germany yesterday-today.  Bad Dad was going to represent his family at the commemoration of the liberation of Bergen Belsen 75 years ago.  The ceremony will be postponed.

We don't fly long distances for short trips.  We make fewer, longer trips.  We had planned to spend 3 weeks, visiting Berlin, Munich and some smaller towns in between.  I even planned to show him the small town where I had been an exchange student in high school (German Gymnasium.)  It will have to wait.

Friday, April 17, 2020

Poor planning and governance, not density, is the problem

I want to push back against the idea that density and transit necessarily have to spread COVID-19. Dense NYC may be the site of a particularly bad outbreak, but much denser Asian and European cities did much better despite high transit use. The difference is in better institutional planning and personal actions for disease containment.

Density is not the problem. It's the type of density. If you ban Asian metropolis-style apartment buildings, you get low-paid workers crammed 4 to a bedroom in a single-family home in Elmhurst, Queens, NYC. Or 23 people in a house in northeast Los Angeles.

In the words of Richard Florida
But even in the U.S., it is not density in and of itself that seems to make cities susceptible, but the kind of density and the way it impacts daily work and living. That’s because places can be dense and still provide places for people to isolate and be socially distant. Simply put, there is a huge difference between rich dense places, where people can shelter in place, work remotely, and have all of their food and other needs delivered to them, and poor dense places, which push people out onto the streets, into stores and onto crowded transit with one another.

Thursday, April 16, 2020

New Paper on Global Data-Driven Climate Actions

Local experience is not always generalizable. But, you sum up research on a bunch of places, and then patterns emerge. In Data-Driven Climate Action (for Los Angeles) I said:
In summary, decarbonizing transportation has the highest potential for stopping Climate Change, but it requires collective action. We can’t choose to bike along a street that doesn’t create a safe space for us or take a bus to an evening concert if the buses don’t operate at night. An urban area is precisely where these two modes can excel, if we let them. We don’t need a solution that works in Iowa or New Hampshire or even Fresno. We have the existing density and the weather to do this right here, right now. Let’s paint those streets Green (bike lane) & Red (bus lane).
A recent meta-analysis by Diana Ivanova, John Barrett, Dominik Wiedenhofer, Biljana Macura, Max W Callaghan and Felix Creutzig, examined
6,990 records in the Web of Science Core Collections and Scopus. Searches were restricted to 1) reviews of lifecycle assessment studies and 2) multiregional input-output studies of household consumption, published after 2011 in English. We selected against pre-determined eligibility criteria and quantitatively synthesized findings from 53 studies in a meta-review. We identified 771 original options, which we summarized and presented in 61 consumption options with a positive mitigation potential.
They really did their homework on a global scale.  Climate mitigation measures were broadly separated into transportation, food, housing and other.  The combined findings are plotted together on a single box and whiskers chart.
The findings for each study are plotted with circles.  The extreme values are marked with "whiskers" at the end of the bars showing the full range of values. The 25th and 75th percentiles bound the "box". The average value is marked with a large X. The median is marked with a vertical line. 

For context, we need to reduce global CO2 productions by 55% to limit climate change to a global average of 1.5℃ (We've already warmed up 0.8℃ and 1.0℃ is already baked in due to past emissions alone.)  That means each person on earth can contribute 2.1 tCO2eq/cap (metric tons of CO2 or equivalent of emissions  per capita per year.) Americans and Australians contribute 16.7 and 16.2 tCO2eq/cap of emissions.

Note that some of the mitigation strategies can cause negative reductions or increases in CO2 emissions. The authors call that rebound--when the cure is worse than the disease.

The biggest difference that we can make, with the least cost and risk, is to live car-free. I get a lot of eye-rolling, mainly from older people in the US, when I mention this. We are apparently so exceptional in the US that physics and logic could simply not apply to us.

We know how this worked out for COVID-19. Ignore scientists and the results are apparent in a few weeks.

We have been telling you to get out of your car to save the planet for decades, and the result is so slow-moving, that we've been ignored or told we are crazy.

Physics and viruses don't care. They do what they are going to do.

Here's a closer look at just the transportation sector. See the range of values for "Live car-free?" The extreme high value is for ditching an SUV, which also happens to be the most popular car style in America. Losing the family SUV is a huge savings of about 3.6 metric tons of CO2 per capita per year.

I can already hear the, "Yes, but" crowd pointing to the Battery Electric Vehicles (BEV).  Don't they offer almost as much CO2 reduction?

The answer is maybe.  Notice that a significant chunk of the data points for BEV fall in the pink, rebound area, where they cause a net INCREASE in CO2 emissions.  E.g. the BEV is charged with fossil fuel-generated electricity or other externalities that cause other emissions to go up.  Los Angeles falls in the pink area for the reasons I explained in Data-Driven Climate Action (for Los Angeles).

Notice Fuel Cell Vehicles (FCVs) at the bottom?  Hydrogen fuel cells get a lot of hype, but don't save CO2 emissions and they run a huge rebound risk.

I've been accused of confirmation bias because I keep pointing to cars as the culprit for so many ills.  Look at the data.  The biggest bang for the buck is to reduce the distances that you travel, and then travel in the most environmentally-light way.  Walk, bike,  eBike, eScooter, transit, carpool, drive a fuel-efficient car (small and/or hybrid, or BEV.)

Our family made the calculation that, a BEV would be a fine SECOND car, but not our ONLY car.  We drive to SF visit family and have seen the waits to use the fast chargers on Interstate 5.  We also like to take family car trips to remote places with no BEV chargers.

I have seen the South Bay CCOG statistics of car ownership.  I've seen the Vehicle Miles Traveled (VMT) data for Los Angeles county.  In the relatively affluent South Bay, there is about one car per licensed driver.  We have 1 car for 3 drivers. We've essentially taken 2 cars off the road compared to our neighbors.

By having only one car, and making it a fuel-efficient hybrid, our entire family has had to learn how go about our daily routines without a car.  This leads to non-linear savings.  If you always have a car available to you, you use it.  If you can't count on having a car available, then you learn to make most of your trips without a car.

Learning to live "car-light" saves us money, reduces air & water pollution, mitigates climate change, reduces competition for parking spaces in our neighborhood and forces us to get more exercise.  Those are all very positive outcomes and does not require us to wait for a build-out of BEV charging infrastructure.

Ivanova et al strikes an optimistic note.  If you just do the top 10 changes, we make substantial global progress.
The top consumption options (by medians) include substantial changes in car travel (living car-free, shifting to electric vehicles and public transport), air travel reductions, use of renewable electricity and more sustainable heating (renewable-based heating and heat pump), refurbishment and renovation, a shift to a plant-based diet and improved cooking equipment. The top 10 consumption options together (accounting for the overlap of car travel alternatives) yield an average annual mitigation potential of 9.2 tCO2eq/cap. While crudely estimated, this indicates a substantial mitigation potential of already available low-carbon consumption options towards achieving the 1.5-2°C target.
Make the changes that you can, given the society that we live in. Then organize to create a society where more of us can make choices that are better for the planet. We collectively built the auto-centric landscape in the past 70 years. We can collectively rebuild it.

Wednesday, April 15, 2020

Los Angeles County Water Quality: Good News

Finally, some good news. Well, this report is nearly 2 months old, but I think we need some good news right now.

As I mentioned before, I am the Natural Resources chair for the League of Women Voters of Los Angeles County. I write a monthly roundup about environmental issues for LWV voters and opportunities for action. The LWV LA County board meets on the first week of each month, so I wrote this roundup at the end of February/beginning of March. If you want to get on the dissemination list for the monthly reports, leave a comment with your email address. This is just the part that pertains to water.

Executive Summary
LA county drinking water supply is exceptionally safe compared to the rest of the country and state, but arsenic and coliform bacteria contamination of rural drinking water supplies on the northern edge of the county is a concern. Water affordability is a major problem everywhere but Sacramento is working on it. We should prepare for another drought year.
Longer Story

The UCLA Luskin Center for Innovation published a major water report:
Community Water Systems in Los Angeles County: A Performance Policy Guide

LA County drinking water supply is generally very safe and much safer than other parts of the country and CA. Primary Health Maximum Contamination Load (MCL) violations are exceptionally low and concentrated in rural sites along the northern border of LA county.

[In general, rural water systems struggle the most under the burdens of agricultural and mining contamination, naturally occurring arsenic and selenium, and the cost of running longer pipes between low-density housing developments.]

See the green line bouncing near zero at the bottom, that's LA County.  With 10 Million people, we have a pretty big denominator.

The Antelope Valley Times breaks it down further. Only 5 water systems, with about 1,600 total customers, were unable to meet safety standards for levels of naturally-occurring arsenic.  (All water systems met the other safety criteria.)  "Each of them has agreed to provide alternate drinking water to customers until the systems are able to serve water that meets standards."

All 5 systems rely on wells and are near the northern edge of LA county and 4 of the 5 are mobile home parks.  Assuming an average household size of 3, that's less than 5,000 out of 10 million people whose tap water is unsafe.

That's still too many, but the number has been going down as smaller, poorer water systems are merged into larger and wealthier ones.  Thus, the cost of securing and distributing clean water can be shared between more customers.

John Fleck's book, Water is for Fighting Over and Other Myths about Water in the West, has a chapter of how Los Angeles county cities cooperated and managed groundwater for the common good (starting in the 1940s!) The rest of the state is struggling (unsuccessfully) with their own Groundwater Management Plans 80 years later.

When I went to meetings with pro-environmental groups, I've heard people decry water contamination and bandy about talking points that are not supported by evidence.  One woman exclaimed that jet fuel and other chemicals have been found in groundwater everywhere.  I tried to rebut that, but no one in the room wanted to hear it.  So I'm going to vent now.
  • There are a few places where groundwater is contaminated, but they have mostly been cleaned up or are in the process of being cleaned up or contained.
  • Well water is regularly tested in LA County.  If it is contaminated, the well is no longer used and the source of the contamination is investigated and cleaned up.
  • If the groundwater beneath your area is contaminated, your tap water is imported from other areas with cleaner and safe water (except for the 1600 households mentioned above)
  • Tap water is regularly tested and the results are sent to each household in your water bills.
  • The main problem with our local water supply is the hardness (Total Dissolved Solids aka TDS).  I use a Brita filter to remove some of the TDS and chlorine smell for the water I drink. 
  • My landscaping plants prefer soft rainwater over hard tap water.  We try to harvest runoff from rooftops and the driveway and direct that into the landscaping. This reduces salt build up in the soil and the amount of irrigation water that we use.  Win-win!

So why are so many people buying bottled water?

Truck drivers are risking their lives to keep our stores stocked with necessitiesGrocery workers are dying of coronavirus.  Do not put them at risk to haul, stock and sell stuff that you don't need, like bottled water.  Drink tap water.

Use a filter (if you have it) or just fill containers with tap water after you do the dishes and let the water sit over night.  The chlorine taste will dissipate and the water will taste fine.

In the words of Prime Minister of Sint Maarten, Silveria E Jacobs, the water is not going to stop.

Her full address is posted on YouTube. She comes on around minute 23. The famous clip starts at minute 60:

This is not a hurricane. The water is not going to stop. Don't rush to buy water. Buy enough food and toilet paper to last for one to two weeks.

"If you do not have the type of bread you like in your house, eat crackers. If you do not have bread, eat cereal. Eat oats."

Similarly, Coronavirus is not an earthquake. Yes, you should have a few gallons of water per person in your earthquake kit. But you do not need to purchase more bottled water right now. Drink tap water and you may save the life of an essential worker.

Off soapbox. Now go wash your hands.

Friday, April 10, 2020

Coronavirus and water: what we know and don't know

Bad Dad and I met in a chemistry lab and most of our friends are also in STEM.  I just want to clear up some points of confusion about Coronaviruses (CV) for the lay public.

First off, don't panic if you are among the many that can't find cleaning supplies.  We're running low on TP and cleaning supplies at our house but we still have soap.  Fortunately, you don't need anything fancy and you probably have enough around your house.

Coronaviruses (CV) have a lipid (fatty) envelope and detergents break up their envelope/shell.  Without it, the RNA inside can't force their way into your cells.  Any soap will do.

The American Chemical Society did a great video, Can Soap REALLY Kill the Coronavirus?

It features Professor Palli Thordarson, whose Twitter thread about how we are so certain that soap kills Coronaviruses went viral.

It's well worth 5 minutes, if only to take a trip down memory land about how a HS chemistry teacher's chance remarks led me to take honors chemistry at Berkeley and change my major to chemistry.  Hydrogen bonds got me hooked on chemistry and played a big part in my PhD research.  It's all so great.  I hope you watch it with your kids.

The short answer is that soap is Kryptonite to fatty structures.  Soap, scrubbing and rinsing thoroughly are all you need to do.  Alcohol (if it is strong enough) and oxidizing agents such as bleach, ammonia and hydrogen peroxide will also work.

There are so many chemists on Twitter, sharing what they know and don't know.  It's a little bit hard to parse it all.  On the one hand, one pair of engineering professors say our water supply might not be safe from CV?
Two researchers, Haizhou Liu, an associate professor of chemical and environmental engineering at the University of California, Riverside; and Professor Vincenzo Naddeo, director of the Sanitary Environmental Engineering Division at the University of Salerno, have called for more testing to determine whether water treatment methods are effective in killing SARS-CoV-19 and coronaviruses in general.
On the other hand, another pair of engineering professors, Wigginton and Boehm, tell us our water treatment systems are effective at killing CV and our water supply is safe.

Which is it?

After much reading, and recalling conversations with a friend and chemical engineering professor that does wastewater recycling research, I can tell you all four of them are correct and they actually came to the same conclusion.  Mostly safe, but more research is needed.

If our water system is well maintained (no leaks, no overflows) then our primary and secondary waste water treatment will remove most of the CV in sewage.  It will end up in the biosolids portion, which will be composted at such a high temperatures that it will kill the CV.

The small amount that is in the liquid part, as long as it is undergoes disinfection either with oxidation (chemical sanitization) or ultraviolet light (UV sanitization), should also be safe.  Here's a flow chart (ha ha) of the tertiary and advanced water treatment steps taken at my LA area's plant:

The purple pipe landscaping water sent out to parks and schools is disinfected and should be safe. The industrial water sent to refineries and power plants for cooling is not usually disinfected.  But, it undergoes microfiltration and then reverse osmosis (RO).  Viruses and bacteria are just too big to get through the little holes of the microfilters.  Even the remnants are too big to go through the many layers of the polymer membranes used in reverse osmosis.  If the system is in good working order, the water sent to refineries and power plants and that you see evaporating into the air is safe.

The water that is put into the aquifers through barrier injection wells undergoes microfiltration, RO, aeration, UV disinfection and then gets some minerals (lime) put back in to stabilize it at a neutral pH.  As long as there are no leaks or biofilms, it's perfectly safe.  It's cleaner than the water that is already there.  In fact, it's the purest source of water available to us in Los Angeles.

Biofilms is the problem that Liu and Naddeo alluded to.  They are incredibly tenacious.  If they form in your pipes, they are really hard to remove.  They also form in water recycling plants.  That's one reason why they need to be taken off-line for periodic maintenance.  They can also form in household plumbing.  Most biofilms are harmless (and I hope the one in my toilet is one of the harmless ones.)  Legionaire's disease was able to spread in hotels and on ships through biofilms in shower heads. What we don't know is if CV can incorporate into biofilms.

SARs spread through Amoy Gardens, an older Hong Kong apartment building through a vulnerability in sewage plumbing.
Recent investigations into the March 2003 outbreak of SARS in Hong Kong have concluded that environmental factors played an important role in the transmission of the disease. These studies have focused on a particular outbreak event, the rapid spread of SARS throughout Amoy Gardens, a large, private apartment complex. They have demonstrated that, unlike a typical viral outbreak that is spread through person-to-person contact, the SARS virus in this case was spread primarily through the air. High concentrations of viral aerosols in building plumbing were drawn into apartment bathrooms through floor drains. The initial exposures occurred in these bathrooms. The virus-laden air was then transported by prevailing winds to adjacent buildings at Amoy Gardens, where additional exposures occurred. This article reviews the results of the investigations and provides recommendations for maintenance and other measures that building owners can take to help prevent environmental transmission of SARS and other flulike viruses in their buildings.
Los Angeles' housing stock skews old.  This is the stuff I worry about.  How well designed, built and maintained is all that old plumbing?  How do we come up with the money and will to take inventory and ensure everyone is safe?  This crisis has exposed so many of our society's cracks.

The COVID-19 Waterblog is available for all you water nerds out there. That's how I learned about Professor Krista Wigginton's research in SARs and CV.  Survivability, Partitioning, and Recovery of Enveloped Viruses in Untreated Municipal Wastewater is fascinating reading.

The American Chemical Society has put together a special virtual issue: Overview of Research on the Fate and Behavior of Enveloped Viruses in the Environment.  It combines older, peer-reviewed research with our best educated guesses based on emerging evidence.

So there's stuff we don't know.  And stuff we do know.  Combining those, we have a good idea of how we should protect ourselves.  Fortunately, even though COVID-19 persists and is detectable in raw sewage for many hours, it appears to be less biologically active in water than SARS.  It's more easily spread in human-to-human contact due to asymptomatic people spreading it around.

COVID-19's ability to spread from person to person is scary enough.  But, I'm not worried about the sewage line that runs down the middle of the street.  Our area pays parcel taxes for water systems in addition to the water bill.  That provides a sustaining source of money to maintain and upgrade systems.  In the time that I have lived here, I've seen upgrades/replacements/repairs on stormwater and sewage systems.  In fact, a large chunk of the sewage pipe on my block was dug out and replaced.

I also know that deferred maintenance is the norm in most parts of the country.  Flint is not unusual. Continuous monitoring and maintenance is essential, but it requires a continuous budget.

Since I became the Natural Resources chair for the League of Women Voters of Los Angeles County, I began writing a monthly roundup of local environmental news-both the science and the policy.  Half of the March newsletter (written in February) was about the safety and affordability of water in LA county.  Are you interested in reading about it here on the blog as well?

What kinds of things do you want to read?

Tuesday, April 07, 2020

Hacking the pattern or using what I've got

Sewing face masks is not fun. I'd much rather sew a lace-trimmed top for my daughter than sew face masks for her. (Though I did do both.) I finished this after 2 AM, put it in her bathroom, and then she put it on right after breakfast. I think she likes it. But not enough to take out her headphones and pose where the light is better. ;-)

I searched through my pattern collection for my tried and true (TNT) woven t-shirt pattern, but couldn't find it.  I think I may have paired some of my TNT patterns with fabric, and then packed them all away for the move back to LA.  I'm missing several of my favorite patterns and hope to be reunited with them as I slowly unpack and sew through my fabric collection.

I like the way Calvin Klein patterns fit my slightly squared shoulders.  I started with this Vogue 1873 blouse pattern, and traced it onto medical exam table paper.  I just cut it on the fold at the center front, rather than copy all the placket stuff.  I also traced a simple neckline, knowing that I would trim it down further to fit the lace trim. I hoped to make short sleeves, but the fabric was tight.

This worked out much better than I had expected.

I stitched the lace trim to the front piece along the perimeter, trimmed the neckline to 1/4" beyond the edge and bound the neckline with bias binding made from some washed rayon from my scrap bin.

I marked the rough area where I stitched down the lace trim.

Another picture of the top and daughter in their natural habitat.

I worked with a remnant ($3) and some lace ($1) from the baskets at the front of Fabrix, a San Francisco odd jobber selling pre-consumer waste sewing supplies.  They both washed and cleaned up well, but I was alarmed at how much this oxford cloth shrank.  It's a beefy 100% cotton oxford that shrank ~10% in length to 32-34" long by 44" wide.  I barely got the two body pieces to fit.  I then seamed the scraps to make pieces large enough to cut out the sleeves.

Nice flat felled seams on the inside.  If the seam was more off-center and were black, I might have put the selvage fringe on the outside as a design feature.  Ultimately, I decided to put it on the inside.

This is all I had left of the fabric after cutting and sewing.  100% cotton can be put in the compost bin, so this was truly a zero-waste sewing project.

Saturday, April 04, 2020

Stay away from the beach

Mea culpa. I was upset when I saw this photo that @seaninorbit Tweeted on March 28, 2020. But I was so very wrong. Read on to learn why I changed my mind and now fully support this ban.

As I cyclist, I immediately bristle when people in cars are given more rights than people outside of cars. Read the sign in this photo.

The beach bike path below is closed. The wide sidewalk for pedestrians at street level is closed. The on-street bike path is closed. Pedestrians and bicyclists are banned from the street. The city of Redondo Beach appears to be saying that only people cars can use the street.

By law, our streets are supposed to give access to all modes of travel.

Where are people outside of cars supposed to go?  I felt that this was another auto supremacy move by our city and police department.

Then I read Rosanna Xia's piece about why people should stay away from the beaches right now.
In her research, [UCSD/Scripps Professor Kim] Prather has found that the ocean churns up all kinds of particulate and microscopic pathogens, and every time the ocean sneezes with a big wave or two, it sprays these particles into the air. She believes that this new coronavirus is light enough to float through the air much farther than we think. The six-feet rule, she said, doesn’t apply at the beach, where coastal winds can get quite strong and send viral particles soaring.

“It’s not going to kill you if you miss a few surfing sessions, but it could if you go out there and get in the wrong air,” she said.

“You can’t see the virus, you can’t smell it ... It’s a real silent killer right now.”


“Once things are in the air, they can go pretty darn far. People are shocked whenever I talk about stuff becoming airborne,” she said. “I see pictures of the beach shut down, and the signs tell you don’t walk on the beach, don’t swim, don’t surf, but nobody tells you: Don’t breathe.”
Remember all the other scientists saying how far aerosol droplets can travel before hitting the ground under laboratory conditions? The beach environment is a lot windier and complex than most labs.

You know how you can taste the saltiness in the air at the beach? That clammy feeling on your skin and clothes? That's sea spray.

Salt is corrosive. People who live near the beach know how far sea spray travels because we have to combat the corrosiveness with constant home maintenance.

Salt and sea spray is also hygroscopic--it attracts water. Small droplets can attract moisture out of the air and become bigger droplets that fall more quickly. That stuff can fall on you and stick.

Conversely, sea spray can warm up and evaporate some of their water, becoming lighter and able to travel further. Add stiff sea breezes and you have a complex aerosol environment with who knows what blowing quite a distance inland depending on sun and wind conditions.

Dr Prather also cautioned that stuff that precipitates out of the air can be washed out in the ocean and become re-aerosolized.
Coronaviruses are encased by what she calls a “hydrophobic” lipid, or fatty, membrane. Fat tends to float to the surface of water, similar to oil in a vinaigrette dressing. When waves break in the surf zone and all the foam and bubbles pop, Prather said, “all that stuff — the viruses, the bacteria, pollutants, all the gooey, oily stuff — just launches into the air.”
That surfer that said he was going out when the surf was up, no matter what? He's not just endangering himself.  He could be an asymptomatic virus shedder exhaling into the sea spray.

Alison D. Nugent et al recently found "We've also found a stronger relationship of Sea spray aerosol (SSA) number concentration to wave activity than to wind speed in our coastal measurements."

Even if people are spaced 6 feet apart in the bike lane right along the coast, that's not enough.  Better to bike the inland route right now.

Many regular bike commuters wear N95 masks to protect themselves from car exhaust and PM2.5.  If you don't have that, wear a homemade cloth mask, stay away from cars and other riders as much as you can.